Definitely allow the pack to balance for awhile. Particularly fresh from
the factory. Check them all with a voltmeter, not just with the BMS. You
want to be sure that everything is connected right and is working 100%
properly. Trust, but verify. Do this before and after the first few test
runs.
You should limit the first test runs to within a few blocks of your
house. You can go around the same route numerous times, but you want to
stay within walking distance. :-)
You should set the cut-off at 2.5 volts. You can set the cut off lower,
but if 2.5 works, that is a good place to leave it.
These are Chinese cells, after all. The Chinese make pretty good stuff
very very cheaply, but often the quality control is not tip top. I
typically recommend purchasing a couple of spare cells.
Bill D.
On 7/29/2014 5:43 PM, Zeke Yewdall via EV wrote:
I am programming the BMS, and am wondering what opinions people have on the
sepoints for the BMS, specifically for discharging.
24 CALB cells, 100AH, Alltrax 450 controller, DC6.7" motor, 1973 VW bug.
Elithion Lithiumate Lite BMS.
I did the first serious road test this morning, Default setttings were
100A continous, and 300A peak for the BMS to start regulating. 2.9 volt
was the low voltage cutoff, with 2.5 volts being the drop dead voltage.
It was doing pretty good for about 15 miles (60AH or so). It would cut out
under hard acceleration (380 amps or so) and kill the power to the
controller. Under sustained uphill (200 amps or so) it would also cut out
after a while, and would also engage the throttle limiting to keep it to
100A or so. I would like to set it to 150A continuous, but not sure if
this risks damaging the battery. It's going to live in a much flatter
place than I was doing the test, so maybe 100A is okay.
The big problems started about 18 miles in -- one battery started going
under 2.9 volts under accelleration, and by 19 miles in, it was severely
limiting current to keep it above 2.7 volts or so -- went to only about 30
amps, which was essentially undriveable. I either have one cell badly out
of balance (what I'm hoping for), or that's only got about 70AH capacity
instead of 100. If I can correct this one cell and bring it up to what all
the others are doing, am I safe in raising the current limits a little, if
I keep the voltage controls the same?
Opinions?
Thanks
Zeke
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