Wednesday, October 1, 2014

Cooling Pump Follow Up

If I had one thing to add to the previous post, one thing I've learned, it's don't send a boy to do a man's job.  Let's recap the story of my attempts at cooling the Zilla controller in the car. 

The first cooling solution I installed in the car was essentially a kit sold by EVSource.  It came with a little 4x8 inch radiator, and a Laing D5 Strong pump.  The car hit the road in March of 2010, when the average daily high temperature is about 75°F.  All was right with the world.  However, by late April, when temperatures are beginning to approach 100°, I noticed the controller starting to over heat, and go into thermal cutback after I'd traveled a couple miles from the house.  It turns out that a radiator from a kit designed for a liquid cooling system for a computer wasn't up to the task of cooling a 1000 Watt controller.  Go figure!

What did I do about that?  I added a couple of 120mm fans to the radiator.  But as the car was off the road that summer while I re-did the battery layout up front, and removed the motor for repairs due to faulty balancing putty, I never got to test this solution in heat of the summer.  When next summer rolled along, I found out that it was only slightly more effective than the previous year when I had no fans. 

Attempt #3 at getting adequate cooling:  I swapped out the little 4"x8" radiator for a nice big 12"x14" that incorporated it's own 10" fan.  I hooked that fan up to a temperature switch on the Zilla so it would spin up if the Zilla got above 122°.  This system was far and away better, but the controller would still go into thermal cutback if I ran it on the freeway for more than 5 miles.  Now, you may notice through all of this, that I never changed out the pump.  The little Laing D5 Strong pump was still in the car spinning away. 

When that pump failed early this summer, I was forced to replace it, and I was fortunate enough to have purchased one of the OEM quality Pierburg water pumps from EVTV.  It would have been far easier to simply swap the bad Laing pump for another, I wouldn't have had to modify anything in the car, but I'm so glad I didn't.

I've run the car in our typical 105° August/September weather, on the freeway for 12 miles at a time, and so far the controller has not complained once about getting too hot.  In fact, I haven't even heard the radiator fan kick on!  If I'm honest, may have come on when I was on the freeway, but I never heard it due to road noise.  The bottom line is that thanks to this Pierburg pump, the controller is finally getting the water supply it needs for proper cooling.  And the properly sized radiator is providing enough cooling area to suck the heat out of that water.  This is a big relief.  Heat is the enemy of electronic components.  The better I can keep them cool, the longer they'll last.

Thursday, September 11, 2014

A Failed Water Pump and Building a Circuit

Sometime in January, I think it was, I was driving the Z3, having a good time, minding my own business, when the  Zilla controller's light started flashing at me, indicating a fault with the controller.  The car kept moving and responding as normal, and shortly afterwards the light stopped.  It's done this in the past, during summer time when cooling system wasn't up to keeping the controller cool.  But this was January, so that couldn't be it.  Right?  This happened a couple more times, completely baffling me.  Each time the fault would clear on its own by the time I got home.  I hooked the laptop up to the controller... No faults.  Hmm.

Shortly after that I took the car off the road for some mechanical upgrades and a few small repairs: new steering rack, and replace the damaged front bumper.  Because I'm careful with my work, and took my time (read lazy), the car was off the road for about 2.5 months.  I got it back on the road in late May.  The first drive back in the car is always glorious.  I love driving the car! 

On that first drive, I was on my way home and the warning light started flasing again.  Then it started flashing faster.  It was at that time I noticed that the car was barely responding to the throttle.  At that point, the light came on in my head and I realized what had been happening all along.  But how could the car be overheating?  A hot day in May, sure I understand, but not to this degree.  And certainly not back in January when it was 60°F outside!  What could possibly be going on?

I popped the hood and immediately notice a small bubble in the line that leads from the Zilla to the radiator.  It pains me to say it, but that is the high point in the system.  Anyway, I notice it's barely moving.  When I'd filled the system, the pump was able to push all that air through the system down to the radiator where I bled it out.  I climbed under the car, touch the little pump and I found it was cool to the touch, and didn't seem to be running.  I tapped it, and it started running, but it didn't sound right.  After much testing and what not, I was able to determine that my little Laing D5 Strong pump had given up the ghost.  That was a big surprise; these things are known to last forever.  Fortunately I had a replacement pump waiting in the wings, but not the same make or model.

Sometime last February, Jack Rickard at EVTV announced that they had some Pierburg water pumps for sale that they'd acquired in the Azure Dynamics bankruptcy.  These are the same pumps used by multiple OEMs including BMW.  They normally retail for nearly $500, and he was selling them for $100.  What a deal!  Maybe it was premonition, but I decided to buy one in case I needed it.  Truthfully, it was probably a stupid purchase at the time, but fate intervened to make me look like a genius. 

The only thing is this pump puts out 8 gallons of water a minutes, but he Zilla only requires 2.  The thing is, more water is not better.  Your first thought might be that more water will likely cool the system better (I know that was mine).  But it turns out that if you push water through a heat transfer system too fast, it simply doesn't have the necessary amount of time when it's in contact with the surfaces to transfer heat efficiently.  Fortunately, this pump has a PWM input signal line that you can use to control the pump, dialing it from 10% duty cycle up to 100%.  The problem is, I know nothing about circuits other than if pressed I can identify a circuit versus say a can of fruit. 

