The heat here in Phoenix is letting up a bit. Not enough to comfortably drive the car in the middle of the day, but early and mid-mornings have been very nice. Every morning I take the car out for a daily errand, and it's just fabulous. What a great car to drive!
Back before I had to remove the motor, I was giving a friend a ride around the neighborhood to show him the car. I drove by a neighbor that lives around the corner, he and his daughter were in the street playing catch. As we approached, I was worried they might not know we were coming, but they saw us and moved aside and we all waved as we went by.
When we came back by, I slowed down to be sure we were all safe, and the father called out "Is that an electric car?" I told him it was, and he said that he knew it had to be because it hadn't made any noise when we first drove by. I stopped for a few minutes to chat. He had a lot of questions about the car, and seemed truly interested. I answered them all as best I could and waved goodbye.
Over the past few days, since I've been driving it more, I've happened by him a few more times. Each time he eagerly waves and smiles. It's great to have made a connection with a neighbor, I hope to talk to him more and maybe offer a ride someday. But the best thing is that he's seeing an electric car driving around the neighborhood on a regular basis, and he has a positive attitude about it. I hope that it's situations like this that will slowly help to convince more and more people that an electric car IS a viable option for some.
I'm still averaging about 325 Watt/hours per mile, which isn't horrible, but I'm pretty sure that will get better with the modifications I've planned for this fall. New springs in the front, fix the alignment and replace the differential's fluid are what I have in store as soon as the weather really starts cooling off.
There is one small thing that's been driving me crazy, and that is a rattle coming from the rear of the car. A rattle whose source, I've not been able to locate. It only happens when I'm heading over bumps, so at least it's not constant. I've looked for it repeatedly, driving the car up on the ramps and poking and prodding, but with no luck. It has a real tinny sound, so it's something small, and I thought I knew exactly what it was. It sounds like one of the clamps used to compress the batteries in the rear battery box is loose. But I've checked them all, and they are all nice and tight.
It's definitely coming from the back end though. The funny thing is, no one else notices it until I point it out. Then they all say something like "It's not that bad." They're right, it isn't, but it drives me nuts. I'm going to have to drive up the ramps again and really give the back end a thorough inspection. I'm not worried that anything is going to fall off or come undone. I used self locking nuts on all the connections in the car; the kind that can't spin off on their own. Eventually I'll find it. I just hope it's before I go mad.
I'm going out to the Diamondbacks baseball game tonight with a friend. I'd love to drive the car there, but the heat would make that an unpleasant drive. The real sad thing is that the ball park has removed their electric car parking spaces! They had 2 spaces in one of the closest parking structures, right up front, with charging stations and everything. I called to find out if they were still there and what was involved in using them, only to be told that they'd been removed. Sadly, the last time I went there, I found they had indeed been turned into handicapped spaces. *Sigh* I can't really blame them, they were empty every game, but what lousy timing!
Wednesday, August 18, 2010
Tuesday, August 10, 2010
Interesting Results
Over the weekend, I ran the final test (for now) on the high voltage system. I hooked up the last piece of equipment to be tested, the DC to DC converters, and let the car sit for 3 days. By the end of the three days, the Link-10 showed that 2.18 kW-hs had been drawn off the pack. For those of you keeping track, you'll recognize that number as being very close to what we've seen in the past. Indeed, previous tests have all come up showing 2.15 kW-hs over the same time period. I'd mentioned that I expected this test to be a bit different because the fans for the DC to DC converters run continuously due to the ambient air temperature. So, at first glance it looks like we're seeing that difference. The interesting thing is what happened when I charge the pack.
On prior tests, the meter showed that the pack had lost 2.15 kW-hs, only to find when I charged the pack it would only accept around 200 W-hs. When I've worked out the math each time, I found that the Link-10 was introducing a about a 700 W-h per day error. If you want to be precise, it's actually 650 W-hs, but I rounded up 700 because it's easier for me to remember and for a few other reasons that would simply put you to sleep if I enumerated them.
Anyway, this time proved to be a bit different. I plugged in the car, started up the charger and stood there waiting for the charger to indicate it was done. I figured it would take 5, 10 minutes max. Well, after waiting for 15 minutes, and watching over a 1 kW-h be pushed to the pack, I realized that this wasn't going the way I'd expected. By the time the charger finally kicked off, it had pushed a total of 1.53 kW-hs into the battery.
