Post-balancing Distance Calibration

I have been (properly) balancing my lithium cells for a number of months now. I hate to say it, but the time before that I wasn't pushing the upper envelope of charge high enough for all the cells to get fully recharged. That meant that if I went for a significantly longer distance than I normally do, I would risk an over-discharge alarm on some of my cells (< 2.5 V).

Luckily, I never went that far.

Now I believe my pack is happily balanced, being pushed to ~183V (~3.52VPC) on every charge for the last few months (full charge voltage is 3.3V). This weekend I started to take another look at my range, and start *really* using my amp-hour meter to see how far I can really go. With lead acid batts, you're supposed to only use up to 50% of the charge if you want them to last. With lithium batts, it's up to 80% (80 of the 100 Amp-hours in my case).

Some data points from this weekend:

1) 28.2 miles, half freeway driving, half not. 51.5 Amp-Hours expended. No BMS alarms, no performance differences at all at "halfway". Great! On to data point #2...

2) 32.5 miles, ALL freeway driving, quite fast in windy conditions. 65 Amp-Hours expended. Again, no BMS alarms and no noticeable performance difference at the end of the drive!

Inching toward the mythical limit of 80 Amp-hours! I want to be careful when establishing these 'confidence' points, because I don't want to get stranded or cause harm to the batts. Good news is, because of data point #2 I now know that I can confidently expend 65 AH without getting stranded - that's about three times my daily commute!

Has it been THREE years?

I just realized that I have been driving Electro for three years! The maiden voyage (first with lead acid batteries) was back in August 2008. 6,200 gas-free miles since then and going strong.