I decided to do a little Googling to see what I could find, and wouldn't you know it, I found a YouTube video (since taken down) posted by a man named Klaus Wolter about how to control the pump.  He subsequently posted a design for a PWM circuit he'd designed to control the pump.  I'm reprinting the circuit here, though I have no way to contact Klaus for permission.  Klaus, post a comment if you object.

For those of you who don't know, a PWM signal, or Pulse Width Modulated signal, is simply a series of On-Off signals used to control a motor.  Now some PWM controllers actually send current to a motor to control it's speed, like for instance the Zilla controller in Z3.  Others simply produce a PWM signal with no current.  That's what this pump requires.  It reads that signal and the circuitry in the motor interprets it and then controls the motor's speed, meaning that this circuit doesn't directly control the motor.  It became clear that I was going to need that circuit if I was going to make this pump work in my car, so I decided to give it a go and try and build it.

I found a couple electronic component stores near by and went and collected all the parts I'd need. I bought at least two of each figuring that I was sure to foul up the first attempt.  Next, a friend encouraged me to buy a bread board so that I could build it out first without soldering any of it.  The only problem is that there were a couple aspects of the circuit that I didn't understand, particularly how that diode fit in.  Fortunately my bother-in-law Mark is an EE and he talked me through it, showing a great deal of patience I might add.  I put the circuit together on the bread board and sat there staring quite proudly at my accomplishment.  It was at that time that I realized I had no way to test it.  I don't own an oscilloscope.  But, I had an idea.  I know that motors controlled by a PWM circuit see an average voltage depending on duty cycle.  If you have a 100 volt system, and you're driving the motor with a 50% duty PWM signal, the motor "sees" 50 volts.  OK, really it sees 100 volts for 50% of the time, but since it's switching on and off so fast it averages out to 50 volts.  I'm sure every EE reading this is going to be shaking his head for some reason, but that's how I understand it.

With that understanding, I thought I might be able to throw my multi meter on the circuit's output and I should be able to measure a difference as I twisted the potentiometer.  Sure enough, I could!  OK, time to solder it up.  Here's what I ended up with.

Not terrible for a first ever attempt.  But would it work?  I hooked it up to the pump, ran some hoses to a bucket of water and turned it on.  Nothing.  I could feel the pump was on, but it felt like it was barely running.  If I twisted the pot I could tell the motor spun a bit faster, but still the pump moved no water.  Well, time to troubleshoot the circuit.  I spent hours going over it, checking and re-checking, but it all looked good.  I finally decided I was going to EVCCON in a week or two, I would take it there and ask some friends there if they could take a look at it. 

I explained the situation to a friend, one of the attendees, Doug Ingraham and he happily offered to help.  We borrowed Jack's oscilloscope, hooked it up, and to my great surprise, the circuit worked perfectly!  I was thrilled, but puzzled as to what could have been the problem when I was testing it.  It took a quick conversation with Jack to discover the problem.  Once again, it was my surprisingly great ability to assume that was my downfall.  I had assumed that if there was a problem, it MUST be the circuit I'd just built.  In my defense, that was more than 99% likely.  In this case however, it was the fact that these pumps are not self priming.  There was no way the pump was ever going to suck water up out of a bucket.  *Hand on forehead, shakes head slowly.*

I got back from EVCCON, and the next day tested the pump with a gravity fed system and it worked perfectly.  But it was a good thing I spoke with a number of people about this while at EVCCON because I learned I was going to need to make a couple other modifications to the car to accommodate the larger diameter inlet and outlet from the pump.  Particularly I was going to need to make sure that the pump had enough water feeding to it, or the pump would cavitate, ultimately ruining the pump.  The old pump had a 3/8" input, but new one, 3/4".  The tiny reservoir that supplied coolant to the old pump, with its 1.5 cup capacity and 3/8" outlet would not do.  I replaced it with a 1 quart model that has a full 3/4" outlet and inlet. 

I had the whole system together a couple days later, and the car was back on the road running cooler and better than ever.  That is until I turned on the A/C for the first time and found that it had lost it's charge.  I think I might have hit a hose or something while working in there, perhaps I broke a seal and allowed the gas to escape.  *Sigh*  It never ends.  But winter is coming.  I don't need to attend to that right away. 

Monday, May 12, 2014

Wheel Alignment

Recently I had to replace the steering rack in the Z3.  This was a completely new experience for me as I've never messed with any car's steering components.  As it turns out, it wasn't that difficult.  As a friend accurately stated, "It's all a mystery until you've done it once, then it's just work."  The plan was that after I got the new rack on, I'd drive it a couple miles to the nearest Costco to get new tires, and then a mile from there to have the front end aligned.

Of course, I needed to try to get the tires as properly aligned as possible for those two short trips between the house and those two places, otherwise I risked scrubbing the remaining rubber off my tires (at best) or losing control and getting into an accident (at worst).  But how?!  I don't have any fancy alignment systems.  Then I came up with a clever plan.  I still have two 5 foot pieces of 1" angle aluminum laying around.  I clamped one to each of the brake disks on the front end, with them sticking out in front of the car.  I pointed the steering wheel straight forward, and then took a measurement of the distance between the brake disks where the angle aluminum was clamped.  I then adjusted the toe-in, toe-out until the measurement between the end of the angle aluminum was the same as it was at the disks.  So how did I do?  I needed to wait for the shop's initial measurement to find out.

