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Old 12-29-17, 04:31 PM   #112
creeky
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Well. I got an email earlier this week from one of my fellow chevy volt experimenters. Not sure what happened but he had his cells go wildly out of whack.

After some months of no real voltage change this happened.

(Note: For all measurements, the module was almost fully charged, to within .5 V of 48 volts. The fellow, we'll call him A. Has 1 module that he uses in his tiny house for lights, radio, monitoring. I cannot say there were no external factors influencing the cell voltages [ie. putting a load on just one cell through a cell voltage monitor or ...])

As of 48 hours ago his cells measured:

1st 6 cells Diff=.05v
2nd 6 cells Diff=.3v

He uses a 6S monitor. It has proven reliable and accurate, verified with a voltmeter.

.3v is a lot. .05 is when I like to start balancing for sure.

Solution:

I rented him a "redwing" bms and after 24 hrs he reports

24 hours ago:

1st 6 cells Diff=.06v
2nd 6 cells Diff=.1v

Today he reported:

1st 6 cells Diff=.042v
2nd 6 cells Diff=.023v

Hmmm. I've gone 16 months without any real shift in cell balance/voltage variance. Can anyone else report on this?

Very glad to have the BMS to reestablish safe voltage balances. And let this serve notice to anyone using Volt modules. Monitor your cells!
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