Ebike kit battery problems

t4tal

Just Joined
Dec 4, 2015
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Not sure if this is the right place to post this as this is my first time.
the kit i have is a 8fun 250w rear hub.
36v 10Ah lipo4
on a Norco VFR hybrid bike.

So i bought a ebike kit, came and I installed it. As it was my first ride I let the battery fully charge.
Now my commute is roughly 4-5 miles going and about the same coming back, so around 10-12 miles in total. when i unplugged the battery it was around 41.55, so I went on my daily, however on the way back when the battery reached around 38.15V~, the motor would not run any more. I checked all the wiring when i got home, and thought that something went wrong, however the next morning on a battery with a close to full charge did the exact same thing. It works fine on the way, but on the way back, it will stop working when it reaches 38v. From my knowledge i believe that the battery actually finishes when it reaches 32V~. So i did this for more day to see if it would happen. again and obviously it did. I have tried keeping the battery inside, which doesnt affect the range at all.
So my question is is there something i have overlooked, or is the battery just faulty.
Thanks a lot guys :D
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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To me it sounds like the batteries BMS's (battery management system) LVC (low voltage current) is set way to high. Have you spoken to your kit supplier ?
 
Last edited:

t4tal

Just Joined
Dec 4, 2015
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1
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is there a way to lower the bms?
He asked me to fully charge it and leave it like that so the bms can auto balance the cells, but that didnt work so...
 
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Nealh

Esteemed Pedelecer
Aug 7, 2014
20,888
8,518
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West Sx RH
The bms is a pcb its the lvc that's may need correcting by re programming.
41.55v is quite good and show cells are fairly well balanced in time with further charges you should see 42v eventually but shutting down at 38v indicates the lvc is too high.
Some lcd's can be used for 24/36/48v systems if it is set up for a 48v system then it would shut down early but that is at about 40v, they have a parameter that can be set for the correct voltage.