I got the new tires on and dropped the car off at the shop.  I told them when they aligned the car, I wanted it set so that the tires had no toe-in.  In other words, I wanted the wheels aligned for 0° toe-in.  After all, this is what I'd had done before, and is generally accepted by EV enthusiasts as a great way of reducing rolling resistance.  Ultimately every degree you have dialed into the toe-in is more energy that gets scrubbed off your forward momentum.  Of course, we've all come to accept the fact that having the car aligned with 0° toe-in means that the car tends to wander a bit when you head down the road.  You get used to the car sort of following the grooves in the road, requiring you to work the steering wheel a little more to keep the car in a straight line.  Not a big hassle by any means, but certainly not what most people are used to when driving a car.

When I made this request, the owner of the shop stopped and said "Why would you want that?"  I explained that I wanted 0° toe-in for efficiency reasons.  He considered what I said and replied "That won't get you what you want."  "Why?" I asked.  He explained that as any road car moves forward, there is a certain amount of force pushing all the tires back.  OK, that makes sense.  He went on to explain that this force will inevitably cause a certain amount of deflection, or flex in the rubber bushings that make up the steering/suspension, causing the tires to lose some of the toe-in that's dialed in when they are aligned.  He stated that if I started at 0°, once the car was moving forward, and the tires were experiencing that road resistance, that pushes them back ever so slightly, I would end up with a slight bit of toe-out.  He continued saying that in such a case, you'd likely find the car wanting to wander a bit as you went down the road.  That got my attention.

Sensing that this could be very important I replied, "Go on."  He said "We normally dial in a total of 16, or 8 for each wheel.  I would suggest that we halve that to 4, or perhaps 3 on each wheel.  That way, when you're going down the road, you're more likely to be at 0° or just a bit less.  That should get you the efficiency you want, and the car will track truer."   I asked him exactly what measurement 16 was.  What was the increment used?  Is it degrees, tenths of a degree, furlongs, what?  It turns out that it was 1/100ths of a degree.  That means that normal toe-in would be set at .08° for each wheel, and he was proposing .03°.   I told him to do it, .03° it is!

The fact that the increment used for aligning the car was 1/100th of a degree seemed to me to make his claims that much more plausible.  The reason I say that is because if the standard increment used for aligning the car had been higher, say like 1/10th of a degree, he would have been asserting that the deflection in the steering geometry was in excess of .6°, which seems a bit extreme to me.  But with the measurement's increment being 1/100th of a degree, the total deflection in the steering geometry is more like .06°.  A more plausible prospect. I have no way of knowing if what he says is true, but it certainly sounded reasonable.

So the ultimate question is was he right?  To know the answer to that, I'd have to be able to see either no loss of efficiency in the car, or even better, a slight gain in efficiency.  Plus I should see the handling improve as the car should track down the road better.

Unfortunately I'm unable to say with any certainty whether the car is more or less efficient in rolling now.  The only measurement I have at my disposal to determine this is the average watt hours/mile.  As most of you know I've been collecting that data with every trip the car makes since it hit the road.  Doing so was what helped me discover that the Helwig Split H60 brushes were more efficient than the standard H-49 brushes that came on the Netgain motors.  But the value, or worth of that number is dependent on all other things in the car remaining the same.  If you change two things at once, there is no way to tell what's responsible for the change in readings.  Well having just put a brand new set of tires on the car, I've completely negated the relevancy of any efficiency numbers I've gathered since those changes.  That said, the car is using a bit more energy per mile.  It had been averaging 320 Watt hours/mile, but it looks like we're up to about 350.  Is it the tires?  Is it the alignment?  Impossible to say.

What I can say is that the car drives great.  It tracks down the road beautifully and is better to drive than ever.  In that regard, the service shop owner seems to have been correct.  I'm calling that a win.

Truth be told, I'm much less interested in the minor increase in efficiency that might be on the table, than in gaining what most people would refer to as "normal" driving car.  Not unlike when I abandoned the nifty little proximity cut off switch I'd designed for the power steering pump.  It worked just fine, and saved a bit of energy, but you had to turn the steering wheel a couple inches before the power steering kicked in, which meant for those first few inches there was no power steering.  It wasn't all that difficult, but it was strange, and I had to explain it to anyone that drove the car.  I don't want a car that drives oddly, and neither does anyone else for that matter!  But for me it's probably for a slightly different reason.  I don't want anyone who allow to drive the car saying "It's great, except for this one strange thing..."  I don't want anyone's first EV experience tarnished by having to work the steering wheel like a saw as the car meanders around the road.

The point is, if you're having your car aligned with 0° toe-in, thinking that it's remaining that way when you're moving down the road, and you're enjoying a lower rolling resistance, you might be wrong.  Your car might be rolling down the road with a slight toe-out.  What would be great is if someone else with a 0° toe-in set on their car could gather a lot of efficiency data, and then have their car re-aligned to .03 or .04° toe-in per wheel and then report back.  Any takers!?

Oh, and incidentally, the alignment I did in the garage was .63°.  Not bad for a guy with a couple of sticks and a measuring tape.

Wednesday, November 13, 2013

Brakes, Car Shows and Solar Power

One of the readers of the blog emailed me a week ago and asked me if I was going to be updating the blog anytime soon.  He was wondering how things were going with the Z3 and if there was any new, interesting things to report.  There are a couple of small things that I thought I'd share, but really, there hasn't been much to report, so I haven't posted anything.  But then it occurred to me that not having much to report is itself, worth reporting.

