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2 Batteries in parallel?

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(@skokie)
Posts: 49
Trusted Member Customer
Topic starter
 

Is it possible and does it make sense to install a system with 2 LiFePO4 Batteries in parallel to have the possibility to cut one Batt from that system if something failed? the system should run with the remaining cellpack independently. 
My Idea is an active backup system. Two batteries, using the same charging peripherie. Automatic or manual on/off of a single Batterypack. Both Batteries are normally working together in this set up. If any electrical problem might appear, the failed battery will be cut off. 
The problem seams to be the identical voltage and SOC when coupling the batts again after a certain time off separation. 

Is there a system schematic available? Any thoughts or pros&cons to discuss? Experiences?  All opinions are welcome.

Thx 

Jens

 

 
Posted : 31/12/2023 11:08 am
(@philtao)
Posts: 348
Member Admin
 

Hi Jens,

I have summarized here the potential issues when connecting two or more drop-in batteries in parallel.  Some of these issues might be reduced when using a performant BMS 😉

In any case you will need one BMS for each battery and wire the outputs either in series or parallel to create AND / OR functions.  For the Can bus commands one of the BMS is set as the master and performs computations to send on the CAN bus the combined commands. It requires a bit of planning but it is doable.  🦊 😸 has recently done it on his boat with two 700 Ah batteries... Last news is that all was fine and behaving as expected.

 

 
Posted : 31/12/2023 11:04 pm
(@skokie)
Posts: 49
Trusted Member Customer
Topic starter
 

Hello Philipe, happy new year!

thanks for your quick return to my question on your high expert level. It shows, that the target to get a more safe system with a double (split) battery has to be payed with a more complex installation, which is at least raising the risk of failures.

cheers  Jens

 
Posted : 01/01/2024 5:55 pm
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