balancing strategies as they relate to BMS

ArthurEld

Solar Addict
I have the BMS so we need to decide which opto coupler to order.

edit: I can try connecting the BMS to 16 of these 3.29V cells and see what info I can see in the app.
 

smoothJoey

Photon Sorcerer
I think one of these will work.
Need a buck converter to bring the voltage down as well.
The -B means normally closed so that when the bms disconnects the downstream closes.
You could also use a relay if you could find something less expensive or more suitable, does not require a buck converter.
I'm not awesome at research.
 

ArthurEld

Solar Addict
Since the BMS over voltage protection can be set to any value, I can set it to trip at 3.35V and see what it does. I have a lot of cells and a lot of volts to charge so I can do a lot of test runs.
I don't know anything about opto couplers or relays so my search probably won't help much. But I'll see what I can find.
 

smoothJoey

Photon Sorcerer
Since the BMS over voltage protection can be set to any value, I can set it to trip at 3.35V and see what it does. I have a lot of cells and a lot of volts to charge so I can do a lot of test runs.
I don't know anything about opto couplers or relays so my search probably won't help much. But I'll see what I can find.
Here is a primer.
Different use case and he is using a normally open ssr but you will get the general idea of how to use a relay with a bms to control things.
 

ArthurEld

Solar Addict
I'm transferring this back to here -

Perl:
DF11-EP2428PCFA


make 16s pack with bms

battery.pos<->|->normally_closed_relay->power_supply_s.pos
              |<-48_volt_charger.pos
            
bms<--------->|<-normally_closed_relay<-power_supply_s.neg
              |->48_volt_charger.neg

disable bms balancing
set hi cell cutoff to 3.5 volts
set high pack cutoff as high as it will go so the hi cell cutoff trips first
charge the pack with 48 volt charger until one cell trips the hi cell cutoff
disconnect 48 volt charger
set hi cell cutoff to 3.65 volts
wait until the hi cell settles to the bms resume threshold

foreach cell in cells
    connect power_supply charge leads to cell
    charge cell with power_supply
    bms triggers power_supply disconnect
    disconnect power_supply charge leads from cell
    wait until the high cell settles to the bms resume threshold
next

 

ArthurEld

Solar Addict
Charge 16s until BMS turns off 60V power supply @ 3.5V.
Leave cells connected in series.
Charge one cell until BMS turns off 3.8V power supply @ 3.65V
 
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