Anyone who has read through this blog is keenly aware of the various issues and problems I've had with the car.  Usually brought on by a hardware/component issue of some sort, and occasionally brought on by my own ignorance or stupidity, I've tried to turn these episodes into some sort of learning experience, or at the very least, a good read.  These events have occurred frequently enough that I think people have become accustomed to regular posts.  But as luck would have it, nearly a year has passed with no serious issues or problems with the car.  I drive it, plug it in, charge it, and then drive it some more.  Not a particularly entertaining thing to read about on a daily basis.  But the fact that this has been going on for the last year, with no drama, is pretty damned cool.

Truth be told, it hasn't been completely trouble free; I have suffered a minor hiccup.  Sometime mid-summer, the MES-DEA vacuum pump I use for my brake booster stopped working.  It was a bit surprising, and a tad scary as I suddenly needed near Herculean strength to stop the car.  My overall impression at the time was "This is bad!"  I decided I should probably replace it. Apparently the MES-DEA pumps use a diaphragm which over time wears out and tears. As it happens, right around the same time that mine broke, EVTV started stocking a new, double piston vacuum pump.  The problem with the piston pumps is that they are notoriously loud.  But Jack demonstrated this on the show and I was pleasantly surprised at how quiet it was, so I decided I'd give it a go.  The only problem, it's a little bigger than the existing one, which means I'm going to have to do some re-design work to fit it in the car.  *Sigh*  I just haven't been able to muster the will to do it yet.  In the meantime, I've been driving the car carefully and found that the brake pedal has gotten easier every week.  A by-product I didn't expect is that my right leg has gotten much stronger and my pants don't seem to fit the same from one leg to the other.  I'm going to end up looking like Mr. Atlas on my right side.

Perhaps the biggest news, which isn't directly related to the car is that we had a 6.1 kW photo-voltaic solar array put on our house.  We contracted to do it through Solar City which has worked out tremendously well.  For a lease price of $70/month, it is off setting an average of $110 of electricity cost per month.  I call that a win in every respect.  When it comes down to it, it's producing roughly 1/2 to 2/5ths of the power we use.  In September it produced 963 kWhs, and in October 775 kWhs.  As Winter comes and the sun is lower in the sky and up for less time, that number will continue to drop.  But our consumption drops accordingly due to the fact that it's no longer 115 °F all the time.  Lately, I've taken to charging the car in the middle of the day.  So while I'm not powering the car exclusively on sunshine, it's very satisfying to know that a good portion of the electricity pushing the car was from the solar array.

As many of you are probably aware, Plug In America day occurred on Saturday last September 28th.  Every year the Phoenix chapter of the EVAA plans a gathering of electric cars for this event at a weekly car show that takes place here in Phoenix.  Usually I can't join their events scheduled for Saturdays, but in this instance my schedule cleared up and I decided to take the Z3 down to the show.  Now, to give you some perspective, I brought my car down to the same event two years ago.  There was a grand total of 8 EVs: 3 Leafs, a Smart EV, and 4 conversions.  This year was a bit different.

I showed up about an hour after the event was supposed to start.  I found the EV group and was shocked to see 50+ cars on display.  There were 25 or so Leafs, about 5 Volts, a few Ford Focus EVs, 3 Tesla Roadsters, 1 newer RAV4 EV, 8 or so conversions, and about 10 Tesla Model S's.  I was shocked.  I talked to Sam, one of the club's leaders and he welcomed me and told me to bring my car around to join the group.  Looking around I saw no parking spaces left but he said "Don't worry, we'll find a spot for you."  I walked away to go get the car and when I returned, it just so happened that one of the Model S's had pulled away in my absence, so Sam had me take that space.

So there I was, a little home built EV with 4 Tesla Model S's on either side of me.  It was an odd situation, kind of like seeing the cute high school girl you knew from your youth, surrounded by a bunch of super models.  Suddenly the little Z3 wasn't quite as impressive as she once had been.  But then a curious thing happened.  A crowd began to gather around the car.  Everyone started firing off questions.  "What kind of motor did you use?"  "How long did it take you to build it?"  "How many miles have you put on it?"  Suddenly, the super models next to me were largely being ignored, and people were mostly gathered around my car.  But then I realized that they weren't only around MY conversion, every one of the conversions had a crowd around it, were as very few of the manufactured EV's did.  It's easy to understand why that is.  Pretty as they are, once you've seen one Model S, you've pretty much seen them all.  Plus, there's no way to see the guts of the car, whereas the guts of my conversion, and indeed most any other conversion, are out on display in all their glory or horror (depending on your perspective and the car you're looking at).

Maybe I'm pushing it, but I see this as an indication that conversions are not likely to go the way of the dinosaur simply because you can buy an OEM EV.  Just like custom built hot rods haven't gone away even though you can go out and buy a really great muscle car for a fraction of the cost.  Nope, the appeal of custom cars, be it hot rods, or EVs will be with us as long as we use cars.  I spoke with one Tesla Model S owner that also has a Porsche 914 conversion in his garage.  After he got his Model S, he was bothered by the fact that it was faster than the 914.  So, the 914 was put back in the garage so he can upgrade it and fiddle with it until it's once again the fastest car he owns.

