I have a Victron EasySolar-II connected to a Voltgo 24v LiFePO4 battery (with BMS).
The Voltgo manual has a table with recommended voltages for bulk and absorption charging. According to the manual, there is no need for float charging:
LiFePO4 batteries only require those two [bulk and absorption] stages of charge, including constant current charge and constant voltage charge, which is called bulk charge and absorption charge.
In the VictronConnect app lithium battery settings, there are fields to enter recommended battery voltages for float and absorption, but not bulk. This means that I cannot set the Easysolar-II to charge at the voltages recommended by the battery manufacturer.
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Also, as a side note, my Easysolar-II spends most of the time in float charge, which is is apparently not needed for LiFePO4 batteries.
Can somebody please explain the discrepancy? What is going here? How can I reconcile the voltage recommendations from the battery manufacturer with the VictronConnect app?
I’m sure there are a lot of thoughts here on the forum. So I am prepared to be contradicted and if necessary corrected. Essentially your absorption setting will set the bulk and absorption charging. They will be the same in a lithium battery. If the manufacturer wont give you a float value I would set it to around 3.4-3.45 V per cell for around 27.2-27.6 based on other battery manufacturers recommendations. It should be safe.
Correct. Bulk and absorption are the same target voltage.
The difference between the two stages is the amps drawn by the battery.
For some batteries they have a bulk and an ‘equalisation’ charge which is really absorption as that is a balance charge. (Low amps constant voltage)
When the statement is made that lithium doesn’t need a float charge what is meant is they are not like lead acid that needed a bit of current trickling in to maintain the voltage at float. But many manufacturers drop the voltage at this stage so as to hold the battery cells at a lower voltage per cell.
You can set the two the same in victron connect. Or within 0.1/2v of each other if that is what the manufacturer wants (so the float will really be the bulk target which is where it will be after balancing)
