If I was to lower the absorption voltage on LiFePO4 batteries what would the affect be? it is currently set to 56.8 as standard but i'm intrigued to know.
It depends on if your cells are actively or passively balanced and the trigger voltage for the balance circuit. You can go lower for bulk/absorption but it does need to be high enough for the circuit design.
The other effect being a lower capacity stored in the battery.
From my experience and training for 16-cell LifePO4 batteries Bulk & Absorption charging rates can be the same since they are the same function with LifePO4 batteries. And, baring any difference stated by the battery manufacturer, the charging rate should be about 57 - 57.6v (remember, battery capacity while charging is 58.4v).
I have seen some folks state that the Bulk should be 57.6v and Absorption can be stepped down to 56.6v - 56.8v to lighten the incoming power on the battery.
The Float charging rate should normally be set at 54.4v (the resting 100% SOC). This comes from my 150/70 manual "During this stage the float voltage is applied to the battery to maintain a fully-charged state. When the battery voltage drops below float voltage during at least 1 minute, a new charge cycle will be triggered. "
But 56.8v Bulk setting is fine, just will take a little longer to get the batteries up to full charge. And, 54.4v on the Float will keep your battery at 100% resting SOC.
FWIW...charging control is more about voltages than length of time. Although some folks preset absorption time. But I haven't seen any benefit to that.
If you have a 15-cell LifePO4 battery let me know and I will look up those voltages for you if you would like.
50 People are following this question.