Batteries with different state of charge?

[houseofancients]

I didn't address this.

The BMS don't regulate anything. They are simply observers and drawbridge operators with a different bridge for each direction of traffic. They watch for things to go out of limits. When it does, they raise the drawbridge prohibiting the traffic in the offending direction.

The BMS in no way influence how much any battery discharges or charges beyond cutting it off if it's too much.

no entirely true, some bms'es do limit the charging or dicharging current based on SOC ..
Seplos is one of those, and given the diode issue, iḿ convinced they are.

@OP , when you are there , any change to disconnect some batteries to manually bring up to the same SOC , or as close as possible ?
since you have breakers, this could be done by switching one off everytime untill the battery is let's say 85% , enabling the next one, shutting down the breaker for the one that is 85% , or a similar process ?
next to that, the seplos bms calculates the SOC based on a full charge and discharge cycle, which means the battery has to charged too 100% and Discharged to 100% ( both shutoff) , and those numbers are used to calculate the SOC..
i am not sure rosen actually did that prior to shipping, but given you have replaced the BMS's , i would expect them to not be using the correct SOC numbers

 

[sunshine_eggo]

I never had them working properly before the BMS boards got changed. Essentially batteries started dropping dead from day one, so they shipped me new BMS boards (since the bad diodes was a known issue) and I installed those new boards myself.... but never did any type of reset on them

I would expect the shutdown process, replacement of BMS and restart process would be the same as a reset.

 

[sunshine_eggo]

no entirely true, some bms'es do limit the charging or dicharging current based on SOC ..

As an aggregate, yes, but not individually. The BMS can limit the total charge output of the charger, but it can't influence how much any one battery gets and discharge limits are a different beast altogether. It's binary there too.

 

[houseofancients]

As an aggregate, yes, but not individually. The BMS can limit the total charge output of the charger, but it can't influence how much any one battery gets and discharge limits are a different beast altogether. It's binary there too.

individually, and based upon the aggregate a max amps is send to the inverter
these batteries communicate together, and the master of the pack communicate the aggregates to the inverter...
i updated my above post..
i think since the OP replaced the BMS's , they are working of the wrong SOC number

 

[SeaGal]

... sometimes they all discharge the same, and othertimes there will be one or two that are not discharging at all, and sometimes it's 1 or 2 not discharging as much as others.

Are the "1 or 2" that are not discharging all/as much, always the same "1 or 2" batteries? If so, connections and cable lengths would be my first area of suspicion. If the "1 or 2" are random over the 5 batteries, then something else is wrong...

 

[Scorch]

individually, and based upon the aggregate a max amps is send to the inverter
these batteries communicate together, and the master of the pack communicate the aggregates to the inverter...
i updated my above post..
i think since the OP replaced the BMS's , they are working of the wrong SOC number

so how would I correct that.... is this where the reset would come in? I saw that there is a reset button on the batteries, but havent used it.... So if I let all the batteries charge to 100%, and then hit the reset button, does that set the SOC for each battery?

 

[Scorch]

Are the "1 or 2" that are not discharging all/as much, always the same "1 or 2" batteries? If so, connections and cable lengths would be my first area of suspicion. If the "1 or 2" are random over the 5 batteries, then something else is wrong...

seems to be different batteries every time.

 

[houseofancients]

so how would I correct that.... is this where the reset would come in? I saw that there is a reset button on the batteries, but havent used it.... So if I let all the batteries charge to 100%, and then hit the reset button, does that set the SOC for each battery?

a reset doesnt recalculate the SOC, it more like a computer reset button...
there are 2 ways...
1. the best way .. for each battery do a full charge ( untill shutoff ) and discharge ( untill shutoff) , this calculates the SOC dynamically based on the cells
2. you can set the SOC manually through the software, however , with LIFEPO4 it is really hard to know the SOC, so i would very much encourage you to use the first method, and do that for individual batteries before allowing them together
this will take some time, but should get you a very accurate SOC, and thus much better performance out of your system

 

[Scorch]

a reset doesnt recalculate the SOC, it more like a computer reset button...
there are 2 ways...
1. the best way .. for each battery do a full charge ( untill shutoff ) and discharge ( untill shutoff) , this calculates the SOC dynamically based on the cells
2. you can set the SOC manually through the software, however , with LIFEPO4 it is really hard to know the SOC, so i would very much encourage you to use the first method, and do that for individual batteries before allowing them together
this will take some time, but should get you a very accurate SOC, and thus much better performance out of your system

Sweet.... I will try that out next time I'm at the location..... I may also try to run them off the battery BMS instead of the inverter BMS... I read in another post that this might be helpful.

 

[SeaGal]

Sweet.... I will try that out next time I'm at the location..... I may also try to run them off the battery BMS instead of the inverter BMS... I read in another post that this might be helpful.

Sorry if I'm having a blonde moment, but what's an inverter BMS?

 

[houseofancients]

Sorry if I'm having a blonde moment, but what's an inverter BMS?

good question..
deye/sol-ark/sunsynk certainly have nothing like a bms onboard

a bms ( battery management system) is only at the battery level, and may communicate its values and other metrics to the inverter.

@Scorch elaborate pls

 

[Scorch]

good question..
deye/sol-ark/sunsynk certainly have nothing like a bms onboard

a bms ( battery management system) is only at the battery level, and may communicate its values and other metrics to the inverter.

@Scorch elaborate pls

Dunno.... I guess I assumed that the Inverter had a BMS and was doing something since I hook up the batteries to it with a network cable, but I really don't know (Again, I am coming from a place with minimal knowledge). I also thought I read that in another post, that you can use the inverter BMS or the battery BMS (something about how the inverter BMS may not work well with Rosen batteries since Rosen uses 15 cells instead of the standard 16 cells).... but that may have been in reference to a GroWatt inverter.... I'd need to look back and see if I can find that post.

 

[houseofancients]

Dunno.... I guess I assumed that the Inverter had a BMS and was doing something since I hook up the batteries to it with a network cable, but I really don't know (Again, I am coming from a place with minimal knowledge). I also thought I read that in another post, that you can use the inverter BMS or the battery BMS (something about how the inverter BMS may not work well with Rosen batteries since Rosen uses 15 cells instead of the standard 16 cells).... but that may have been in reference to a GroWatt inverter.... I'd need to look back and see if I can find that post.

ah ..
well i think what they may have done in the growatt is disable bms communication, and set manually charge rate, volts etc..

this can be an option if you were aware to the exact settings that rosen needs per battery.
look up that post, use those settings, make sure you unplug comms cables.
bms will still protect your cells, but will not throttle down charging, so internal cell inbalance per battery may occure, that will solve over time, but may limit your total pack ah's a bit untill such time

just to be clear, your inverters have no bms.
what you are seeing on your deye display is information pass to it by the bms located in the batteries