But, I digress.  The point of this story was just to illustrate that adoption of EVs really is starting to get some traction.  From 8 cars 2 years ago, and the few people who wondered by looking at them with idle curiosity, to 50 plus cars and dozens of people engaged and asking questions.  Things have changed quite a bit.

Finally, an entertaining story.  A month or so ago, my lovely wife and I were heading out for a shopping errand.  As the circumstances of our lives happen to be, she doesn't ride in the car very often, so it's kind of a treat for her.  Well OK, I define it as a treat, but I'm not entirely sure that she does.  At any rate, I stopped at a sign and for whatever reason, she looked over at the dashboard.  Apparently, she caught sight of the fuel gauge, which is still in the instrument cluster, and she said, with a certain amount of panic in her voice, and in all earnestness, "Oh my God, you're completely out of gas!"  I slowly turned to look at her and I saw the look of alarm on her face change suddenly to one of realization and then embarrassment.  I was doing my best to suppress the laughter as she was shouting various excuses "I just forgot!  I haven't been in the car for a while!  It was just habit!"  I just smiled and nodded, and we zoomed away in silence.

Monday, May 20, 2013

A Long Overdue Upgrade

From the moment the Z3 hit the ground after I finished the conversion I knew that I was going to have to upgrade the suspension. The car's front springs were already tired, and before I added 485 lbs worth of batteries and equipment, the car was already riding 3/4 of an inch lower than stock.  After it gained all that weight, it was riding an additional 3/4" too low.  So now, both the front and the back were 1.5" too low.

I tried to reduce that 1.5" drop by adding some rubber bushings in between the lower coils of the springs.  That brought the ride height up by 3/4".  It was still a bit low, but the car looked good.  The problem was that the trouble was deeper than just ride height. The springs were never meant to carry the additional weight I'd added to the car.  When I went over a speed bump at just the right speed, the front end of the car would dip too much as I was coming down, and the car would bottom out.  The springs were simply too squishy.

So, knowing all of this, why did it take me so long to finally address this problem?  When people asked, I'd blame it on the cost of the components: all the suspension components add up to $1,500 or so.  But truthfully, it was fear.  I've never worked on any aspect of suspension systems before and as far as I was concerned the car's suspension is made up of springs, swing arms and shock absorbers all held together with  black magic and voodoo.  It seems silly really, after all, I did take a perfectly good car apart and turn it into an EV.  What could be so difficult about suspension?  Clearly this was not a rational fear.

Doing research into the subject, I came across a recommendation for a company called TC Kline Racing that specializes in BMW and Porsche suspension systems.  I contacted them and told them what I'd done, explaining that my goal was to get the car back to a normal ride height with properly rated springs.  I'd kind of anticipated this before I'd started the conversion, so I'd had each corner weighed both before and after the conversion.  That allowed me to tell them exactly how much weight each corner gained.  They informed me that the original springs were 325# rated springs, and I would need to upgrade to their 400# springs.  Those heavier springs would get me the ride height I wanted and the suspension would have the proper firmness.  The end result would be the ride should have the right feel and handle better.

The full kit included the 400# springs for both the front and back, Koni coil over struts for the front, shocks for the back and a threaded barrel and collar system that would allow me to adjust the ride height on the back of the car.  One of the claims they made was that the system weighed less than stock, which would reduce the car's unsprung weight and further improve handling.  So when everything arrived, I weighed it and it came in at 41 lbs.

My dad agreed to come over and help me with the project, which I had hoped would take only a day to complete.  <shakes head> Oh... silly boy.  I'll spare you the brutal details, but it took us about 2 hours to get the first strut done.  Getting it off the car wasn't too bad, but we needed to compress the spring so that we could get the top plate off since it needed to be re-used.  That top plate is what holds the strut assembly to the tower.  Compressing the spring was scary.  We had the right tool, but we felt like we were working with a live hand grenade that could go off at any minute.

The second strut went a bit quicker, and after 3.5 hours of work we had both new struts on the car with everything torqued down to spec.  We weren't going to set the car on the ground until I had the back end complete, so I didn't know whether the ride height had been improved or not.  So we moved our attention to the back end.

Getting the old springs off was equally as terrifying, but we got it done and took the old shocks off.  When I went to put them on, it was clear that the larger central shaft of the new shock would not fit through the stock bushing/mount.  A quick call to TC Kline and he said "You needed to order the proper new ones as the old stock ones won't fit."  You don't say!  Since I'd ordered exactly the parts they'd told me to he took responsibility for leaving them out of the package and had them rush shipped to me.  That meant a two day hiatus waiting for the parts.

When the parts arrived, I got the new shocks on the car and the new springs.  I set the car on the ground drove it down the street and back so that it would settle to it's final ride height.  I had to make a few adjustments in the back to get the right height, but the barrel/collar system made it easy to do.  I ended up setting the front struts so as to push the car up as high as the adjustment would go, and it was still 1/2" lower than stock.  I was a bit concerned, thinking that Kline's recommendations had been off.  But thinking back, the real problem was not the ride height, it was the fact that the springs were too soft.  So I decided to take the car out for a spin and put them to the test.

