This blog documents the restoration, and conversion, of a 1965 Humber (Singer) Vogue to a fully electric vehicle. The Vogue will be powered by an 11kW(modified), 3 phase industrial AC motor, controlled by an industry standard Variable Speed Drive (VSD) or Inverter. To be able to produce the 400 volts phase to phase the VSD will need about 600 VDC of batteries. A big thanks to the contributors on the AEVA forum:

Wednesday, November 28, 2012

Another Battery Pack Check

Following the drive described in my previous post I need to iron out why the packs pulled up a little "short".
I pulled subpack #2 out of the boot, removed the lid,  and measured all the cell pairs. Fifteen of the sixteen cell pairs were between 3.19 and 3.21 VDC. One pair was 2.98 VDC.
I removed those two cells and marked them 11A and 11B (eleventh up from the -ve end of the pack) (the cells are 10AH).
I started by charging them individually at exactly 5A and noting the time and current every now and then. Both cells took 9.45AH - they were obviously quite discharged.
I then discharged the cells individually with a 0.8Ohm load down to 2.9VDC. I got just over 9.5AH. The white LED goes out at about 2.5 volts so lets me use a quick glance while I'm working to help prevent over-discharging the cell.

Obviously both cells are fine.

I recharged the cells to 4AH and placed them back in the pack.
I then charged the pack at 3A. The charger dropped out at 3 hours and 25 minutes. That was 10.25AH. The cells I had removed (#11) were the cause of the charge stopping. They had reached 3.9V and stopped the charge.
All remaining cell pairs were at 3.33 to 3.34VDC. I left the charge current at 170mA overnight - for 7 hours (1.2AH).
Next morning, I loaded cell pair #11 with 0.8 Ohms and kicked the charger back to 3A. It charged for 40 minutes before dropping back from another cell pair getting to 3.9VDC. Most cells pairs were now over 3.5VDC.

That's a total of 13.45AH for most of the cells. The Vogue had indicated 12.19AH which appears to be about 10% out. I will check the current sensor in the Vogue with a measured current, as that is something I have just "believed" - up until now.
I have also heavily integrated (smoothed) the current sensor value in both hardware and software. Perhaps I should not - and just smooth the display value.

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