Low Cost BMS for Home Storage Batteries

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Joined: Mon, 17 Sep 2018, 16:30
Real Name: Francisco

Re: Low Cost BMS for Home Storage Batteries

Post by francisco.shi » Sat, 01 Dec 2018, 07:53

How big are the capacitors?
Do you have a circuit of how the capacitors are switched?

T1 Terry
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Real Name: Terry Covill
Location: Mannum SA

Re: Low Cost BMS for Home Storage Batteries

Post by T1 Terry » Thu, 06 Dec 2018, 11:14

Sorry, been off the air for a while, daughter is in hospital in Canberra with back problems that required surgery.
The units we use are mass produced some where in China and are designed to balance 4 cell groups. We balance cell groups 1 & 2, 3 & 4, 5 & 6, 7 & 8.Seems to working ok, there is the possibility of the 2 series cell groups within each pair to get out of balance slightly with each other, but combined with the charge limit of 3.6v in any one cell group the drift apart is limited to a max of 3.4v low - 3.6v high in the pair and that has never shown up o the extend over a 12mth log of a 600Ah @ 24v off grid system we monitor closely as our test outfit out in the field while I get our system installed and running. I could drop the high charge cut off to 3.5v to bring the two even closer together, but a differential of 0.02v max at the top end of charge is really neither here nor there.

T1 Terry
Green but want to learn

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