Trying to understand BMS on the AC200Max

Product Discussion BLUETTI AC Series
1

I have AC200Max with a D050S, and B230. When the batteries hit 100% the AC200 turns off the PV connection and the D050S connection. It then appears to discharge the batteries to 99% and then recommences the PV connection and the D050S connection. AC inverter is on, load 220-275w

Whilst getting close to 100% the AC200Max appears to reduce the PV input.

Does the AC100MAX use the PV input to power the inverter AC when batteries are 100%, or does it cycle the batteries down and then recharges, or is this something the BMS needs to do for something. I rarely hit 100% with batteries so I do not know

At the time of 99% PV 300-400w, D050S 150-170w and AC Inverter output 230W

Any insight would be appreciated.

1 Like
2

Hi @EyesUp ,
This is normal, because when it is full it will turn off the PV, otherwise it will be overcharged.
Then when the power drops a little, the PV charges a little more. Then it drops to 99% and can be charged again until it is fully charged.

3

Thank you for reply and confirmation.

4

A way around this might be to treat the onboard battery as a sacrificial unit to all these charge/discharge cycles. It will still be viable in this role for a very long time. Then have separate b230 or b300 batteries that you disconnect once fully charged, then only re-connect them for discharge at times when there is little to no PV input.

Certainly a lot less convenient than having the system shutting off PV power to the battery only at 100% charge vs. shutting PV power off entirely. But it would keep the cycle rate on the external batteries to the minimum required.