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Charge AND balance 4 Lipo packs? Series Parallel solution help. Answered

I have x4 identical Turnigy Graphene Professional 5200mAh 3S2P 15C LiPo Packs w/XT60 - and I need 22.2v out of them for a portable boombox project.
  I have x2 12S 30A BMS's to balance / charge on board and a 600w 48v 12.5 A power supply.
By wiring up the battery packs in series then parallel to get the 22.2v output - if I then connected the BMS (either by directly wiring to each cell or using the pack balance plugs) would it would cause a short circuit through the balance wires? 
  The ideal solution would be a wall plug power supply that plugs into the (sealed) boombox and charges all of the batteries through the BMS's. Is there any way of achieving this through parallel charging (not a fan) or could I switch easily between the two wiring set ups?
  I'm trying to avoid buying a £200 Lipo charger and connect the batteries directly or keep disassembling the boombox every time it needs charging.


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4 years ago

In answer to my own question!

The way to solve this is to have a 'patch panel' on the box that has the connections from the balance leads and the main charge/power leads (power leads run through a 3 way switch (gives option to isolate batteries) on the back of the boombox so it's either batteries connected to the load or the off-board BMS charging system).

When charging, the patch panel pin-out plugs match x2 small 3S parallel charging boards connected to the BMS and power supply. As long as I remember that the balance wire terminals on the patch panel are always live and put a rubber flap over them when not in use, I think that'll work!

Now I've 'just' got to work out how to include the 12W solar panel charger with a float circuit so that I can trickle charge at 2A on sunny picnics whilst listening to ma tunes!

Then make this into in Instructable of course.