Feedback on adding 2 panels to my RV solar array

[culty]

Per @Rocketman, BMS don't limit current. They cut it off, i.e., if the BMS is rated for 100A and the load on the battery exceeds 100A, the BMS will cut off the load to 0A not limit it to 100A.

BMS are simply charge/discharge on/off switches with various rules for when those switches can be on or off.

Got it. The BMS used in the batteries is a custom-built BMS. It doesn't seem to have the specs listed, but I was informed that it's a 60A BMS. Assuming all batteries/BMS are functioning correctly, then having them wired in parallel with busbars would allow them to accept a much larger number for charging amperage, since that would be distributed roughly evenly across all batteries, correct?

The max charging current on the Growatt is 80A PV, 60A utility. The max current on the Rover is 30A. So max possible current across all chargers would be 110A on PV, and 170A on PV + Utility (unless I have either of those values set lower), divided across the number of cells in the bank. Am I understanding that correctly?

 

[Rocketman]

almost… (it’s per battery not cell).

110a on Pv divided by number of batteries (say 8) = 13.75a/battery.

13.75 charge current / 20ah battery = .68C

Which is way too much…

My cells say .5C max and .2C recommended by people here. I realize your cells may be able to handle more - but you want them to be safe and last a long time - so lower C rate charges are better (from what I understand) - .2 to .5C

 

[culty]

almost… (it’s per battery not cell).

110a on Pv divided by number of batteries (say 8) = 13.75a/battery.

13.75 charge current / 20ah battery = .68C

Which is way too much…

My cells say .5C max and .2C recommended by people here. I realize your cells may be able to handle more - but you want them to be safe and last a long time - so lower C rate charges are better (from what I understand) - .2 to .5C

Are your cells LI, or LFP? Do you think the headway LFP cells are just ambitious in their spec? Or do you think I can depend on it?

 

[Rocketman]

My cells are LiFePO4 - both Lishen and Fortune.

I have no idea on the other chemistries. That may be a good question for a new thread…

 

[culty]

My cells are LiFePO4 - both Lishen and Fortune.

I have no idea on the other chemistries. That may be a good question for a new thread…

I was about to post a thread on fuses and breakers. I'll post one on battery charge rates as well. Thanks for all your input @Rocketman!