Electric Porsche!

The air wrench sounds like a good idea, but I'll probably stick with the cell phone and a wrecker. My back hurts today, just from moving the spare tire from the back seat to the front, and back again.

If I get 90 miles to 20% SoC it will be a little less than they promised me, but not enough less to raise a fuss over. That would get me to Coeur d'Alene and back, with 40 miles left over. Or C d'A plus 20 miles of giving folks rides, and home with 20 miles to spare and still have my 20% reserve. We'll see. Paul did tell me that the motor is stiff when new, and will loosen up with use.

The car could have been built with a 110-volt charger. It would probably take about 18 hours to recharge from empty. Mine should take about 4 or 5 hours. One of the reasons I requested 125 miles was so that I would never have to charge the car away from home or during the day. I figured I'd never want to drive over 100 miles in one day, and probably never more than 75, unless I was on a road trip, and then I'd need a 400-mile range or drive the stinker. If I get less than 75 miles with a 20% reserve I'll be complaining.

My Kill-a-Watt meter is 110 volt and only goes up to 15 amps. I have nothing for this car. However, some time probably next week the electrician is going to come over and put a meter on it and measure the amperage draw. Actually, it's possible that my e-meter (in the car) may show charging amperage at the battery pack (not into the chargers). While driving it shows amperage draw, total amp-hours consumed since last re-set, percent SoC based on how many amp-hours you tell it you have and its measurement of usage, and maybe other related stuff. I don't know if it works in reverse during charging.

 

VERY preliminary numbers suggest a range of 65 miles to dead empty, or 52 miles to 20% SoC, which is supposed to be safe for these batteries. That is very disappointing. At 52 miles safe range this car would not do what I need it to do. On Tuesday I'll be able to make some more reliable tests, since the charging cable should come Monday and I'll be able to charge over night.

 

I'm afraid run-flat tires would cut 50% off my range. The car may be a chick magnet, but I'm a chick repellent.

 

The charging cable arrived by UPS this afternoon. The car is plugged in. It will be all charged up by midnight, though I won't drive it until after exercise tomorrow. Exercise is more important than even an EV. Now, if that pretty check-out girl at the grocery store waggled her finger at me, I'd skip the exercise, but not for anything less, and she's probably married. She looks a lot like Sandra Bullock. I'm more likely to win the lottery without buying a ticket than to get an invitation from that girl. So exercise is still on the schedule for tomorrow.

 

I don't have a meter at the wall, but one day this week the electrician will come over and put a meter on, so I'll know the current draw at the wall. But supposedly it should be 36 amps. That's at 220 volts.

The e-meter shows current going into the battery as well as coming out. It's charging at the rate of 25 amps. Presumably the difference is charger inefficiency. It will be interesting to see the actual current draw at the wall. But that's all academic as far as I'm concerned. What I really care about is how far I can drive it.

 

First freeway test:

It is extremely windy today. I had the wind at my back going out, and the wind against me returning. I drove 2 miles to the freeway, then about 13 miles on the freeway at as close to 60 mph as I could keep it. The cruise control does not function now that the ICE is gone. Then I turned around and came back. I stopped at the Porsche dealer to show off my car, so I probably drove 1 1/2 miles off the freeway, more or less, and came back to it a mile closer to home, so for a mile of the against-wind I was on surface roads rather than freeway.

Altogether I drove 30.8 miles, roughly 25 being freeway, and of that, probably 13 was with the wind and 12 was against the wind. Of course I also had the wind against me on the surface road, but it probably has less of an effect at the lower speed.

I used 88 ah. Going by the specs they've given me: my pack is 28 kWh and is 200 ah, I used 44% of my charge, or 400 wh/Mi. This is not very good. It translates to a total pack range of 70 miles, or 56 miles to 80% DoD (20% SoC) which I've been told is safe for LiFePO4 batteries.

