BMS for 13S Battery capable of handling 300A discharge

erenaud

1 µW
Joined
May 1, 2018
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3
Hello everyone,
this is my first post here, I am coming from https://community.openppg.com/ because I would like to build a battery pack with 18650 cells for that flying machine :)

Since this forum is a bit more active around battery building, I thought I'd post here.

The four motors of the OpenPPG will draw 300A peak altogether, so I need a battery pack AND a BMS that can handle this rather high (peak) discharge current.

The LG 18650 HG2 Cell has a constant discharge rate of 20A, so for 48Volts a 13S15P Setup should give me the required 300A

I had a hard time finding a BMS at all, that could handle 300A discharge rate, but this is what I found:

https://aliexpress.com/item/Free-shipping-1pcs-smart-display-3-2V-3-7V-300A-lithium-battery-protection-board-balanced-management/32741659733.html

The seller has sold a few already, and the product has 9 positive and zero negative ratings.
The BMS can handle variable 6S to 14S setups up to 300A constant discharge. It has a display and bluetooth connectivity together with an App.

Sounds all good to me.

Any thoughts from the experts here ?
 
I usually buy from www.bestechpower.com, they are customizable but they require that you buy two :(


Here's an idea or two...

At such high Amps I would go with a small power BMS and a high amp power Braker.

First I would connect the the battery directly to the Controller with the Braker in between. Then hook up a sort of low power relay that switches the ignition wire on the controller when the BMS decides its time to quit. You need the relay because all controllers that I had until now need you to connect the ignition to B+ not B-. PLEASE NOTE IV'E NEVER TRIED THIS :!: :!:

Or you could just not drain the battery all the way, and use the BMS just for balancing and charger cut off. Since new cells shouldn't become unbalanced for a while anyways. You just need to leave your charger plugged in for longer, once in a while to give time for the BMS to balance the cells. << I have done this, no problems so far after two years :)

The reason I'm telling you this, is of course because of the huge price difference. But is of course, less safe!!
 
Every BMS on a vehicle other than an e-bike uses a monitoring system and an electromechanical breaker. Cars, motorcycles and any other large EV doesn't bother with FETs for allowing or disallowing current to flow; it just opens a contactor.
 
@eee291 - I am not sure what exactly you are suggesting, and why you are suggesting it - according to the BMS's description, it is absolutely suitable for what I want to do, it CAN handle the 300A constant discharge - and the price is fine for me, considering that it monitors the whole battery while charging and discharging.

@jonescg - It sounds like you are contradicting what eee291 said, that's fine as I am not sure what he/she said - however the BMS does control the current flow with FETs. I only have very basic electronic knowledge, but what this picture (taken from the product page) shows seems a lot like FETs :

fets.jpg
 
He didn't contradict me, but whatever.

If you prefer that BMS I guess go for it then.
But please test if the BMS is reliable, I'd like to know.

I have quite a bit of experience with Battery building, and let me tell you. There is a lot of garbage ones, so I'm always wary.
 
I have just purchased this BMS https://aliexpress.com/item/Free-shipping-1pcs-smart-display-3-2V-3-7V-300A-lithium-battery-protection-board-balanced-management/32741659733.html

I will report here once I have received and tested it. will take a few weeks though
 
You will probably need more than 15P of cells for 300A. Each cell will do 20A but there will be a lot of voltage sag and it will get very hot (this will be worse with multiple cells built into a pack). The cell datasheet will tell you by how much.

Depending on the application you might even consider RC lipo as it is good at high power, just less reliable and more explode-y.
 
Really sorry for advertising project on several threads, but since this has not been mentioned here, have a look at this TinyBMS:
https://www.energusps.com/shop/product/tiny-bms-s516-150a-750a-36

Up to 750 amps if used with current sensor.
You can connect external contactor of use integrated high side switch to power only motor controller's logic supply (connect power leads directly to battery via fuse).
 
Erenaud, how did you make out with your bms and battery for the openppg? I am also getting the openppg batch4 and want to build an 18650 pack. I’m not actually sure that bms is required, couldn’t you also just wire in a 13s balance connnector and use a lipo/li ion balance charger?

Also want to know why you went with 13s instead of 14 since the openppg can handle 14s? What batteries did you use? How does it fly, flight times on your battery?
 
+1 for TinyBMS

I use one and I like it. And it's the only sane and safe way to switch 300A in my opinion.
 
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