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Serial vs parallel
#1
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Hello,  I am trying to understand the prevalent pack configuration where batteries are assembled in parallel and then in series to get to the desired voltage. 
Once you have, say, 14 packs (for 48-52v) strung together, you cannot expand the assembly, by adding another pack in the string, without increasing the voltage.

It makes more sense to me to have modular packs of 14 batteries in series, and then string them together in parallel.  If you get more batteries, you can build additional 
packs and add them without increasing the voltage. If a pack in the middle goes south, it can be pulled, repaired, and put back in service.

I built a 2kw system 7s40p 24V solar generator like this as a proof of concept.  The batteries are in 3/4" PVC pipe and have a fuse link (35awg 5A wire) between each battery.
The inverter is a re-purposed 24V APC UPS.
 
So, what are the pros and cons of serial first, then parallel over parallel first, then serial??

My next project is a 14S114P setup (about 12.2 KV) in 3x5 plastic battery holders.  (1596 batteries).  
Repackr doesn't accept it as a 14s114p, but works if I reverse it as 114s14p.

BTW,  I have benefited greatly from  receiving monolithic packs of say 100 batteries where there was a single battery in the middle that ruined the pack.
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#2
1 bms or multiple bms. Thats basically it. You need 1 bms per string.

But you can always interconnect multiple strings. Thats basically like paralleling first.

All is in FAQ here.
5buBZMKeJZgapTGsbGzKf and davidknowles like this post
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