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So in general, would it be ok to use two of the same 3S BMS circuits in parallel on the same stack of batteries? I don't have an even number of parallel cells for my project (3S5P), but each BMS is only rated for 10A and I want to make sure I'm well within limits on these circuits. If I put two in parallel would that be likely to completely bork or be totally ok? Has anyone tried this before?
Two BMS in parallel on the same batteries?
- Thread starter LikeTheSandwich
- Start date
I believe you. But I'm curious, do you know why exactly it's a bad idea?
Sounds like I should mock it up with a bench power supply and some multimeter to test and see what happens if the results are unknown.
Lithium based Cells can be very dangerous.
You will still not know what may happen after extended, and unattended, operation.
I recommend that You do not even attempt testing,
I'm quite sure that You don't have the proper equipment, nor the experience,
necessary to make a judgement call on such a hazardous endeavor.
You are playing around with the possibility of a serious FIRE.
Get a single BMS with adequate Specifications.
.
.
.
You will still not know what may happen after extended, and unattended, operation.
I recommend that You do not even attempt testing,
I'm quite sure that You don't have the proper equipment, nor the experience,
necessary to make a judgement call on such a hazardous endeavor.
You are playing around with the possibility of a serious FIRE.
Get a single BMS with adequate Specifications.
.
.
.
You might be right. But you also might be wrong. If you don't even know what will happen, I don't see how you'd be in a position to make accurate assumptions about what equipment or experience I might have. In any event, I can still mock it up with a power supply and do some testing. It's worth trying for the experience, as my power supply has multiple overcurrent fail safes so even in the event of a catastrophic failure those safeties (including fuses) should kick in and keep everything safe. If you'd like to learn what happens, I can share my results afterwards.
"" ........... If you don't even know what will happen, ........... ""
Nobody "knows" what will happen,
But I have almost ~60-years of playing with Electronics that tells me
that You're just asking for trouble.
I have a good idea what your equipment and experience is like
based on the fact that You see zero problem with what You are thinking about attempting,
and the fact that You have to ask any questions about doing it in the first place,
and the fact that a ~$10.oo BMS-Board is just too much trouble and expense for You.
I've been where You are at least a thousand times,
and I'm lucky to still be alive,
in spite of all my previous ignorant decisions.
You asked for an opinion, and You got my best advice.
You can certainly take it or leave it, as You choose,
but You won't ever get my agreement for what You propose to do.
It's just not a good idea.
I hope You don't burn-down your house.
.
.
.
Nobody "knows" what will happen,
But I have almost ~60-years of playing with Electronics that tells me
that You're just asking for trouble.
I have a good idea what your equipment and experience is like
based on the fact that You see zero problem with what You are thinking about attempting,
and the fact that You have to ask any questions about doing it in the first place,
and the fact that a ~$10.oo BMS-Board is just too much trouble and expense for You.
I've been where You are at least a thousand times,
and I'm lucky to still be alive,
in spite of all my previous ignorant decisions.
You asked for an opinion, and You got my best advice.
You can certainly take it or leave it, as You choose,
but You won't ever get my agreement for what You propose to do.
It's just not a good idea.
I hope You don't burn-down your house.
.
.
.
I am curious to know if you tested it yourself. I am running two x 200A JK BMS in parallel on one 840Ah life battery for almost two years now and it runs like an experienced couple on the dancefloor. Could not be better. There are videos on YT showing the same.
People also said you cannot mix life and lead batteries but I am running life and lead batteries in parallel for more than five years now. It is the same life battery with the parallel BMS system. Also there are many people doing it for much longer than I am and lots of YT videos and write ups about it.
No problem at all.
I just want to expand a bit on bms units in parallel. A bms is basically a on/off switch working on command settings. It is working on the "if - then" decisions. If the voltage or current is to high or to low as per settings, switch off. If back to a certain reading, switch on again. It also have a cell balancing circuit built in working on its own. All the bms "sees" is voltage and current in and act on that, nothing else.