Even though the Link-10 showed nearly the same draw over the 3 day test as it did on every other test, there had actually been a real draw off the pack that amounted to 511 W-hs per day! I'll talk about what the real power draw means to me and the car in a moment, but for now lets talk about the meter. The only problem is that I'm not so sure I can put it into words.
Essentially what we see is the meter failing to register the draw off the pack. Arguably, and presumably, if you increased the draw up to that magic 700 W-h per day error that seems to be inherent in the meter, the meter's reading wouldn't change much. For now, we can only speculate that would be true. What would be interesting to see would be if you increased the real draw on the batteries up to 800 W-hs per day. Would the meter begin to register that and show the real number? It's interesting to speculate, but I have no idea for now.
So what does the 511 W-hs per day that the DC to DC converters draw mean to me and the car? First, I'd like to know how much of that we can attribute to the fans. I can't easily get to the fans to see what their labels say with regards to power draw, but they seem to be ordinary 80 mm 12 VDC computer fans. One that I have laying around here says it uses .075 amps at 12 VDC. If we use those numbers (which are close enough for now), keeping in mind we have two fans, that comes out to a total of 43 W-hs per day. That seems like a pretty small fraction of the 511 W-hs that is actually being consumed. I can only assume that the remaining 468 W-hs is being gobbled up by the DC to DC converters as some sort of offering to the gods of inefficiency in the form of heat.
I think what that means is that it really would be worth while to look at turning the DC to DC converters off when the car is off. You may remember that I looked into that a couple months ago, installing a couple relays to turn the converters off when the car was off, and I ended up welding the relays shut. I contacted Ryan Bohm at EV Source and told him my dilemma. He recommended an "inrush limiter" for each of the converters. I ordered them and have them here. They really should be installed in the unit itself. Only downside there is that I have to take the converters out of the car to do so. Another task to add to the list of things to do. Mean while, the car still runs great and remains fun to drive.
On prior tests, the meter showed that the pack had lost 2.15 kW-hs, only to find when I charged the pack it would only accept around 200 W-hs. When I've worked out the math each time, I found that the Link-10 was introducing a about a 700 W-h per day error. If you want to be precise, it's actually 650 W-hs, but I rounded up 700 because it's easier for me to remember and for a few other reasons that would simply put you to sleep if I enumerated them.
Anyway, this time proved to be a bit different. I plugged in the car, started up the charger and stood there waiting for the charger to indicate it was done. I figured it would take 5, 10 minutes max. Well, after waiting for 15 minutes, and watching over a 1 kW-h be pushed to the pack, I realized that this wasn't going the way I'd expected. By the time the charger finally kicked off, it had pushed a total of 1.53 kW-hs into the battery.
Even though the Link-10 showed nearly the same draw over the 3 day test as it did on every other test, there had actually been a real draw off the pack that amounted to 511 W-hs per day! I'll talk about what the real power draw means to me and the car in a moment, but for now lets talk about the meter. The only problem is that I'm not so sure I can put it into words.
Essentially what we see is the meter failing to register the draw off the pack. Arguably, and presumably, if you increased the draw up to that magic 700 W-h per day error that seems to be inherent in the meter, the meter's reading wouldn't change much. For now, we can only speculate that would be true. What would be interesting to see would be if you increased the real draw on the batteries up to 800 W-hs per day. Would the meter begin to register that and show the real number? It's interesting to speculate, but I have no idea for now.
So what does the 511 W-hs per day that the DC to DC converters draw mean to me and the car? First, I'd like to know how much of that we can attribute to the fans. I can't easily get to the fans to see what their labels say with regards to power draw, but they seem to be ordinary 80 mm 12 VDC computer fans. One that I have laying around here says it uses .075 amps at 12 VDC. If we use those numbers (which are close enough for now), keeping in mind we have two fans, that comes out to a total of 43 W-hs per day. That seems like a pretty small fraction of the 511 W-hs that is actually being consumed. I can only assume that the remaining 468 W-hs is being gobbled up by the DC to DC converters as some sort of offering to the gods of inefficiency in the form of heat.
