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A cleaner way to drive

Range Test

So I charged the LiFePO4 cells to 3.4 volts each for a full charge and tested range this weekend. After 82 miles (freeway/local roads – top speed 80 mph on flat), the cells were averaging 3.14 volts each at rest. The battery manual from the manufacturer suggested that at 3.1V the batteries would have been discarged over 85%. I calibrated the INS-ZEVA-FGD11 (A Hall Effect based fuel gauge driver that lets you use the stock fuel gauge as a State-of-Charge gauge) to indicate empty at this stage.

It was a hot day at 101F today and I did not have AC in the car, so testing range today was pretty uncomfortable. As I was driving, I noticed that one of the cells was reading 0.4Vs after driving 10miles at 65 mph. Worried, I drove back on back roads at slower speeds. As soon as I got home, I took the temperature of a few of the battery terminals… ~103F. The battery manufacturer recommends that I turn on cooling fans when the terminal temperatures reach 104F, and should decrease amperage draw when temperature reaches 122F, and shutdown the controller completely when it reaches 131F.
I don’t have any additional cooling besides venting and airflow when driving on the batteries, so this is something that I need to watch out for on hot days.

I also measure the cell voltage using a multimeter and it read 3.25V. I am not sure why the cell monitor was reading 0.4V. After unplugging the cell monitor and plugging it back, it read 3.25V again. Must have been a problem with the cell log monitor (or maybe it was temperature related?). By the way, I am using cell log 8′s per suggestion from a cool friend whose been really helpful with my conversion and my decision to go with Lithium, he’s got a Honda Civic EV using the same Lithium cells.

I’m all ready for the Bar Referee appointment next week (This is where they inspect the car to verify that it has been converted to electric and that it is safe and road worthy, once this is done, I can go to the DMV and get it registered as an EV and get special HOV stickers- white ones not yellow ones for hybrids!)

Few more notes: Tried to get an alignment but the good guys at the alignment shop (Motorsport Techniques in Hayward) won’t do it because the rear wheel bearings are bad, they suggested that I replace them first before I get an alignment. They did, however, balance the tires, and that helped with the shaking in the steering wheel that I felt when driving at freeway speeds.

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Posted in Batteries, Maintanence, MR2EV, Range


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