How do the single charge / discharge BMS's work ?

Batteries, Chargers, and Battery Management Systems.
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Waynemarlow   1 kW

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How do the single charge / discharge BMS's work ?

Post by Waynemarlow » Jan 12 2017 12:41pm

We all use light packs that have a single charge / discharge connector, how do they work as effectively in my view there wouldn't be a max discharge current protection.

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amberwolf   100 GW

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Re: How do the single charge / discharge BMS's work ?

Post by amberwolf » Jan 12 2017 2:25pm

What do you mean, exactly?

Do you mean a BMS that uses the same port for charge that it uses for discharge?

If so, they are generally exactly the same as BMS that uses separate ports, except that both negative wires have been connected together. Often enough they are actually the very same board, but there are probably some that are made specifically for combined port use and don't have separate pads on the board for charge and discharge.

So whatever protections they have for one, are also there for the other.


I used to have a pack that had a BMS with separate pads on the board, but it was wired from the pack maker to use a single connector to the outside world for both. I used it that way for a while, but eventually disconnected their internal wire connection between them, and wired them out separately, for convenience in leaving the pack connected to my controller all the time (via a breaker-switch) and a separate charge plug. Worked the same either way, except for that.

James Broadhurst   10 W

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Re: How do the single charge / discharge BMS's work ?

Post by James Broadhurst » Jan 12 2017 3:55pm

Modern BMS have a single pair for charging and discharging. They're bi-directional. I don't know how it's done but bidirectional interfaces aren't unusual. The HCX-D167 from BesTech is an example of a 10S
http://www.lithiumbms.com/37v10spcmbmsp ... -D167.html
and there's an EBay example of a dual pair here
http://www.ebay.co.uk/itm/262605636328

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