JK BMS & AIO Inverter comms. - Does charging current decrease at high SOC ?

[meetyg]

Let's say I have a JK BMS connected to an inverter with communication between them.
Will the JK throttle down the inverter's charging current at a higher SOC, or will it allow the inverter to charge at the maximum charge current set at inverter/BMS ?

The reason I'm asking is because I would like the inverter to charge up at a higher rate when SOC is low, but slower at higher SOC to enable better balancing.

I was wondering if it's worth setting up JK BMS communication to the inverter, which I don't have setup currently.

Thanks.

 

[AshleyL]

Nope......the current flow will naturally slow down as the battery voltage approaches the charger voltage.

 

[RCinFLA]

The object of communicating with charger is to back down charging current rate when BMS detects a single cell is approaching overvoltage limit. This prevents a total charging shutdown due to a single cell hitting high voltage limit, while other cells may not have achieved full charge yet.

At lower charging current it slows the rate the highest voltage cell moves toward overvoltage limit while allowing balancing circuitry to work longer to balance cells' state of charge out.

The rate at which a cell approaches overvoltage limit depends on charging current. Without communications to reduce charging rate as a cell approaches its overvoltage limit, a high charging current will give less time for BMS balancing before an overvoltage trip shuts down charging path in BMS.

In the best case, when balancing current capability of BMS is equal or greater than the charge current rate there cannot be a cell overvoltage trigger. The BMS balancer will bleed all the charging current around the cell approaching overvoltage in this case preventing overvoltage trigger by that cell. This allows other cells that have not reached full charge to continue charging, be it at a lower current rate.

 

[meetyg]

The object of communicating with charger is to back down charging current rate when BMS detects a single cell is approaching overvoltage limit. This prevents a total charging shutdown due to a single cell hitting high voltage limit, while other cells may not have achieved full charge yet.

At lower charging current it slows the rate the highest voltage cell moves toward overvoltage limit while allowing balancing circuitry to work longer to balance cells' state of charge out.

The rate at which a cell approaches overvoltage limit depends on charging current. Without communications to reduce charging rate as a cell approaches its overvoltage limit, a high charging current will give less time for BMS balancing before an overvoltage trip shuts down charging path in BMS.

In the best case, when balancing current capability of BMS is equal or greater than the charge current rate there cannot be a cell overvoltage trigger. The BMS balancer will bleed all the charging current around the cell approaching overvoltage in this case preventing overvoltage trigger by that cell. This allows other cells that have not reached full charge to continue charging, be it at a lower current rate.

So is this true for the JK BMS (B2A8S20P) ?