New to LiFo4. LiTime 140Ah 12.8v states a required charge voltage of 14.2 ±-.2v Optimally 14.4 is advised. No Float is also specified.
My IP22 12/30 has a LiFo4 setting pre-configured but maintains a Absorption charge of 14.2v with up to 30A current and a Float state follows absorption. I am not able to find a way to ‘edit’ these settings.
If I create a user defined program for 14.4v Bulk/Absorption and no Float state is the charge curve going to emulate the pre-set LiFo4 program? I believe that the mostly linear charge characteristic CC/CV is necessary for LiFo4 and maintains nominal charge voltage while delaying a declining the current value?
Your assumption is ok, you can set a 14.4V charge voltage, like LiTime advises for their battery.
A LFP cell can handle 3,65V max, times 4 = 14,6V. But it’s advised to keep the cell voltage a bit lower, looking at lifetime and maybe safety.
If you also have secondary chargers for the battery, like a PV installation with MPPT, you should give them the same charging settings. Otherwise one will work harder, making the other do nothing.
I would recommend to go not higher then 14,0V absorbtion voltage. This would already be 3,5V per cell. At >14,0V you should be sure, that a single cell is not already too high while the battery is still e.g. at 14,2V. In this closed batteries without single cell voltage readings, I would not stress the cells too much.
I would also expect the balancer (if there is one at all) is also not too strong, so a too high cell will not be balanced fast enough.
So with my user pre-set I can assume that the constant voltage and trailing current charge algorithm CC/CV is emulated just as the pre-set algorithm for LiFo4 Victron program.
Yes. In ‘expert’ mode you can set all kinds of different parameters, but most important are the absorption voltage and the absorption time and tail current. I would strongly suggest to choose 3.45V per cel as max, that’s 13.80. That’s enough to get the cell fully charged, if you have enough time to absorb. Set the absorption time to at least 1 hour and the tail current low (around 2A). With these settings there is almost no stress on the cell and you get it fully charged.
(higher voltages are nonsense and ‘old’ habbits. With the right absorption time at 3.45 there you get the cell fully charged, lot’s of prove that after that the cell won’t absorb any more current if the voltage is raised to 3.65).
