How much power can I pull from my lithium battery before BMS kicks in or things blow up?

[NeedForSpeed]

I've scoured the web but have yet to find an answer to my question, how much power can I pump out of a battery (i.e. via a high amp controller) before the BMS kicks in? In other words, how big of a controller (amps) can I use without everything shutting down (or blowing up).

Currently I have a 72v lithium ion battery with the following specs:
- Continuous Discharge Current: 50Amp
- Peak/Max Discharge Current: 150Amp
- BMS discharge current: 40amp
(https://www.aliexpress.com/item/Best-quality-72v-20ah-triangle-battery-72v-ebike-batterie-72v-3000w-li-ion-battery-pack-for/32752508454.html?spm=a2g0s.9042311.0.0.TGuZIB)

And a 40A Sinweave Grinfineon Controller (from Grin tech) with the following specs:
- Battery current: 40a
- Phase Current Limit: 120a
- 12 x 4110 FETS and 100V capacitors
(http://www.ebikes.ca/shop/electric-bicycle-parts/controllers/c7240-gr.html)
(http://www.ebikes.ca/documents/Grinfineon_V2.1.pdf)

And a Crystalyte TC100 motor, a CA3, all on a heavy EEB frame + dual crown fork + not light tires (eg think stealth B-52 which was my inspiration)

Everything works well right now, but the torque is anything but exciting, and I'd like to improve on that, which leads me to think about getting a higher amp controller (side note, I did a minor shunt mod which helped a bit, but I don't like that I don't know what the actual current is, and I don't want to push it much further and fry the controller).

My main confusion is between these two numbers of the battery:
- Peak/Max Discharge Current: 150Amp
- BMS discharge current: 40amp

So I'm assuming I can pump out 150Amps, but for how long? 10 seconds? 1 minute? I have no understanding of that value. And how does that relate to the BMS discharge current? When will my battery call it quits if I'm trying to draw too much power from it?

I've been looking at this Kelly (programmable) controller:
•Peak Phase Current, 10 seconds: 220A.
•Continuous Phase Current Limit: 85A.
(http://kellycontroller.com/keb72450x24v-72v220a45kwe-bike-brushless-controller-p-275.html)

Can I get away with this? Will my battery really be able to handle 220A, or am I wasting my money?

For additional context, I mainly ride for my work commute in Boston city streets, I don't really care about going more than 35mpg, I just want some wicked torque at stop lights for like 5-10 seconds, and I'm fine cruising afterwards at like 30-35mph.

Can anyone clarify these numbers in terms of what my battery can handle? And any recommendations on a new controller to give me the boost I'm looking for? Or should I just mod the shunt even further? And have a backup controller if I fry it?

For anyone curious, I've attached my shunt mod, note, I only added solder to the left leg of the bottom shunt, the top already looked like that when I opened it. If anyone wants to guess what the amps would be at just from looking at it, I'd be curious. I was being very conservative with the first mod.


An old WIP pic of the bike:

 

[wesnewell]

Specs on your battery pack say it uses 3C cells, so it's rated for 20x3 continuous, or 60A. States 150A peak discharge, but it doesn't say if that's peak for the battery pack or the bms, so your guess is as good as mine. I wouldn't want to draw more than 60A max from it though. If you're looking for high current draw, you need more than 3C rated cells.

 

[footbaldd]

You are probably getting a lot of voltage sag on that pack under load. I am building a similar build, but with 21s12p LG HG2 cells (20a continuous rated, but I shouldn't see past 14a and mostly below 10a) , Bestech 160a BMS, TC4080 motor, and the ASI BAC2000 drive. I would definitely not want my battery to be the limiting factor in the build.