Lipo BMS

[heathyoung]

Unfortunatly, I have had similar experiences with the headway packs and that capacitive BMS - It wasn't from this seller, but I get the feeling that these are just drop-shipped, with little to no assembly work being carried out by skilled workers.

At least the balance wires were soldered on the one I ordered (for someone else) - but the screws on the cells were also finger tight, and the capacitive balancing BMS had drained one cell badly - you could see where a transistor had actually burned a hole in the PCB. Needless to say it got replaced and rebuilt properly, and again reinforced the old adage - if you want something done properly, do it yourself - and - you get what you pay for.

Lifepo4 is a dead duck in my opinion - too bulky, overly optimistic discharge rates etc.

 

[eva-michael]

Unfortunatly, I have had similar experiences with the headway packs and that capacitive BMS - It wasn't from this seller........quote]
From last few months after we made the new capacitor BMS installation instructions with long details, we dont get feedback about BMS issue again. If anyone meet this issue, please post here or contact us. Some customers are purchase single BMS order from us also.

We should not say too much as this may just cause more misunderstanding. But we just dont hope that some misunderstanding about a BMS connection diagram last year causes more misunderstanding in this year.
Capacitor BMS is a good BMS solution as it has a much better cells balance function.

Another thing which we think is very importance. LiPO is easier to match and synchronization than LiFePO4. And we just provide good match cells to customers or in our battery pack. But this feature indicate that the C rate of LiFePo4 in battery pack is different from C rate of LiFePO4 cell. 0.5-3C will be ideal for headway. This point should be easy to be understand.

 

[Arlo1]

SO I should ask it here. What if I want to run more then 50 amps the the motor? Like 200-500 amps is it possible to just use the bms for balancing and charging? Can I just wire the hi tension wires to the battery and use the balance leads for the bms?

 

[neptronix]

Seems like you could do that just fine.. but you'd lose your LVC and whatever cell-level LVC there is with a BMS.
I would think it would then revert to basically being just a top-level balancer.

 

[Wattever]

I was thinking of using a low current BMS in my high power setup by bypassing the BMS's discharge FETS to the controller, however taking a wire from the BMS output and feeding the on/off switch with it - this way when the BMS cuts off the controller will think someone had clesed the switch.
Usually the on off switch is feeding the logical circuit of the controller - when the BMS cuts, the controller will shut down. I did not test it, and I have noticed sometimes when my BMS shuts down I still have some voltage on the battery, so I am not sure it will work...

 

[Arlo1]

I was thinking of using a low current BMS in my high power setup by bypassing the BMS's discharge FETS to the controller, however taking a wire from the BMS output and feeding the on/off switch with it - this way when the BMS cuts off the controller will think someone had clesed the switch.
Usually the on off switch is feeding the logical circuit of the controller - when the BMS cuts, the controller will shut down. I did not test it, and I have noticed sometimes when my BMS shuts down I still have some voltage on the battery, so I am not sure it will work...

You could just have it turn on the brakes or somthing? It could pulse the brakes or ground a pin for one of the three speed settings and that would be a slower setting so you would feel the power go away. There is lots of ways rather then having it turn off the controller.

 

[Trackman417]

Apparently Ilia at ebikessf.com sells a lipo BMS. However he does not provide a warranty, unless if he attaches the BMS to the lipo pack with his own bare hands. I deleted the emails I had from him regarding getting the BMS. However if it was coming from him, you know that it would be quality, and not some cheap chinese crap. However for a 20S BMS he was talking around $150. But the cost will be deterred off by the fact I can sell my balance charging set up, unless if I needed it for charging new packs.
That will be for next year for me.