Looking for a cheap active balancer/Battery equalizer for lithium ion cells (3.7v)

Idiwzr

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Mar 5, 2019
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Hello guys, I was looking for a cheap active balancer for my diy 18650 power wall I'm working on. Is a small system around 4kw and 7s (29.4v). Most cheap balancers I found only start balancing at 4.18 - 4.2v and I prefer not to fully charge my cells. I'll like them to be around 80 - 90% state of charged. I'm using a 40A 7S BMS, it works well for my application but the balancing current is too low (100ma) and it only starts balancing when fully charged. I'm looking for an active balancer than can balance the cells at any voltage.
I found this on AliExpress "DYKB 3S 4S 6S 7S 13S 16S Li-ion Lipo Lifepo4 Lithium Battery Active Equalizer Balancer Energy Transfer Board BMS 1.2A Balance"
https://s.click.aliexpress.com/e/cBCKX7oc please does anyone ever use it? I want to know if it actually works as advertised.
Thank you
 
You dont get any decent for that price though. Yes it kind of works. Active balancers start at around 15USD per cell and upwards.

BUT thats only the balancer! Do you have that uneven packs that you need to balance with that high current all the time? Isnt it better to arrange your packs and build them properly from start? I have a 100kWh powerwall and I could easily do with 100mA balance current to keep it in balance. Also I use passive balancer. I think i calculated that I needed atleast 10 years of use before I even could save any money going active.

Balancer is nice to have but you need to look at 2 other factors first!

Protection - Without protection no balancer in the world can save you when and if something happens...
Reporting tool - If you dont get notified whats going on how would you be able to tell something is screwed? A balancer that just balance without reporting how much it balance wont tell you if you have a problem unless they cant keep up with it and at that point its allready to late isnt it? :)
You also want to know the status of the packs.


So back on track. Active balancing is awesome for sure and you can save some energy doing it but it hurts your pocket some more initially. The 1s active balancers by deligreen is a well used system and I have done videos about them too.


Another topic can be to look at my passive vs active video



Neither less dont forget protection!
 
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