Battery only charging partially

Nealh

Esteemed Pedelecer
Aug 7, 2014
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The battery shouldn't work at all if #4 is 0v as this cell bank is dead , the BMS should be sensing a fault and refusing to switch to allowing a charge. Also #1 & #3 are quite low so should trigger lvc much sooner.
I for one would be very cautious of this pack and certainly wouldn't continue charging.

Repeat the first four voltage checks incase there was an error in testing .

What ever occurs now don't persist with this cell pack , take it to your local recyling centre for just that recyling .
 

Chris Maluszynski

Pedelecer
Jan 26, 2015
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The battery shouldn't work at all if #4 is 0v as this cell bank is dead , the BMS should be sensing a fault and refusing to switch to allowing a charge. Also #1 & #3 are quite low so should trigger lvc much sooner.
I for one would be very cautious of this pack and certainly wouldn't continue charging.

Repeat the first four voltage checks incase there was an error in testing .

What ever occurs now don't persist with this cell pack , take it to your local recyling centre for just that recyling .
It sounds like this could actually be dangerous?
Should I be worried?
 

Woosh

Trade Member
May 19, 2012
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Southend on Sea
wooshbikes.co.uk
Unplug the charger, use the battery for an hour or until it stops working then take it to the recycling station. As it is faulty, don't charge it again.
 

Chris Maluszynski

Pedelecer
Jan 26, 2015
217
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49
Scary stuff. And now I'm without a bike which I'm very dependent on (I live on an island with no cars, and need to haul everything for 2km on the bike to the house from the ferry).

I do however have a 54V sharkfin battery. If the cells fit in the Wisper case, maybe I could replace the pack? Or would 54V kill the controller on the Wisper?
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
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3,241
Telford
Scary stuff. And now I'm without a bike which I'm very dependent on (I live on an island with no cars, and need to haul everything for 2km on the bike to the house from the ferry).

I do however have a 54V sharkfin battery. If the cells fit in the Wisper case, maybe I could replace the pack? Or would 54V kill the controller on the Wisper?
Don't panic just yet. Do the tests that Neal suggested. Something doesn't quite add up with the measurements you made, so repeat them first before you decide what to do. Nothing has changed from before, and it didn't blow up the previous times you charged it, but do it in the garden rather than your kitchen, just in case.
 

Woosh

Trade Member
May 19, 2012
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Southend on Sea
wooshbikes.co.uk
Don't use the 48v battery on a 36v kit, it will cause even more trouble than your present problem. You only need a modest but new 36v battery.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
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Don't use the 48v battery on a 36v kit, it will cause even more trouble than your present problem. You only need a modest but new 36v battery.
What??? Putting a 48v battery and controller would be a good solution for any 36v Wisper bike. If I had any 36v bike that had a failing battery, I'd always upgrade to 48v, except in some fringe situations.
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
7,005
3,241
Telford
Scary stuff. And now I'm without a bike which I'm very dependent on (I live on an island with no cars, and need to haul everything for 2km on the bike to the house from the ferry).

I do however have a 54V sharkfin battery. If the cells fit in the Wisper case, maybe I could replace the pack? Or would 54V kill the controller on the Wisper?
It wwould probably damage the controller, but controllers are cheap and you can use the opportunity to get a better one.
 

Chris Maluszynski

Pedelecer
Jan 26, 2015
217
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Ok. Maybe i even have a 48v controller somewhere. But it would be so much easier to use the one on the bike as I wouldn’t have to switch displays, brakes etc right?
 

Woosh

Trade Member
May 19, 2012
20,451
16,916
Southend on Sea
wooshbikes.co.uk
What??? Putting a 48v battery and controller would be a good solution for any 36v Wisper bike. If I had any 36v bike that had a failing battery, I'd always upgrade to 48v, except in some fringe situations.
His commute is modest, he does not need a big battery. Even a tool battery may work for him. If it were me, I would hook up a 10ah or 15ah saddle bag battery and sort out his problem in 5 minutes. A bag battery would usually fit inside behind seat post battery cases.
 

Chris Maluszynski

Pedelecer
Jan 26, 2015
217
1
49
Another measurement confirms the dead cell bank. I guess this means the BMS is faulty also then?

3.3
7.4
11.0
11.0
15.1
19.1
23.2
27.3
31.3
35.4
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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West Sx RH
Take a voltage reading direct off the battery pack from the cell with the thick Black wire to the cell with the Thick Red wire.

If that cell group is dead then the battery shouldn't work and yes looks like the BMS is faulty if the battery is still usable.
 
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