Hello I have 24 V battery bank on the catamaran. Serial pairs of 12V Victron Telecom batteries connected in parallel (4 pairs). Last year one cell in one battery failed. It became 10 V battery instead of 12V. And all current form working pairs went to this defective 22V pair trying to charge it. W…

[image] ADesign: I am replacing batteries now and want to install extra equipment to achieve two goals: Need alarm for individual cell failure High current prevention between working batteries pairs and failed one. Per cell monitoring wont happen if you use 12v batteries. However you cou…

For sure I will look at MRBF. What will be proper Ampere rating for those fuses, if you can suggest formula? My bank is 4 x (2 x 165Ah 12V) = 660Ah 24V

Yes, just a poorly designed system as far as safety is concerned, but maybe not entirely their fault as the drawing assumes a 24v battery not 2x 12v in series How big is your inverter? That drawing calls for a 400a fuse to the battery bank and your original drawing shows a pair of 400a fuses (poten…

24V 12V Factory A3.pdf (68.1 KB) Here is original factory diagram, you can see two 24V batteries in each hull. In reality was delivered with two pairs of 12V+12V in one hull and two same pairs in other hull. As you can see, no protection by design between two hulls. And yes, 400A x2 fuses are too b…

Also, I need opinions about fuses Many suggest MRBF Fuses, but I will need to have some kind of switch in line with them, to be able to disconnect broken pair of batteries. I was thinking MRCB Circuit Breakers, which can do both, protection and manual disconnect So, question is: MRBF fuses plus …

Ok that is making a lot more sense why they have 400a fuses there, that’s the busbar feeder not direct to inverter. Although the wire size is smaller than I would personally use on a 400a circuit, that in itself is ok as your devices beyond the busbar are fused or breaker’d appropriately (for the o…

I also had problems with a similar configuration on a sailing boat with Telecom batteries connected in parallel (2 pairs). The result was not as dramatic as yours, but with the serial connection one of the batteries always suffers from undervoltage or overvoltage. Despite the balancer. The lifespan …

Yes, I was looking to OPzV, but usually OPzV cells are big. I have limited space in battery compartment, and basically stuck with telecom form factor. Victron has good looking Lithium NG 24V 300Ah, but they will not fit in battery space. Interestingly, you mentioned, balancer did not help, what bra…

Lithium batteries are a different world, but consider that 4 pairs of 12V batteries actually have 48 2V cells connected in serial and parallel, instead of 12 by OPzV in serial with only one fuse! In terms of volume, the 2V cells are 10% smaller than 12V batteries and can be installed in any positio…

If you want a 24 volt system then build or buy 24 volt batteries, especially when using BMS-based batteries. BMS-based batteries put in series will go out of balance. A battery balancer will help, but that just complicates the system.

Interesting. Can OPzV be installed in horizontal position? I do not have vertical space

Need help after 24 V battery bank failure. How to protect from shortcut of one cell in one battery?

DIY

ADesign 14 February 2025 12:37 37

I want to be able to quickly disconnect any of four pairs. Thinking about 4 MRCBs, but many advise me not use them.

And 8 voltmeters to monitor all individual batteries

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Need help after 24 V battery bank failure. How to protect from shortcut of one cell in one battery?

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