Fist of all, if this is not in the correct Categories, Please move it to the correct section.
Scenario:
I want to run the cells at 3.35v each,(Max 56.1V, 17S). But as this is quite low voltage, just barley from the “working” current, (not sure what the correct term is). So at that Voltage, the BMS cant really do great Balancing. So the chance that the battery will go out of balance is quite high.
The reason to do this is to extend battery life cycles. (Or thats the idea)
So here is my question. - Based on the the Victron Smart Solar MPPT.
Is it possible to charge the LiFePo4 batteries on the AGM setting. The voltages will be adjust to the correct voltages.
The reason for using that profile is this:
To use the Equalization every X days for Y Hours to make sure the batteries stays balanced if we use them at the 3.35V settings?
Example: Run daily at 3.35V. Equalize the batteries every 30 days and take them to 3.5V/cell and keep them there for 4 Hours just to balance the cells. - Repeat.
@neliuszeeman which BMS are you using in your system? The reason I ask is that some BMS like the JBD you can set at which cell voltages the balancing will start. Set it at 3.35V and then you have what you need.
Also, remember that even if your BMS does not support lowering the balance voltage , this should still not be too much of a worry. Any cell that is out of balance will already have a higher cell voltage and that will kick off the balancer.
Most BMS do balance from around 3.4V-3.45V if I remember correctly and that will be fine for yours cells.
But if you still want to do what you plan with the profile, then there should be no issue with that. The big thing to watch out for is to keep within your voltage profile for your battery. The BMS of the battery will manage your cells and keep them safe. You don’t need the LA profiles with Lithiums, but it will not harm them if you do use them.
thanks @Louisvdw
I dont have the cells yet. Its coming with the TTT shipment. I will also use his BMS.
Its 280A cells. The BMS only have 260ma Balancing current. I know that 260ma is ample when running the cells to 3.65v, but at 3.35v not really helpfull.
Im following Off-Grid Garage on Youtube, and he ran into a problem when he was using his 280A cells at 3.35V each. If im not wrong, he will use the same BMS as TTT.
The BMS you will get is a JBD and you can set the cell voltage at which balance will start. Make it 3.35 and any cell that is higher will be balanced.
The only problem I can see is that at 3.35V your cells can be anywhere between 45%-75% full, so the balance might need to work hard. At that voltage I cannot see that you would care much for the balance. Your BMS will have lots of time to balance.
Give it a few months. If you see that is does not work then you can try the Gel profiles.
I don’t think it will impact you much to be honest. You are only using up to around 80% of your cells. If you start with a balanced pack it will be very long time before the imbalance of a cell goes from 80% to 90%. At around 90% + you should be seeing that the cell reach 3.4V and most balancers will start around that and will pull the cell down to around 3.8V before it release the balance.