I was astounded at how perfect the car handled.  The car handled speed bumps perfectly, no bottoming out, and if felt like I'd remembered it did when I first bought the car.  Actually no, it felt better.  I really put it through it's paces taking a few corners near the house at speed and found that it handled better than it ever had.  There's a particular corner nearby that has a nasty bump right at the apex.  Previously when I hit that, the front would squirm a bit and the back end would kick out resulting in a relatively unpleasant feeling.  But this time through, the car took the bump like it was nothing at all.  I was so surprised an after market system could be that much better than the stock BMW suspension.  But to be fair, the stock system was 13 years old and had 149,000 miles on it.

I weighed all the parts that came off the car and they totaled 50 lbs.  A savings of 9 lbs, some of which is considered unsprung weight.  TC explained to me that a spring's weight is considered half sprung and half unsprung.  Makes sense.  Incidentally, I spoke with TC personally on the phone 2 or 3 times.  He was very personable and helpful and he took the time to educate me.

I guess the lesson learned here is that if you're converting a car, don't wait to have the suspension addressed to handle the new weight.  If I'm fortunate enough to convert another car, I'll be incorporating that cost into the initial build cost estimates.

When it was all said and done, the car rides 1/2" lower than stock, and looks great.  But more importantly, the springs are rated correctly for the new weight of the car.  Why did I wait so long?

Monday, March 18, 2013

Three Years On the Road

It was three years ago that the Z3 rolled out of the garage as a fully operational electric car.  It seems like an appropriate time to run through some statistics, as well as some of the hi-lights and some of the low points that the car and I have experienced in the last 1096 days (there was a leap year in there).

Number of miles driven: 14032
Number of charge cycles:         742
Average depth of discharge: 34.6%
Greatest depth of discharge*: 93%
Total kWh's used:                    4948
Total cost of charging the car at $0.075/kWh: $371.10
Total $ saved on not buying gas: $2001.62

Some of you may have noticed the new widget toward the bottom of the right hand column.  You may have even noticed that my numbers don't seem to match it.  I recently enrolled the car in the EVClub website, which is a nifty site whose intention is to track how many electric miles have been driven by it's members.  They also provide this nifty widget you can place on your website to keep everyone up to date on your EV miles.  Well when you enter the data for your car the first time, it asks for the number of electric miles you've driven so far and the price of gas.  I entered the current price, but really what it needed was the average price.  Thus the discrepancy.  I assure you, the total above is correct, but the one in the widget is close enough for government work.

The saga begins...

Two months after it's launch I noticed a vibration in the drive line   After disassembling the drive line  I was able to isolate it to the motor and discovered that the balancing putty had fallen off the armature.  After the manufacturers finish winding the armature, there is bound to be a slight imbalance in it.  To correct this, and save the motor's bearings, they bake some putty on one side to even things up.  Well mine fell off.  Netgain had it shipped back and repaired all at their expense.

By the time the car was back on the road, it was mid summer, and I realized that I've grown soft in my middle aged years.  A car with no AC was fine when I was 16 or 19.  Not when I was 45.  It sucked.  But I wasn't the only one suffering.  The Zilla controller was flashing warning lights at me, constantly warning me that it was in thermal cut back mode, dropping me down to 50% power.  Clearly I was going to have to get some cooling for me and the controller.  I couldn't address it then, and frankly stopped driving the car for the remainder of the summer.  A trip here or there at night, but that was it.

That following September, I blew up my charger.  A completely self inflicted wound, but this blog is all about honesty.  While charging the car, I was measuring one of the batteries.  The probe slipped and managed to touch part of the chassis and the battery terminal at the same time.  The Manzanita charger is not an isolated charger, meaning that it is grounded to the chassis.  Why, I have no idea.  But the consequence of this is if you do what I did, your charger blows up.  Fortunately, or unfortunately depending how you look at it, this is not an uncommon problem for people with Manzanita chargers, and Manzanita Micro has gotten rather good at fixing them with a quick turn-around time, and for a very reasonable cost.

The sharp minded among you will be saying to yourselves "Clearly he had something, probably a mounting bracket, too close to the terminal.  What a poor design.  What an idiot!!"  And you'd be right.  To address this, I could either spend a lot of time, effort and money to redesign the battery rack.  That, of course, would be the right thing to do.  OR, I could simply wrap all of those metal bits in rubber.  Which is what I did.  Only one degree up from "idiot" status, but it was a step in the right direction.

Nine months after the motor went back in, I notice the drive line wobbling again.  You guessed it, the putty fell off.  Again!  Netgain to the rescue one more time.

This time, since the car was apart, I decided I was going to fix the cooling issues.  I added a Masterflux AC system to the car, and a much larger radiator for the Zilla.  But as the car went back on the road in early September after that work, I didn't get the opportunity to really put the new cooling systems to the test.  That would have to wait for summer 2012.

Five months later (January 2012) I turn the charger on and hear a pop at the front of the car and the charger turns itself off.  To make a long story short, the car had a frame leak, meaning that you could measure the high voltage system on the chassis.  That is bad.  I was shocked and sickened to discover that the motor was once again the problem.  A build up of carbon dust from the degradation of the brushes resulted in a frame leak that I could not clear no matter how much air I pushed through the motor.  Plus, I found one of the brushes had been drilled by Warfield (the people that build the motor) and it had started to crumble. Who knows where that crumbling carbon went and lodged itself!  Netgain to the rescue once again.  George decided he'd had enough of this motor and sent me a brand new one.  I still can't sing his praises enough.  But I'm certain he curses when ever he hears my name.  George told me that he has my old motor in his garage and plans to put it in a Bricklin that he's been planning to build.  I really hope it treats him better than it did me.

