Keep an eye on the BMS.

[dogman dan]

Very good point. How much for just the bms? A few of us have fried one from ping or Anna. Especially those with 2 batteries going for 72 volts.

 

[GGoodrum]

While I would agree that a BMS definitely needs over-discharge protection, at the cell level, and you do also need some sort of charger control/balancing capability, I disagree, however, that you need to have the BMS do any sort of current limiting, or over-discharge protection. Current protection doesn't have to be done at the cell level, as all the current has to go through all the cells. The controllers already limit ihe current and to protect against a dead short, a fuse can be used. Why complicate the BMS with "extra" circuitry it doesn't need? You could get rid of most of those "expensive" FETS that are being used for over-current protection.

I do like how your cells are packaged, however. This is a ton better than the flimsy tab connections being used on the so called "duct tape" packs that Ping sells. For this reason, I think your packs are definitely worth more money, but not because your BMS board is more expensive to make.

-- Gary

 

[fechter]

See, they read our PIC based battery managment system thread and actually made one. :wink:

What processor type does it use?

All of the above listed features are desirable. For e-bike or scooter application, overcurrent and undervoltage protection can be implemented by interfacing the BMS to the brake input on the controller, eliminating the need for large transistors on the BMS. For universal application, the BMS based limiter is nice.

 

[dogman dan]

I thought the same thing, so how much for one without the battery?