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Renogy 3000W Inverter Charger Profile for LiFePO4

gongloo

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I've paired a Renogy 3000W Inverter Charger with 3x Renogy 100Ah Smart LiFePO4 batteries. The inverter/charger manual has this to say about the 'Lithium' charge profile:
When battery voltage reaches 14.7V charging will stop. When battery voltage drops below 12.5V charging will resume.
From what I can read, including in their own battery manual, 14.7V is quite high for LiFePO4. Quoting said battery manual:
During standard charging, the battery is first charged at 20A constant current until the battery reaches 14.4V. Then, the battery is charged at a constant voltage of 14.4V while tapering the charging current. Charging is considered complete when the current is less than 2A. However, leaving the battery on float will continue to balance the cells and will not harm the battery.
Forgive my questions here, being a relative beginner, but is it possible that the BMS inside each battery is regulating down the voltage (and current) as necessary to charge safely at up to 14.4V as the battery manual states? Should I set up a custom charge profile on the inverter to avoid charging at too high a voltage?

Thanks in advance!
 
No, the BMS doesn't regulate... anything. It's job is to monitor cell voltages, overall battery voltage, current, temperature etc. At face value Renogy's inverter charger does not do float at all. It simply pulls up to 14.7V and turns off the charger output until the battery drops below 12.5V, at which point it presumably turns back on and pulls up to 14.7 again. While that may cause continuous cycling of the battery it won't overcharge it. So long as 14.7 is below the BMS trip point, you'd hope Renogy have ensured this given it's all Renogy branded, it should be OK.

Many people set up to have float charge not because the lifepo4 needs it but to supply the load directly from solar rather than tapping the battery all the time. In these cases you will find the float voltage is often at 13.5V (or suitable multiple of).
 
Thanks!

From my read of the inverter/charger manual, I can set it to float at a given voltage, just not in Lithium mode. That sounds like what I'd want, since I would like the battery to stay topped up whenever on shore power. Is that a bad idea?
 
Unless you have a load on the battery there is no need to keep any sort of charge current applied as the self discharge is quite low for a lifepo4 battery. If you do have a load on the DC side / battery then that's a fair thing to do just make sure the float voltage is 13.5V (or suitable multiple of). 13.5V is generally considered low enough to not cause any problems for a battery that is being discharged to some degree daily.

If you do plan on a custom setting check that your charger does actually come out of absorption stage charging. If it relies only on tail current and you have a load on the system it may never come out of absorption stage.
 
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