I have recently purchased a BMS rated for 3S, 40A (still in transit). Following is pictures for this BMS:

3s 40A BMS

Now, according to seller, this has over-current, over-voltage, under-voltage and short-circuit protection and 100mA balancer.

Now, After closely looking at the pictures, I couldn't find current-sense resistors on these pictures, so I am not sure how this module can provide over-current protection.

My question is: Does the pictured BMS have a current-sensor of some kind, or does it have any kind of over-current protection?

  • 2
    \$\begingroup\$ Please link a data sheet for the device. I mean... you bought it on the basis of what the data sheet said, yes? \$\endgroup\$
    – Andy aka
    Commented Oct 28, 2020 at 14:24
  • 1
    \$\begingroup\$ the big 43R series resistors ? \$\endgroup\$ Commented Oct 28, 2020 at 14:24
  • 3
    \$\begingroup\$ @TirdadSadriNejad no.. 43R are balance discharge resistors. I am fairly certain of that \$\endgroup\$
    – GPS
    Commented Oct 28, 2020 at 14:26
  • \$\begingroup\$ @Andyaka I don't have a datasheet. I did buy based on seller's description. I don't expect seller to be able to answer any technical questions \$\endgroup\$
    – GPS
    Commented Oct 28, 2020 at 14:28
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    \$\begingroup\$ I’m voting to close this question because this is about a product without documentation fulfilling specifications that only the designer / seller can guarantee. You need to ask them – us figuring something out won't help you anyway. Generally, no datasheet, no sale is a good strategy, and the only person responsible for what you bought implementing what they promised is the seller. \$\endgroup\$ Commented Oct 28, 2020 at 14:53

1 Answer 1


As it turns out, there are very similar looking BMS where some have current limiter but others don't, and then others that don't have balancer etc.

Product description of one was lingering in my head, while I had bought another different product, hence the confusion. Seller wasn't much help.. he doesn't know whats what, just that I'll get exactly whats pictured (which I did).

The current limiting ones do have two parallel R005 on B- connection in their pictures.


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