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ipman avatar image
ipman asked

Battery Balancer with BMV 712 on 48 VDC battery bank

In June '22, I bought 3 Battery balancers and a BMV 712. It seems the drawing, which came in the box, for 48 VDC, 3 parallel packs (each 4×12 V 115 AH), are not right. Victron BB.jpg I connected it as shown. After first switch on, some lights were on and from the balancer at the right (BB3) some smoke came out. I switched off immediately and checked the connections. I thought it was wrong and swapped the battery wire, Balancer 1 and 3. At Power on, all three green LEDs lighten up. The BMV 712 was working too, and over time the balancing percentage dropped to almost zero.

When I checked my Battery bank last week, Jan '23, I experienced some weird measurement. The voltage was very different, all three Batteries which connected to minus-bus bar had 15 VDC, the 9 others had around 13.32–13.67 VDC. This is happened awhile after the charging is finished and switched to floating voltage 55.2 VDC. I found online the drawing on Victron HP Victron BB2.jpg, so I installed the missing minus link. At Power on, the Green LED and Orange (high voltage upper battery) on BB1 (left) lightens and Green LED and Orange (High Voltage lower Battery) on BB3 (right) lighten up. At the BB2 (middle), all LEDs are off.

Has somebody an explanation for it? What did I wrong?

Just opened the case from the smoking BB3. The IC2 has a hot marker, but it seems it is just the enamel which smoked. I swapped the Position BB2 with BB3 already.


Thank you for any idea.

Battery Balancer
victron-bb.jpg (713.7 KiB)
victron-bb2.jpg (709.4 KiB)
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4 Answers
kevgermany avatar image
kevgermany answered ·

Did you follow the English or German wiring diagram?

There's a wire not shown on the English version between the middle and bottom strings on the right.

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Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @Ipman

We're sorry to hear about your experience with the Battery Balancer, particularly the erroneous diagram that led to the problem. Clearly our fault. The problem has been identified and Victron is making sure that new battery balancers are shipped with correct instructions.

Meanwhile check out the datasheet from the product page, which has the updated instructions.

If there are still problems with one the Battery Balancers, please contact your dealer so that the device can be replaced.

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ipman avatar image
ipman answered ·

Exactly, I followed this wrong drawing in the first place, but correct it now, connect the missing wire.

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ipman avatar image
ipman answered ·

Hi Stefanie,

thank you for the feedback. It seems the system is working as it should after the modification, the imbalance is down now from 2.8% to 0.9. I hope it will be better in few days or so.

I contacted Offgridtec already to replace the one which smoked a little just in case. It seems he is working, but he will fail in the future at first, maybe. Thanks for your support.

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That's good indeed, thanks for letting us know and for bringing the issue to our attention!

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