Using generic 72v ebay battery with 80a controlller

[Marskmil]

Hi I have a generic 72v 20ah 50a bms battery from eBay currently using a 72v 50a generic controller and I'd like to upgrade to an 84v 80a generic controller. Can my battery bms handle this do you think? I googled 50a bms and I saw a lot of them peak around 100-150a. What do you guys think

 

[john61ct]

Must be determined by testing.

Actual performance varies widely, not just between models, but can from one production run to the next.

Bypass the BMS wrt power flow on discharge might be best, do you plan to use it for LVC?

 

[dogman dan]

BMS will shut down at or near 50 amps continuous. Not sure how long it will allow a higher spike, but you may get rolling fast enough to avoid it shutting down. Not much point in upgrading your controller till you get a battery that is stronger.

Battery already getting murdered anyway, using it much above 25 amps. Generic cells. Don't you see a lot of voltage sag already? If you have a voltmeter, you are already seeing your battery getting beat to death. You need a CA or other watt meter on your handlebars before you go making changes to up the power you suck from that battery. Its good to know how you are killing your battery, fast or slow. The way you ride will matter a lot.

Charge it outside.

 

[E-HP]

Hi I have a generic 72v 20ah 50a bms battery from eBay currently using a 72v 50a generic controller and I'd like to upgrade to an 84v 80a generic controller. Can my battery bms handle this do you think? I googled 50a bms and I saw a lot of them peak around 100-150a. What do you guys think

Nope. The battery might be good for 40A max, probably 30A continuous. 72V20A of generic cells, usually 2500mAh, would be 8P. Generic cells are good for maybe 5A max, so that's 40A max before you're killing the cells. Save the money on the controller and put it toward a better pack.

 

[skeetab5780]

It really depends on which battery vendor you bought from, if you bought the black shrink wrapped BTR batteries off Ebay then they are Pouch cells and the 50a BMS will handle 150a spikes for 20seconds or so(not that I recommend them since mine was trash) Others have had good success with them recently

But if you bought a generic Ebay 18650 cell pack it will likely barely put of 50a at all

 

[gobi]

it is all about the cells,
do you know what is in it?

Also, how hot does it get when you use it?

 

[Hawaiianr808]

Wait I need some clarification myself now.

I was told this.

If the BMS is at 50amps and the controller is 100amps ita fine because the BMS will just control it. I never heard of over drawing past the BMS and casuing it to be damaged.

 

[E-HP]

Wait I need some clarification myself now.

I was told this.

If the BMS is at 50amps and the controller is 100amps ita fine because the BMS will just control it. I never heard of over drawing past the BMS and casuing it to be damaged.

Nobody on this thread mentioned causing damage to the BMS.

 

[john61ct]

Most BMS do not have any current limiting circuitry at all, they just burn if you go too high.

Best to size the BMS like the wiring or a fuse, 20% higher than the maximum you will ever allow taking peak timing of a few seconds into account as opposed to continuous.

If you really need to go high current, forget about allowing the power to flow through the circuitry, just use the BMS for voltage-based control and use robust external contactors to do the opening cutoff.

Or go without, the term "BMS" is just a collction of functionalities


LVC handled by controller or CAv3

HVC handled by charger

separate controls can act as failsafe if you like

Active balancers for occasional rebalancing