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dtcassist avatar image
dtcassist asked

Intermittent use of battery balancer?

I just purchased a Victron battery balancer to correct a voltage imbalance issue I'm having. I have 3 parallel strings of 2x12v batteries. I do not have the midpoints connected, and I don't really want to have to do that.

Only one string has more than an .1v imbalance - 0.4v or so - I suspect I didn't get them fully equalized when installed. My question is, can I use this on an intermittent basis only to correct rather than maintain? I'd like to be able to correct this situation (verify it's not an ongoing battery issue) and remove the balancer, or apply to any string that develops a problem.

Since this balancer is a low current - is there anything stopping me from attaching these with a fused set of jumper clips for a few days as needed? I'd rather not rely on these long term, or have the potential for more issues with an additional installed component.

Battery Balancer
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2 Answers
snoobler avatar image
snoobler answered ·

I don't see any problem with it. Make sure the jumper clips are decent. They're terrible for quality connections and will only inhibit balancing function.


Consider midpoint connection:

https://www.victronenergy.com/upload/documents/Datasheet-Battery-Balancer-EN.pdf

Victron has a wiring diagram for your exact situation.

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dtcassist avatar image dtcassist commented ·

My understanding is mid-point connecting has some cons, like overdrawing multiple batteries in the case of a failure instead of just the one string.


But would mid-point connections also assist in balancing the parallel strings of batteries? Seems to me that my 0.4v difference on one string would have to naturally pull the others to the same - for better or worse?

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snoobler avatar image snoobler dtcassist commented ·

I included the schematic here:


1642566303448.png



Mid point connections "equalize" the error. The 0.1V batteries would be > 0.1V and the 0.4V battery would be < 0.4V.

It would also allow you to use a single balancer to eliminate the discrepancy altogether.

Failures in parallel string config or in the midpoint config are pretty much equally unpleasant.


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1642566303448.png (174.9 KiB)
kevgermany avatar image
kevgermany answered ·

If the batteries are lead based, this imbalance should reduce over time without a balancer. Might never be exactly the same, though, even with a balancer. If the imbalance is always there, check wiring, connections fuses for resistance. Might be a poor battery.

On the midpoint, you have two options, multiple balancers, or joining them.

Also note that the balancer only works when batteries are close to fully charged.

If you have lithium, the self balancing doesn't happen.


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