JK BMS in parallel

can someone explain why JK BMS cannot be paralleled with another set of 16s with jk bms? I was also informed by supplier to use T-fuse instead? I just do not get why it will not work?

chasoy said:

can someone explain why JK BMS cannot be paralleled with another set of 16s with jk bms? I was also informed by supplier to use T-fuse instead? I just do not get why it will not work?View attachment 122084

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I have six in parallel, working just fine. Those are in parallel with a JBD, two Overkills and a Seplos.

I hope the supplier is trying to say not to parallel two BMSs on one battery to get twice the amps. Many of us have BMSs in parallel just like your diagram. I have two overkills in parallel, which are rebranded JBD BMSs.

For the class T fuses, I have a 125 amp fuse at each battery, and then a 225 amp class T fuse after combined.

I have 6 JKBMS' in Parallel without any issues and YES, each Battery Pack is fused with MRBF Fuses (I am 24V so that's fine) for 48V you need to step up to T fuses and others rated for 48V+.

Not trying to hijack the thread, but I've seen Andy from the OffGrid garage YouTube channel using Noark breakers and no class T fuses at each battery bank. Any reason why would that not be suitable?
Cheers.

tonyg said:

Not trying to hijack the thread, but I've seen Andy from the OffGrid garage YouTube channel using Noark breakers and no class T fuses at each battery bank. Any reason why would that not be suitable?
Cheers.

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Yes, you can use Quality Breakers instead of fuses at each BATTERY PACK within a Bank of batteries.
A Bank is a collection of complete batteries (Cells & BMS) running in Parallel. His current 3 Pack Bank uses 1 Breaker per Pack and one Master Breaker to "rule them all" ;-)

The REAL TRICK is to find DC Breakers capable of handling the large gauge wires and pending where you are, that may be difficult and pending on the layup may even be very awkward.

This issue was widely debated last year in a post that I started. It turns out that the issue that the JK engineers were afraid of was the cross rush of current that would occur if two batteries were connected together with a large difference in voltage which would damage the FETs. The class-T fast acting fuse diagram was produced by one of our members to show how that large inrush could be cut off with the addition of the fuse.

hwse said:

The class-T fast acting fuse diagram was produced by one of our members to show how that large inrush could be cut off with the addition of the fuse.

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I don't believe any fuse or indeed breaker that can carry the rated current is going to break fast enough to protect the BMS in this situation.

Quattrohead said:

I don't believe any fuse or indeed breaker that can carry the rated current is going to break fast enough to protect the BMS in this situation.

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You need to remember that the JK is rated to take a surge current of 350A for up to 300-seconds and millisecond bursts at currents than that. This will give a properly sized fast acting fuse sufficient time to bread the connection so that the FETs do not need to. In Andy's first video on the 4s JK, he smoked a FET. It turns out that this happened after he had been discharging at 241A for 5 full minutes (300-seconds) when the then very hot FETs were forced to call it quits. This caused one of them to lose its magic smoke. In spite of this clear abuse, the BMS still functioned perfectly and as far as I know, he is still using it because it failed OPEN as it should and now it is "limping" along on 19 of its 20 discharge FETs.

Hello from France,
I am new to this forum and I am looking for information about the paralleling of 2 BMS JK_B1A8S20P CAN.
For quite a long time I have been using for my van to set up a 280 Ah battery with a BMS B1A8S20P CAN with a communication module (JKV250) to a Victron Cerbo GX in VE.CAN.
I would like to put a second one in parallel, but I can't find the possibility to change the IDs transmitted on the CAN network.
I don't care about changing the identifiers, it's to put on the same CAN network.

Do you know if there is a solution to change IDs?

Thank you for your help.

Alexis

Bonjour de France,
Je suis nouveau sur ce forum et je suis à la recherche d'informations concernant la mise en parallèle de 2 BMS JK_B1A8S20P CAN.

Ça fait assez longtemps que j'utilise pour mon van aménager une batterie de 280 Ah avec un BMS B1A8S20P CAN avec un module (JKV250) de communication vers un Victron Cerbo GX en VE.CAN.
Je voudrais en mettre un deuxième en parallèle, mais je ne trouve pas la possibilité de modifier les ID transmis sur le réseau CAN.
Peux m'importe la modification des identifiants, c'est pour mettre sur le même réseau CAN.

Savez-vous s'il existe une solution pour modifier les ID ?

Merci pour votre aide.

Alexis