Upgrading from 6v House batteries to 12v question

[PeteMcCarthy]

I am upgrading my 4 - 6v series/parallel house batteries on my 2021 Berkshire 34B to 2 - 12v batteries. My inverter/charger and solar charge controller have compatible Lithium charge profiles and I will be upgrading my BIM to be Lithium compatible too.
I would like your opinion on the correct way to wire my 12v batteries in parallel. I have attached the OEM wiring diagram (shows 6 batteries, I only have 4), the actual wiring diagram for my current system and a diagram that proposes 2 scenarios on how to wire my new 12v batteries for optimum balanced charging/discharging. I know many of you have already done this upgrade and/or have greater knowledge than I have and would greatly appreciate your thoughts.
Thanks, Pete

 

[Aussieguy]

A senerio
But to a bus bar
Then inverter solar and any other power wire from the busbar
Plus use fuse/breakers

The wiring from bus to battery must handle all combined loads you can expect to have on at one time

Breaker sized for the max load too
——————
There is also a method you can use
Connect each separate battery to bus bars using their own positive and negative and fuse
Then if a battery dies the other one can take over while you fix the any problem

Partial batteries may get outta sync a bit
But as long as they return to equal SOC / volts within a a day or so …. it is good
———————-

Do not take power from separate terminal as shown in B

 

[PeteMcCarthy]

A senerio
But to a bus bar
Then inverter solar and any other power wire from the busbar
Plus use fuse/breakers

The wiring from bus to battery must handle all combined loads you can expect to have on at one time

Breaker sized for the max load too
——————
There is also a method you can use
Connect each separate battery to bus bars using their own positive and negative and fuse
Then if a battery dies the other one can take over while you fix the any problem

Partial batteries may get outta sync a bit
But as long as they return to equal SOC / volts within a a day or so …. it is good
———————-

Do not take power from separate terminal as shown in B

Thanks for your suggestions!

 

[PeteMcCarthy]

A senerio
But to a bus bar
Then inverter solar and any other power wire from the busbar
Plus use fuse/breakers

The wiring from bus to battery must handle all combined loads you can expect to have on at one time

Breaker sized for the max load too
——————
There is also a method you can use
Connect each separate battery to bus bars using their own positive and negative and fuse
Then if a battery dies the other one can take over while you fix the any problem

Partial batteries may get outta sync a bit
But as long as they return to equal SOC / volts within a a day or so …. it is good
———————-

Do not take power from separate terminal as shown in B

Aussieguy, a follow up question if I may? My current system has a Class T 300a fuse between the battery bank (hot lead) and the feed to the inverter AND it has a 250a fuse between the battery bank (other hot lead) and the Coach Supply. Will these breakers suffice when I upgrade the batteries OR are you suggesting additional breakers be installed? Thanks again for your insight! Pete

 

[Aussieguy]

Would have to get more info on how and what fuses you got

Each wire run needs a fuse for the max amps the WIRE can handle
So if you put bigger wire you use a calculator to determine the fuse size for that lenght

Then when you run from a bus you add a smaller fuse onnthat individual wire if it is smaller gauge

I can’t do much copy paste stuff on my phone
Won’t be home for another day or so

Other members like TitanMike are a real good source too

 

[PeteMcCarthy]

Would have to get more info on how and what fuses you got

Each wire run needs a fuse for the max amps the WIRE can handle
So if you put bigger wire you use a calculator to determine the fuse size for that lenght

Then when you run from a bus you add a smaller fuse onnthat individual wire if it is smaller gauge

I can’t do much copy paste stuff on my phone
Won’t be home for another day or so

Other members like TitanMike are a real good source too

OK, thanks for this info.