[QUOTE=firestation12;531100]
Quote:
Originally Posted by WDPatterson
Everything you said is correct, except for the fact that the BMS will actually operate on cells in a series. Depends on how many cells are in series. If you have four cells operating at 3.65 volts, you'll get a total of 14.6 volts from the charger. The BMS will shut everything off when it gets to that point. Charger will be taken out of line. Battery will settle, balance, and then go back into operating mode when there is a load on it..
The BMS does indeed monitor the cells in a series configuration. However, the parallel comment referred only to top balancing the cells to assure all reach the same peak voltage at inception. The idea is to create a battery wherein all cells reach the high point and low point cutoff voltages at the same time. Personally, I’ve not seen resting voltages above 13.3 at full charge for a 4 cell “12 volt” lithium iron phosphate battery. 14.4 is the typical bulk charge voltage preprogrammed by Renogy and Victron on their solar controllers. Some allow a custom charge profile to be user programmed.
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Sorry. I had a typo, and didn't check my work until this morning. Thanks for the reply. Each cell gets charged at 3.65 volts, for a total of 14.6 volts at the charge controller. That's the top charge, where they all balance. That's what you do with Lithium Iron Phosphate Batteries.
The charge controllers will keep pushing that, the BMS will regulate. The BMS will stop charge, and shut off the CMOS at 14.6.
Once you take the charge off, the battery will hover at 14.6, and slowly settle to its operating voltage. That's how it works. And, if you do it that way everyday, using the Sun as your power source, those batteries will maintain and balance correctly. Otherwise, any lower voltage, and you simply don't get your batteries topped off.