The summer of 2012 came and went and the cooling systems I'd installed the previous year worked great.  I was cool, the Zilla was cool, we were both happy.

In July however, while checking to see if the batteries were still balanced at the bottom of the state of charge, I blew up my e-Xpert Pro meter.  Another self inflicted wound.  I didn't just blow it up, once I pulled it out of the dash, I realized it nearly caught fire.  For the price of one brand new meter, the car was whole again.

September rolled along, I went to charge the car one morning and the charger emitted a series of loud pops, a couple bright flashes, and then some smoke.  The charger made another trip back to the repair shop.  Talking to Rich Rudman, the owner of Manzanita Micro, he said he believed it was due to a faulty set of mosfets they had received some time back.  I got the charger back only to find that it wouldn't charge the car consistently.  The current output would jump all over the place.  So another trip back to Manzanita.

The last post I put up, from January, detailed a problem with more carbon build up in the motor.  That was easily resolved by re-positioning the inlet for the motors cooling fan, and with the aid of a leaf blower hooked up the cooling duct.  It blew every bit of carbon out of that motor.

There you have it.  Three years worth of EV adventures summed up in a few paragraphs.  I guess I focused primarily on the bad stuff.  But the fact is that the good stuff wasn't one or two events.  It was all the times between those problems.  Really, it's any time I get to drive the car.  I simply love it.  The 14,000+ miles of driving bliss far and away, out weigh the troubles I've had.

I've kept close track of the costs associated with building the car, and I can tell you that it cost me as much, if not a bit more than a new Nissan Leaf would have cost me.  Of course the Leaf wasn't available when I started building the car.  Nissan hadn't even announced it.  So would I swap the Z3 for a Leaf or another OEM electric car.  I have to say, there is something very appealing to off-loading maintenance and repairs to a warranty claim.  But missing the satisfaction of having built my own is too steep a price to pay.  Truth be told, I want one of each.  But that will have to wait.

Last week, I ordered some long over due parts for the car.  I'm going to be upgrading the suspension.  I will be able to bring the ride height back up to BMW's spec, and put on some slightly heavier springs to handle the extra 385 lbs the car gained.  Should be fun.

*That excludes the two times I took the cells down to 0% state of charge.  Once to bottom balance, and the second time to check if the cells were still balanced at the bottom after a year's use.  They were.

Wednesday, January 30, 2013

13,000 EV Miles

No doubt the 2 or 3 people that read this blog have long lost interest since I haven't posted anything for 3 1/2 months.  But as they say, no news is good news, and I would say that by and large, that applies here.  I pulled into the garage yesterday after running a quick errand (a Frosty for a sick child), and I took note of the odometer reading.  I delivered the Frosty and then entered the data in my spreadsheet and was surprised to see that the running total of EV miles I've driven added up to exactly 13,000.  Now the 3 year anniversary of the car hitting the road is in a month and 1/2 or so, but this seemed noteworthy enough that I thought I'd post an update of how things are going and include some numbers for those who enjoy statistics.

Keen readers will remember the episode I went through, just about a year ago, with a high voltage leak to the chassis, which I traced back to a frame leak through the motor and ultimately resulted in getting a new motor from Netgain.  George Hamstra was simply sick of repairing it and sending it back to me.  On a side note, George told me he has that motor in his garage and intends to put it in his Bricklin conversion.  I hope it does well for him.  At any rate, in addition to putting the new motor in, George also sent me some new brushes to try out, ones he felt would produce less carbon dust and so were better suited for my application.  He sent me (at his expense mind you) some Helwig Red Top brushes that are made of a harder compound than the standard brushes the Netgain motors come with.

You have to understand, Netgain Motors was born out of the EV drag racing community.  The earlier drag racers kept burning up their GE motors.  George and others saw different opportunities to improve the motors here and there.  They were working with Warfield Electric on building motors that incorporated their changes.  Before long they had a completely new beast on their hands and decided to start selling them.  The brushes they chose were of a softer carbon compound, ideal for pushing high current to the armature   Under drag racing conditions, the motor would generally fail for some other reason long before the brushes did.  But under low current applications, like driving to the store for milk and such, the brushes tended to wear out much faster and give off a lot of carbon dust.  The Helwig brushes have worked out so well for them that they've made them available on new motors.

Understanding that, we get back to my car and the unexpected change I noticed after I installed the new motor with the new Helwig brushes.  Suddenly, the car was more efficient.  About 14% more efficient to be precise.  Jack Rickard of EVTV ran experiments with an old WarP 9 motor he had at his shop, and found the same improvement.  Well, a great deal of time has passed, and I've put many more miles on the car, 4797 to be precise.  I thought I'd take a look at the numbers to see if the increase in efficiency has held true.  The thing is, I realized that I'd been doing the math wrong.  Well, the truth is, I knew I was doing it wrong, but I was too lazy to fix it, thinking the difference would be minimal.  To sum up, I was taking all the trips I made, and averaging the Watt hours per mile used.  The trouble is, the 275 Watt hours per mile used on a 35 mile trip was being averaged equally with the 378 Watt hours per mile on a 4 mile trip.  Anyone can see, those numbers needed to be weighted differently since the distance was different.  The solution is easy: add up all the miles driven and divide it by the sum of kilowatt/hours used.

