diy solar

diy solar

Parallel BMS's to Buss Bar

jerrywc

New Member
Joined
Jan 20, 2021
Messages
10
Hello,
In my current 12 volt AGM setup I use system buss bars. Everything is connected to them, battery bank, inverter, 2 charge controllers, fuses, shunt and some 12 volt loads. If I have 16 cells 4S4P LiFePO4 with a BMS for each 4S. I'm wondering if there is any reason I could not just hook up each BMS and the 4 Positives to the buss bars?
I'm trying to figure out the best way to wire 4 BMS's in parallel.
Thanks
Jerry
 
Last edited:
Will the batteries each have their own shunt?
If yes, then you should be able to attach both batteries to the system busbars.
You can watch the battery monitors to make sure the share the charge and discharge equitably.
 
Thank You, Sorry I misspelled 4S4P. Do I need 4 shunts? The only reason I have one is for my battery monitor. I was thinking that the BMS's with bluetooth would take care of that.
Jerry
 
Thank You, Sorry I misspelled 4S4P. Do I need 4 shunts? The only reason I have one is for my battery monitor. I was thinking that the BMS's with bluetooth would take care of that.
Jerry
4s4p is really just 4 12.8 volt batteries.
If you want to connect all the batteries to the system bus bar and you want to make sure they all charge/discharge equitably then 4 shunts required.
The alternative is to connect all the batteries to their own busbar. then you can use one shunt but you won't be able to determine how equitable the charge/discharge is.
 
I don't under stand, What are these 4 shunts connected to, Is there another piece on hardware needed for the shunts? Sorry, but you need to make it simple. Thanks
Jerry
 
Here is a system topology with all batteries attached to the system bus bar.
Code:
key {
    | = bus bar
}
system {
    pos {
        |<->fuse<->battery1
        |<->fuse<->battery2
        |<->fuse<->battery3
        |<->fuse<->battery4
        |<->inverter/charger
        |<-solar_charge_controller
    }
    neg {
        |<->shunt<->bms<->battery1
        |<->shunt<->bms<->battery2
        |<->shunt<->bms<->battery3
        |<->shunt<->bms<->battery4
        |<->inverter/charger
        |->solar_charge_controller
    }
}
Here is a system with one shunt and 2 sets of bus bars.
Code:
key {
    | = bus bar
}
system {
    pos {
        |<->batteries
        |<->inverter/charger
        |<-solar_charge_controller
    }
    neg {
        |<->shunt<->batteries
        |<->inverter/charger
        |->solar_charge_controller
    }
}
batteries {
    pos {
        |
        |<->fuse<->battery1
        |<->fuse<->battery2
        |<->fuse<->battery3
        |<->fuse<->battery4
    }
    neg {
        |
        |<->bms<->battery1
        |<->bms<->battery2
        |<->bms<->battery3
        |<->bms<->battery4
    }
}
 
Thank You So Much
Should the amp rating of the shunt match the BMS?
Jerry
 
Last edited:
Back
Top