How to trigger BMS overcurrent?

[E-HP]

My new battery was delivered yesterday. UPP 14S8P, 52V 28Ah, 40A BMS, Samsung 35E. I want to make sure that the BMS is rated at 40A, since UPP offered a 30A version as well, and I traded emails with the vendor about it. I'm concerned, since the vendor said they could ship a 30A version faster from their US warehouse, but the 40A would come from the factory in China. Well the battery showed up way early, so I'm a little suspicious.

My old battery has a 30A BMS, but I've never had it shutdown due to over current. Even drawing over 40A for 10 or 15 seconds at a time, so I'm not sure what it takes to trigger the BMS to shutdown. It will, however, shut down if I peg the throttle, without controlling the ramp with my Cycle Analyst, but I haven't figured out if that's due to overcurrent or not (maybe it's short circuit protection kicking in).

The new battery is charging now, but once it's done, I want to figure out how I can test the BMS without opening up the battery, just to make sure I got what I ordered. If there's a reliable way of doing it, I'd first test my existing battery, then see how the new one performs under the same conditions.

 

[john61ct]

Overcurrent and short-circuit protection are usuay the same on inexpensive gear.

Does your equipment display motor amps while riding?

 

[E-HP]

Overcurrent and short-circuit protection are usuay the same on inexpensive gear.

Does your equipment display motor amps while riding?

Nope, only battery amps with the CA. I guess my first test then will be to try my throttle in bypass mode to see if the BMS trips under full throttle.

 

[john61ct]

add heavier weights, go up steeper hills?

Watch the CA to see around what battery ampacity it's actually cutting out

 

[E-HP]

add heavier weights, go up steeper hills?

Watch the CA to see around what battery ampacity it's actually cutting out

That's the problem, it will trigger even before the display catches up to show the reading. I tried rolling on the throttle a little slower and can get the bike to wheelie and the display will show something over 30A, but any faster and the BMS trips before the display updates. But, I just thought of something. I didn't check to see if the CA recorded the Max Amps in those cases, so maybe that will reveal something.

 

[qwerkus]

My new battery was delivered yesterday. UPP 14S8P, 52V 28Ah, 40A BMS, Samsung 35E. I want to make sure that the BMS is rated at 40A, since UPP offered a 30A version as well, and I traded emails with the vendor about it. I'm concerned, since the vendor said they could ship a 30A version faster from their US warehouse, but the 40A would come from the factory in China. Well the battery showed up way early, so I'm a little suspicious.

My old battery has a 30A BMS, but I've never had it shutdown due to over current. Even drawing over 40A for 10 or 15 seconds at a time, so I'm not sure what it takes to trigger the BMS to shutdown. It will, however, shut down if I peg the throttle, without controlling the ramp with my Cycle Analyst, but I haven't figured out if that's due to overcurrent or not (maybe it's short circuit protection kicking in).

The new battery is charging now, but once it's done, I want to figure out how I can test the BMS without opening up the battery, just to make sure I got what I ordered. If there's a reliable way of doing it, I'd first test my existing battery, then see how the new one performs under the same conditions.

Please do open it - especially such a large pack. I got a few upp batteries for clients, and most came with serious shortcomings. The bms they use are cheap but usually work ok; main problem is that they tend to use only a flimsy 0.15*7mm nickel strip on both battery poles, which can handle 5-10A, but nowhere near the 30A rating of the bms.
Standart modus operandi now whenever I get my hands on upp packs is open it, solder a copper bus bar as collector on both poles and change the bms. Than add a layer of capton and re-shrinkwrap.
If you want to get better bms, I recommand Annpower or jbd on alibaba or aliexpress. Not super quality, but way better than most cheap bms I've seen.

 

[E-HP]

Please do open it - especially such a large pack. I got a few upp batteries for clients, and most came with serious shortcomings. The bms they use are cheap but usually work ok; main problem is that they tend to use only a flimsy 0.15*7mm nickel strip on both battery poles, which can handle 5-10A, but nowhere near the 30A rating of the bms.
Standart modus operanding now whenever I get my hands on upp packs is open it, solder a copper bus bar as collector on both poles and change the bms. Than add a layer of capton and re-shrinkwrap.
If you want to get better bms, I recommand Annpower or jbd on alibaba or aliexpress. Not super quality, but way better than most cheap bms I've seen.

Thanks, good tips. I was going to switch to a bluetooth BMS if this one didn't turn out to be 40A. I'll see how it performs after it's charged up. 28Ah takes a long time at 4A

 

[E-HP]

After setting the CA to a limit of 40A, and setting my throttle ramp from 19 v/sec to 25 v/sec, it feels just right, with the bike doing a small wheelie for about 15 feet, with the front hovering about an inch off the ground; With my old battery, the BMS would trip. The bike feels really good at 40A, but the CA seems to use that as a hard limit, so even if the battery can provide 90A peak, the CA limits to 40A. So, I set it to 60A, which is 50% more fun :lol:

Then I after riding around for a while, I found a paved path with a 22% grade for a little over 1/4 mile, which seemed to be a good test. I pedaled, since I really wouldn't want to have the BMS trip while on that steep a hill, but I figured my 150W or leg power isn't enough to make a difference. With pedaling, I was pegged at around 51A, but the motor wouldn't pull any more. I'm concluding that it is a 40A BMS.