[chbot] BMS - How they work?

[Charles Manning]

Have a hunt around on youtube.

Basically, the BMS's main jobs are:
* cell protection (over current, over/under voltage). This is achieved by
turning series FETs off to protect the cells from damage.
* cell balancing for series cells. If you're trying to charge a string of
cells then some will get to max voltage before the others. The BMS prevents
those cells from overcharging by providing a bypass path.

Various BMSs have various features (including monitoring etc).


On Wed, Dec 7, 2022 at 12:37 PM Marshland Engineering <
marshland at marshland.co.nz> wrote:

> Aliexpress has many 2 3 and 4 cell BMS boards.
>
> I'm struggling to find out what exactly do they do ?
>
> See here https://www.aliexpress.com/item/33031988423.html
>
> From what I have read, Li-ion batteries have a very specific charging
> method.
> I cant see this board doing anything like this.
>
> I have a 12 Li-ion motorcycle battery with a very similar board in the
> housing.  It uses 4 cells. Does it only charge each cell to 3.6 volts or so
> and not 4.2 ?
>
> From what I think, car and bike batteries use direct connections to the
> cells
> for the high starting currents required but should have a completely
> separate
> charging system. This can easily be done as the alternators can be isolated
> from ground therefore providing a independent charging circuit that can
> monitor each cell.
>
> Something like this.
>
> https://www.aliexpress.com/item/32800729065.html
>
>
> Any thoughts?
>
>
> _______________________________________________
> Chchrobotics mailing list Chchrobotics at lists.ourshack.com
> https://lists.ourshack.com/mailman/listinfo/chchrobotics
> Mail Archives: http://lists.ourshack.com/pipermail/chchrobotics/
> Meetings usually 3rd Monday each month. See http://kiwibots.org for
> venue, directions and dates.
> When replying, please edit your Subject line to reflect new subjects.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ourshack.com/pipermail/chchrobotics/attachments/20221207/22a6f651/attachment.html>