What did we get?  As I mentioned, I've driven 4797 miles since the brush replacement, and I've used a total of 1526.46 Kilowatt/hours.  That works out to 318 Watt hours per mile.  In comparison, I grabbed a 4804 mile sample of data from before the brush swap and noted that I'd used 1779.72 Kilowatt/hours, which works out to 370 Watt hours per mile.  So does the 14% efficiency gain still hold water?  370 - 14%(51.8) = 318.2.  Apparently so.  I knew the way I was calculating the data before wasn't going to be wildly inaccurate, or even mildly for that matter.  But it's encouraging to see that numbers still hold to be true.

Moving on.  A couple weeks ago I plugged the car in, turned on the charger and heard a familiar "pop" come from the front of the car.  I recognized it immediately as the same "pop" I'd heard before when the motor had become caked with carbon dust and there was a mini flash over in the motor.  What the...?!!!  The only way this would happen was if the carbon dust given off by the brushes wasn't being blown out.  Since the Manzanita charger is grounded to the chassis, when you turn on the charger, if it senses a path from the chassis to the battery pack, it will either throw the circuit breaker in the charger itself, or blow up.  I've had it do both.  For the gory details of each, feel free to look further back in the blog.  Suffice it to say, you don't want to accidentally touch a battery terminal and the chassis with a multi-meter probe at the same time when you're charging.  Anyway, clearly I had a build up of carbon again!  How could this happen?  I've got a fan forcing air into the motor for chrissake! It should be blowing all that dust out.

I checked the fan, and it was running, but the output was very low.  I looked at the filter and found that it was caked with dirt.  Ahhhh.  I'd cleaned it about 6 months earlier, but clearly there's a problem.  Well the problem is really quite simple.  Having no way to locate the fan and the filter higher up in the motor compartment, I mounted it on a tray right next to the motor.  Meaning that the fan and the filter are about 9" off the ground, right were the dirtiest air is.  You may have noticed that every manufacturer locates the air intake for their cars as high up in the engine compartment as possible.  I'm thinking that may be intentional.  I took the filter off and the flow of air was much better, like I expected it to be.

So now I'm left with two problems.  First, the motor is full of dust and I need to blow it out. Second, I need to figure out what to do about this filter location; clearly where it's at is not the best place for it.  Last time I had a dust problem with the motor, I used compressed air to blow it out.  That worked pretty well as a huge plume of dust came out when I aimed the air gun into it.  The problem is, I have to take the motor's shroud off, and to do that I have to take out the batteries over the motor and to do that I have to ...  you get the picture.  Curse the idiot that designed this!!!  But then I had a flash of inspiration.  What If I simply hook up my leaf blower to the inlet hose, the one that runs from the fan to the motor.  Leaf blowers put out a crazy amount of air.  Oh, now this will be good.  Or at least fun.

It wasn't easy, but I was able to get to the inlet hose and basically taped the end of my leaf blower to it using my favorite tape in the world, gaffer's tape.  It's basically black duct tape, but easier to tear.  I had my daughter sit in the car and rev the motor up to about 3500 RPM, and I turned the blower on.  I was very pleased to see a plume of black dust come out the back of the motor (and also a bit disturbed).  I let it run this way for three or four minutes until I was confident it had expelled all the free carbon it could.  The great thing was, I could put my hand at the back of the motor and feel a tremendous volume of air coming out.  I started to wonder, could I some how use this leaf blower as my motor fan?  Apart from it being impractical, it would make the Z3 the noisiest EV on the road, ever.  No, what I really need to do is sort out the filter location problem.

With the fan located low like it was, it's collecting dust at a much faster rate, and ultimately choking the motor.  I looked, thought, measured, looked, thought some more and came up with nothing.  There is simply nowhere else to locate that filter.  Then I had a thought.  what if I eliminated the filter completely?  Stick with me for a moment.  The Netgain motors come with a screen covering the front bell housing, and the brushes.  People run them like this all the time.  The problem is some dirt and sand will inevitably get in and get on the armature and brushes cause them to wear prematurely.  OK, so that's the trade off.  But now, what if the inlet for that air came from a place that was less prone to see dirt and sand in the first place?  After all, the front of the motor sits right where you would expect most of the dust and grime to be, so if I could find a place for the inlet that would provide cleaner air than that, I should be good.  What I found was that there was a way to run a 3" hose from the fan inlet up in front of the firewall and just behind the large battery pack that's over the motor.  It's shielded from the main airflow when the car is moving down the road, yet it's got an open area large enough that it can easily get all the air it needs.  I checked and the output of the fan was terrific.  As far as I'm concerned, problem solved.  It's true that a bit of dirt may be blown into the motor, but I think this is a far better solution than cleaning the filter weekly to ensure good airflow through the motor.

The truth is, I'd love to get a fan that would push more air into the motor.  The one I have pushes 120 CFM.  George even said that's likely too low.  The problem again is one of space.  The fans I've found that push more air won't fit in the space I have.  I keep an open eye out for one, from time to time I comb through the interwebs looking for a suitable candidate.  So far, no luck.

That's all for now, but check back in early March on the car's 3rd anniversary as I'll post some more stats.