I think what that means is that it really would be worth while to look at turning the DC to DC converters off when the car is off. You may remember that I looked into that a couple months ago, installing a couple relays to turn the converters off when the car was off, and I ended up welding the relays shut. I contacted Ryan Bohm at EV Source and told him my dilemma. He recommended an "inrush limiter" for each of the converters. I ordered them and have them here. They really should be installed in the unit itself. Only downside there is that I have to take the converters out of the car to do so. Another task to add to the list of things to do. Mean while, the car still runs great and remains fun to drive.
Friday, August 6, 2010
A Quick Recap and A Few New Objectives
We're back from vacation and feeling great. Northern Arizona is beautiful country.
For those of you following along, you know I've been trying to sort out some apparent drain on the high voltage battery pack when the car is off. To do so, I've decided to test each, individual component, adding them one at a time to the system to see if I could determine the culprit.
What I was seeing, before the motor problems, was that when the car was sitting in the garage, off (or anywhere else for that matter), the Link-10 meter would report that approximately 1 kWh per day was being drawn off the pack. Through careful testing, I've discovered that the Link-10 is responsible for about 700 W/hours of that. That leaves about 300 W/hours yet to find. I say "about" because I didn't track the drain that carefully. It's just my recollection that it was about 1 kWh.
Anyway I've tested all the components, except for one, and found each draws no measurable power from the pack. Even the Link-10. It reports 700 W/hours per day, but it doesn't really use anywhere close to that. The only thing left to check is the DC to DC converters. Well, until summer ends, and the thermostat in the converters is happier with the air temperature, any test is not going to duplicate what I saw back in February and March. But I guess that's not entirely bad.
I've decided I'll go ahead and run the test with the DC to DC converters hooked up and running, even though the cooling fans will be spinning constantly the whole time. I'll still get some data, and it could be useful. I'll keep you posted on that.
By-in-large though, I think I've got most of what I was looking for. I know that the apparent draw off the battery pack, when the car is off, is a phantom. It doesn't exist. I wish the inaccuracy weren't there, but it is.
Now, there are still a few things that I need to do to the car. Some more important than others. I thought I'd share them with you now.
For those of you following along, you know I've been trying to sort out some apparent drain on the high voltage battery pack when the car is off. To do so, I've decided to test each, individual component, adding them one at a time to the system to see if I could determine the culprit.
What I was seeing, before the motor problems, was that when the car was sitting in the garage, off (or anywhere else for that matter), the Link-10 meter would report that approximately 1 kWh per day was being drawn off the pack. Through careful testing, I've discovered that the Link-10 is responsible for about 700 W/hours of that. That leaves about 300 W/hours yet to find. I say "about" because I didn't track the drain that carefully. It's just my recollection that it was about 1 kWh.
Anyway I've tested all the components, except for one, and found each draws no measurable power from the pack. Even the Link-10. It reports 700 W/hours per day, but it doesn't really use anywhere close to that. The only thing left to check is the DC to DC converters. Well, until summer ends, and the thermostat in the converters is happier with the air temperature, any test is not going to duplicate what I saw back in February and March. But I guess that's not entirely bad.
I've decided I'll go ahead and run the test with the DC to DC converters hooked up and running, even though the cooling fans will be spinning constantly the whole time. I'll still get some data, and it could be useful. I'll keep you posted on that.
By-in-large though, I think I've got most of what I was looking for. I know that the apparent draw off the battery pack, when the car is off, is a phantom. It doesn't exist. I wish the inaccuracy weren't there, but it is.
Now, there are still a few things that I need to do to the car. Some more important than others. I thought I'd share them with you now.
- Get the front end ride height adjusted.
- Get the front end aligned to remove any toe-in.
- Replace the differential fluid with Red Line (I did the transmission during the main build).
- Add an expansion chamber for the Zilla's coolant. You read that right. I didn't put one in when I was building the car. I realize now that wasn't the smartest thing, so feel free to mock me.
- Fit and adjust the v-belt for the compressor.
- Remove the AC lines and have them redone.
- Install a rubber membrane to the underside of the hood (bonnet, for my European friends) to keep the battery terminals off the steel in case of an accident. Let's hope that turns out to be a complete waste of time.
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