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southsideph avatar image
southsideph asked

New to Lifopo4 - question

Just asking for thoughts realitively new to Lifopo4. Just replced AGM with Lifopo4. Default setting is to auto rebalance at 3.2V per cell which is about 10% SOC. But my discharge floor doesn't go below 20% so batteries effectively never rebalance.

  • What does advantage does rebalencing give?
  • What optimum SOC should you rebalance ( can calculate voltage)?
  • How often should you rebalance?
Lithium Battery
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3 Answers
snoobler avatar image
snoobler answered ·

What battery(ies)?

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southsideph avatar image
southsideph answered ·

The batteries in this instant are Stirling Power 2 x 24V 150AH, I wanted to use pylontech US2500 but availability/if they are going to be available. The advantage of the Stirling Power you can connect them in series to 48v so when upgrade to 48v system then the batteries will still be relevant. The only issue is there is no integration with the Victron setup.

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snoobler avatar image
snoobler answered ·

Generally speaking, most LFP batteries are top balanced. A typical scheme is as follows:

If cell voltage deviation is > 0.02V

during charge only

only above 3.40V/cell

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kevgermany avatar image kevgermany ♦♦ commented ·
@SouthsidePH

To add

Looks like there are some misunderstandings. The Sterling (and Pylontech) will rebalance automatically. 20% SOC is a recommended max discharge for extended life. Preferably keep the batteries higher than this.

As rebalancing is carried out by taking current from the high cells, it's prevented by the BMS at low voltages.

On frequency, bring the batteries up to 100% at least monthly.

Voltage is a poor way of assessing SOC, much better to use a shunt based system. Afik the Pylontechs have an internal shunt, many other lithium use voltage. If you want accurate values, check with battery supplier if there's a shunt, if not consider a shunt like the smartshunt or BMV712.

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