Hack Greentime BMS for more then 30A?

[markz]

Is there a way to hack them to get more then 30A?
Shunt mod on a 45A probably doing 55-60A.


https://www.aliexpress.com/store/product/13-lithium-battery-protection-board-48v-lithium-battery-BMS-30A-continuous-60A-peak-discharge/313864_1741121963.html?spm=2114.12010612.8148356.6.110418cctAELEQ

https://www.aliexpress.com/store/product/14S-lithium-battery-protection-board-48v-lithium-battery-pack-BMS-30A-continuous-60A-peak-Discharge/313864_1741119929.html?spm=2114.12010612.8148356.2.110418cctAELEQ

 

[amberwolf]

There's always a way.

Whether it's worth it to you or not...that depends.

Maybe start here:
https://endless-sphere.com/forums/viewtopic.php?f=14&t=95853
for general principles?

 

[markz]

.

Looking at the lineup of cell balancers from Best Tech Power, the pcb design is simple as can be. The backside is all empty, and the populated side are a few full watt resistors and a couple tiny ic's. Be cool to get some laptop chargers that just go up to say 18V instead of 21V then just leave them at 18V to balance out.


It got me thinking that buying one of them could be high on the list of purchases for my new LiMn battery pack of 25R's. Then I dont have to pay for an expensive, high discharge BMS. Just charge it up and let sit to balance out, depending on the balancing current in the specification.

Of course, there is the obvious choice of just using them RC Balancer Chargers, anything from the cheap $20 to the $400 iChargers.

Its always a dilemma isnt it, for us in the ebike game. Cheap the fuckout when you first get into it, buy the cheap $20 chargers and wait an entire half a day. I remember pulling that move. Step it up to a hunny or two ($) iCharger, like icecube57 had a couple nice pups there with his side biz.

Best Tech Power is expensive, I emailed them on prices for 40A-80A BMS units, I know they used to be a minimum order quantity of 2, but you know they'd be top quality compared to a fleabay wonder product.

 

[markz]

Cell Balancer, 3 power resistors, 2 smt resistors, 1 cap, Q1, Q2, U?. Hook up to a "bus" neg and pos. Starts moving pixies around! Say $0.80 per 1S1P having 10 or 14S, and 4P, $55 total.
http://bestechpower.com/balanceboard/HCX-D162.html


Well time to do some research on how they operate. They seem so simple!




https://youtu.be/wIbHLacozFo?t=362


https://youtu.be/TK7re9y_Pxs?t=23

 

[amberwolf]

Cell balancers are completely different than BMS, and different from the topic / title idea, so not sure what exactly you are after.

Do you want just balancers at 30A balancing per cell, for a huge pack that charges very fast?

Or do you want a BMS that can support more than 30A discharge? (which is what the first post sounded like)

FWIW, the balancers do not replace a BMS, they just balance cells.

A BMS does more--it senses LVC and HVC and shuts off discharge and charge (or sends a signal to something else that does that, lke a contactor, etc).

Be cool to get some laptop chargers that just go up to say 18V instead of 21V then just leave them at 18V to balance out.

:? Unless the balancers are programmable or otehrwise alterable for a lower balancing voltage, you won't get any balancing at all at 18v, assuming a 5s pack (which 21v / 4.2v per cell equals out to).

Then I dont have to pay for an expensive, high discharge BMS.

YOu don't have to do taht anyway. See the thread linked previously for some examples on modding cheaper ones.