Choosing a BMS

[paul2129]

Hi guys, I posted in another part of the forum previously. I'm trying to do a little project to learn battery pack building by modifying a Dyson Cordless battery pack. I'd bought a battery pack from eBay which was sold as dead. I opened it and found one leaked cell. I replaced the cell, but the indicator light on the pack flashes red and the vacuum doesn't operate. I tested the voltage of the (charged) pack after assembly, it was 25v (its 6 cells in series)... I assume the BMS has expired
What I need to know is, how do I find a BMS suitable to take care of these batteries ? I think the motor of the vacuum is rated at 350watts, and there is an additional small motor in the brush head.
Since this is a project that might not work, I just need a basic BMS, I'll later assemble a larger capacity pack with a different configuration of cells. I think I can still use my 6-cell BMS if I parallel them up ?

Many Thanks

 

[paul2129]

I thought this would be an easy question for you guys, does anyone know what spec of bms to buy, or alternatively some website where I might enquire ?

Many Thanks

 

[paul2129]

Does anyone have any ideas ?

 

[dogman dan]

Looks like your cells charge to 4.2v so you need a 6 s bms for li-ion. Not lifepo4.

350w is 14 amps of 25v. So look for a bms rated for at least 20 amps continuous, so it does not pop every time you start the thing.

Look for 6s 20 amps bms.

 

[paul2129]

Thank you very much for your reply, it's pretty much as I'd thought, is there any particular recommendation for somewhere to buy one, or just a general search online ?

Thanks

 

[cal3thousand]

Thank you very much for your reply, it's pretty much as I'd thought, is there any particular recommendation for somewhere to buy one, or just a general search online ?

Thanks

Bestech is a popular brand on here and you can find them on eBay and Alibaba