Thursday, March 11, 2010

More Data

So far, I've put nearly 300 miles on the car. Everything has been working, more or less, perfectly. So lets have a look at the data.

I'm averaging about 330 Watt/Hours per mile. I've seen averages as high as 394 and as low as 288. That's leaving me a 50 mile range. What I can tell you from this is that the manner in which I drive makes a big difference. But there's a bit more too that story.

The meter shows that the car is drawing 0.2 amps when it's off. That seems pretty reasonable, after all the Zilla draws a small amount of current, as does the Link 10 meter, and the DC to DC converters are always pushing 13.2 volts to the 12 volt system. However, I've no idea if something on the original 12 side is leeching power from that. What I have found though is that if the car sits for 12 hours unattended, it will draw off something like 500 Watt/hours. Hmmm.... I need to find out what's happening there. So the higher numbers I'm seeing in the Watts/mile adventure above are a bit skewed because some of those have a power vampire worked in.

No improvement on the acceleration issue, but I do have some more information. I've noticed that under full acceleration the meter shows I'm drawing no more than 200 amps from the batteries. Well, that certainly lines up with what I'm seeing. 200 amps fed to a WarP 11 motor will produce about 40 ft/lbs of torque. The question is, why not the full 500 I've set? Again, I'm left with one of three things. The Zilla simply isn't drawing the higher current because of a fault in manufacturing or an incorrect setting. I don't think that's it. The hepa pedal isn't sending the proper signal to the Zilla, or the Zilla isn't interpreting that signal as a 100% "throttle on" signal. That seems just as unlikely. Last, the batteries can't release that kind of current. According to the manufacturer's spec, they should be able to release 480 amps for 20 seconds straight. And event higher discharge current for even shorter periods of time.

That leaves me sort of scratching my head. I need to test each independently. I've reached out to the various distributors that I worked with for assistance, so I'll keep you posted there.

I had the car weighed yesterday. I found that through all this, the car has gained a total of ... drum roll please.... 386 lbs. That's about 136 lbs more than I'd thought, but really not bad. So, the car weighs in at 3,285 lbs. The ride height at the back hasn't changed, but on the front of the car it's 1/2 inch lower than stock. Considering that new spring kits for the car, designed to lower the ride height will take 1 inch of the height, I don't think I'm going to worry too much about it. Still just to be safe, I intend to ask a few mechanics. The really cool thing is that I've managed to maintain the same weight distribution, front to back, that BMW had. I've got 52% front and 48% back. Not bad.

Here's a great story. I wanted to have the car reclassified as an EV because the registration fees are a fraction of a regular car. I called the ADOT, our DMV. When it was all said and done, I spoke with 5 people and got 5 different answers as to how I should do it. The one reliable one, as it turns out, was from the fellas down at the only state owned emissions testing place. He told me that ANY emissions testing place can certify it, but often won't because they don't know how. "Which is silly," he said "because all you have to do is look and see there's no engine or gas thank. Done!" He said if they wouldn't do it, I'd have to bring it to him which is about 15 miles away. No worries.

I went to the testing station 2 miles from my house and asked the guys there. They were completely dumbfounded. Completely! One guy said, "Well, we just check that the gas cap fits and plug the car into the computer." So I asked him "And when you find there's no gas cap or gas tank... And when you find the ECU says there's no engine?" Again, blank stares. I said "Look, you're supposed to have a form that you can certify and hand to me that says the car has no engine, and instead has a bunch of batteries." Blank stares.

So, when I pulled into the testing station 15 miles away, and told them what I needed, the guy laughed and said "They wouldn't do it huh?" He was the same guy I spoke to on the phone. He told me this wasn't the first time he's seen this by any means, or the most ridiculous case either. One of the stations in the west valley sent a Tesla owner down to their station to have it certified as an EV. "For-christ-sake!" he said, "That thing was manufactured as an EV. What's wrong with these guys!?" I'm sure I don't know. But I think it will all change soon with all the EVs that are supposed to hit the market soon.


htfiles said...

I think it's a safe bet to say that your controller is not pulling the current it should be (for whatever reason). According to these tests:
Your pack should sag to around 144v when delivering 360A if the resting voltage is 153.6-158.4v (3.2-3.3v per cell). Your pack should be around this resting voltage after fully charging and then driving around for short while (to burn off the surface charge).

The current reading on your Link10 is probably correct or close too it. 200A at 150v gives only 30kW of electrical power. At low RPM (accelerating from a stop) the motor may be quite inefficient. If it dumps half that power as heat, you only have 15kW to the road.

If that's the case, you'll find you've got a stunning 30-40 second 0-60 mph time :-)

I'd see if you can get another throttle to try and look at controller settings.

Tim Catellier said...

Your estimates on acceleration are right on the money.

I had not seen those tests done by EV Works. Very informative and helpful. I'd say you're conclusions are correct. It's either the throttle pedal or the controller. These are the same things I was thinking early on, but wasn't sure how to test them. Still it's nice to have someone else come to the same conclusions independently. Today's post will add some more light.

Thanks again for your help!