question

hkettler avatar image

Parallel wiring of Lifepo Batteries

I would like to install 3 of the new 200Ah Lifepo batteries in a parallel setup. The Documentation asks to have each string fused per battery. Usually i would go for simply interconnecting the batteries with well dimensioned short length cables and have one fuse for the complete battery bank. The simple way would save me space, save transition resistance, less failure points etc.

Is there any special reason to have each battery fused individually or is it "just" the way of the very lowest risk.


Any advise is appreciated :-)


EDIT: @Margreet Leeftink (Victron Energy Staff) Four posts later your awesome handbook got posted. Maybe you might pick up my question in this in any future release. ;-)


Lithium Batteryparallelfuse
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3 Answers
Daniël Boekel (Victron Energy Staff) avatar image

Hi @hkettler

Q: Is there any special reason to have each battery fused individually or is it "just" the way of the very lowest risk.

A: yes, when one battery in a string has a problem, it will be protected by the string fuse (so the other batteries won't discharge full power into this string).
Also, the string fuses prevent overload on one of the strings, while a fuse for the complete set wouldn't protect a single string.


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Gary Pacey avatar image

@hkettler In the case of mobile applications where the batteries are adjacent to each other, our opinion is that individual fusing is most likely a liability. The additional components, terminals and wire lengths all introduce potential failure points and resistive imbalance.

We would recommend the traditional short cable interconnection between the batteries with positive and negative connections at opposite ends. The reason being is that the Victron lithium batteries (like lead acid) are not going to fail in a short circuit mode so there is no point in individual battery fusing.

Be sure that all cables are appropriately sized and place a single fuse close to the battery bank in the positive cable.

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kai avatar image

I believe there's a couple of threads on this forum on this particular topic. Fuse for each string provides incrementally more protection. Whether that increment is worth it to you compared with the associated downsides is your judgement call

edit: let me add a disclaimer since you're referencing a Victron document. I'm not a Victron rep and whether they would see a single fuse as violating the install specifications I'm not going to speculate

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