Need Help with Battery BMS

wozwasted

New Member
I just changed my BBS02B 750w motor for a BBSHD 1000w and my battery cant give the motor the power that it needs, it cuts out after discharging to only 48v. I need to know if I can change the BMS in my battery from a 48v 25w to a 48v 30w? and could this fix this problem? I really want to avoid buying another battery if I have other options available
 

harryS

Well-Known Member
I believe you meant to say ..."can I change my BMS from a 13S 25A unit to a 13S 30A unit?". You can, but you might be waiting for two months to get it out of China these days. I got some little widgets on order, and they've been stuck for 3 weeks now, with the company not even open because of the virus lockdown. It's also a pain to replace a BBS. Relatively straight forward, but still a pain. I've done it a few times.

I think though, that even if you changed the BMS, it's not the current limit in the BMS that is shutting down the battery at 48V, it's voltage sag in the cells. So Thomas' suggestion to limit the current in the BBSHD to that of the BBS02 sounds good.

I always ran my BBS02 on batteries rated for 30A draw, but I don't think it drew that much power except under throttle.
 

wozwasted

New Member
I probably should give a bit more info on whats happening...
I had no problems with the battery while using the BBS02B motor, the battery is A 48v 13Ahr 25w and is around 8 months old.
After I fitted the new motor I turned it on and even though I fully charge the battery, the display shows it is 54.5v but only 3/4 full. I can ride until the battery discharges to 48v, by then it has droped to empty then shuts down.
Ive tried looking in the Bafang config tool and the low cut off is set to 41v and the current limit ive tried on 28A which is as high as it would let me go, I also tried it on 25A.
Is it possible that I may need a Battery with more AHrs? or does anyone know what else I should look at?


Ive just been for a ride and the battery is showing empty and the bike is slowing down enen though there is still 49.4v available.
I just reconected my original motor and the display also shows that there is still 49.4v BUT it also displays the battery as FULL.
Could this be a problem with my new motor?
 
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AHicks

Well-Known Member
I don't know a thing about the internal controllers, but on an external controller bike, thinking either the BMS -OR- the controller could shut the power down at a given point.

My point is, you stated the old motor was fine, but the new one was cutting out. My thought is regarding the potential for this to be a controller issue, NOT the BMS? Is it possible the new motor's controller isn't set correctly for this application?
 

wozwasted

New Member
That is what im thinking but the place I got it from are trying to say I need a new battery. Im sending the motor back along with my battery on Monday, so Ill be walking again for a while, It could be worse, at least I didn,t buy it from China. Ill let you know how it goes

46204
 
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AHicks

Well-Known Member
It looks to me like SOMEBODY needs to figure out how to program that controller. Regarding the stuff I am more familiar with, the display is reading the controller, NOT the BMS!
 

wozwasted

New Member
I used the Bafang Config tool an it was set to 41v for the cut off. that was the only setting which has anything to do with this problem. Im sure your right the controller has been programed wrong and its at an Admin level so the Config tool cant fix the problem
 

indianajo

Well-Known Member
from a 48v 25w to a 48v 30w? and could this fix this problem?
You keep saying the battery is 48 v 25 w. I don't know what battery has 25 w limit, a flashlight battery?
The 48 v battery I bought from lunabikes has no wattage limit spec. It has a 50 A limit which at 41 v would be 2050 Watts. I bought two trash batteries, one from amazon btrbattery and one from e-bay sun ebike (Baldwin City CA warehouse). After fully charging I tried to draw 4.8 A from them with a 10 ohm 450 watt resistor and the first collapsed to 11 v, the second collapsed to 7 v. I made the 10 ohm 450 watt resistor by putting in series two 5 ohm 225 watt resistor logs I bought from apexelectronic surplus of Sun Valley.
I don't know who will take battery back after more than 31 days for refund, good luck.
 

Thomas Jaszewski

Well-Known Member
I used the Bafang Config tool an it was set to 41v for the cut off. that was the only setting which has anything to do with this problem. Im sure your right the controller has been programed wrong and its at an Admin level so the Config tool cant fix the problem
Can I ask who it came from?
 

wozwasted

New Member
My original motor is a 750w and runs at 25A, When I go into th Bafang config tool, on my new motor I should be able to set it to 30A but the highest it will aaccept is 28A, When I bought the kit it wasn't stated what it was, I was assuming it must be 25A due to the power problems, however, I tried another battery and the same thing happens so im certain the problem is the controller on my new motor.
The photos should explain the problem im having more clearly
 

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Thomas Jaszewski

Well-Known Member
Why ship it back? Have them send a new controller. Who did you purchase from? I can’t believe a seller would have you ship a battery and entire motor for a simple controller replacement. thats an expensive warranty return and replacement. May as well learn how to change out a controller, someday it may happen again. BTW 25A on my BBSHD’s was hardly noticeable. Some think it’s a more reliable motor at 25A.
 

wozwasted

New Member
I sent back my motor and Battery to Pirez, Apparantly the problem is that the new motor is a 52v and my battery is 48v (even though I ordered a 48v BBSHD motor and they don't even advertise a 52v motor).
Anyway they changed the Controller and are sending it back, Hopefully the problem will be fixed