In coming days I will repeat the test at 55 mph and at 70 mph (the speed limit here) and on the surface roads. I'll also assess the acceleration at freeway speed.

 

Dave: My car is a 2003. The car's not new. Only the electric components, such as the motor. Paul says the motor will loosen up with use.

LiFePO4 batteries do not have a break-in. But even if they did, it would not change my numbers. Here's why: With your lead batteries you drive until the voltage drops or the power drops. The distance you've gone tells you your range. I'm doing something altogether different: I've been told that my pack holds 28 kWh and that it holds 100 ah. I have an e-meter which tells me how many ah I've used. I am not driving until exhaustion to test my range. I'm measuring my ah used over a distance, and converting that to wh.

UPDATE:

My pack was all topped off at 7:00 p.m., so I took the car out for another drive, this time on rural surface roads. Not really rural, but out-of-town roads. There are stops, but not frequently, so there's a lot of steady-speed driving. This time I held my speed between 35 and 40 mph, and I got 343 wh/Mi. This translates to a pack distance of 81 miles, or a "safe" distance (down to 20% SoC) of 65 miles.

 

I spoke with Paul. My controller is a Curtis 144-volt 1231c. My battery pack consists of 96 cells, in parallel pairs of two, for 144 volts total. The discrepancy between the contract voltage and the actual voltage arose because the higher-voltage controller he was going to use (256 v?) turned out to be unreliable. He had two blow up out of a shipment of five, and he decided the Curtis, though less powerful, was the better choice for reliability. He would not have used more cells, but he would have wired them differently had he used the higher-voltage controller.

He still says the car will get more range as the motor breaks in, and he says the batteries will break in also, though I am skeptical of that last statement.

After this conversation, I believe he was acting in good faith, but he overestimated the range I'd get. I suspect that he has less experience with LiFePO4 than I had thought, and this could be part of the problem. The car does not do what I wanted it to, but it will do what I need it to. I would not have paid what I did had I known the range I'd actually get, but I will make the most of what I have and enjoy the much greater speed and 50% greater range compared to my little Zap Xebra. The little three-legged clown car is really a fine vehicle, but the Porsche can do more.

I had asked for 125 miles of range so that I'd never have to worry about battery capacity or opportunity charging, but now I'll try to find out if the community center where my church meets in Coeur d'Alene would permit the installation of a charging spot.

 

Range test number 3. (70 mph. Sort of.)

This morning I again drove to Post Falls and back on the freeway. My intention was to maintain 70 mph. However I hit two snags with that: For the first 2 or 3 miles the traffic was going 60 and I could go no faster. More significant was the power loss:

At my turn-around, when I got back onto the freeway and intended to accelerate rapidly to my cruising speed (yes, that's inefficient, but safety trumps all) I noticed a sort of pulsating hesitation. I noticed the same yesterday and wrote it off as rough road. But today the same pulsating hesitation appeared again as I neared the end of the freeway portion of my trip. Slowing down all was well, but I could tell that I lacked power. I downshifted, and that helped, but I clearly had less power.

The obvious explanation presented itself immediately: My voltage was down. I had consumed roughly half my "safe, usable" energy (i.e. keeping 20% in the pack). The lower the battery SoC the lower the voltage and the less the power. I was surprised that at roughly 60% SoC (40% DoD) the car would be unable to maintain 70 mph, but such was the case.

I spent about 25 1/2 miles on the freeway, driving 70 as much as I could, and 60 at the start (due to traffic) and the end (due to power reduction). I averaged 435 wh/mi, which would translate to a full pack range of 64 miles, or a "safe" range of 51 1/2 miles.

But this made me realize that one amp-hour may not get me as far at the end of the pack as it gets me at the start of the pack, and my range calculations in all my tests might be high.

Next project: See if I can get the community center where my church meets (we're too small a congregation to have our own building) to install, or allow me to have installed, a charging spot. I'll pitch it on environmentalism, but I'll be up against the fact that I'd probably be the only one to use it.