Growatt battery config?

[jsnbrgg]

Hello. I have an 8s configuration, 280ah battery bank built running an Overkill Solar BMS. These are new CATL cells, LifePo4. Top balanced and full charge. 24v. So I’ve connected these to a Growatt 3000, and I’m wondering what I should set my battery charge voltage, low dc cutoff voltage, and full charge voltage settings to? Any other settings I need to set on the Growatt out of the box? Thanks!

 

[BentleyJ]

I find it easier to think in terms of cell voltages then multiply those values as necessary for 12, 24 or 48V systems.
LiFePO4 chemistry has a published (depending on the source) absolute min-max range of 2.0V to 4.2V. Under normal operating conditions they should never approach these limits.
The low voltage cut out on the inverter should be set to 2.6 to 2.8V per cell (20.8 to 22.8V) and the BMS low voltage disconnect should be set to 2.5V per any cell. The BMS should never have to disconnect if the inverter is set correctly and stops pulling current before a cell gets down to 2.5V.

I find it curious that many battery sellers recommend charging at 3.60 to 3.65V per cell and then set the BMS high voltage disconnect also at 3.65V per cell. This is just asking for an unnecessary BMS shut down. LFP chemistry can be charged to 95+ SoC at 3.45V given enough absorption time. Its just not necessary to charge at those higher voltages unless you have a special situation where full charge needs to be achieved in a short time period. Constant Voltage charging (Absorption cycle) should be set to 3.50 to 3.55V per cell on the inverter and the BMS high voltage disconnect can be set from 3.65 to 3.8V per cell. Other may disagree but in bench testing I have had no problems with LFP cells and short excursions to 3.8V during charging.

As far as current, the Inverter should be set to limit charge current to 0.2 to 0.3C charge rate. For Example, 280Ah battery should be charged at 56A to 80Amps. The BMS over current protection would normally be set at 100% of the BMS current rating or 1C which ever is the lesser.

 

[Shawn Hayes]

Hello. I have an 8s configuration, 280ah battery bank built running an Overkill Solar BMS. These are new CATL cells, LifePo4. Top balanced and full charge. 24v. So I’ve connected these to a Growatt 3000, and I’m wondering what I should set my battery charge voltage, low dc cutoff voltage, and full charge voltage settings to? Any other settings I need to set on the Growatt out of the box? Thanks!

How does the overkill communicate with Growatt? RS 485? Any pictures of that setup?
Looking at solar to my out building/work shop, wanting to use Growatt and some kind of BMS with 280ah cells that I have.

Thanks