Charged battery cuts out.

[Boncwen]

My battery shows 75% charged but keeps cutting out after a few miles ride.

Anyone have any idea where I should look for a fault?

 

[soundwave]

its voltage sag as the cells get older they store less power over time esp if you are using max amps.

tho a cell bank could be out of wack voltage wise but will need to take it apart and check all of the voltages on the bms.

 

[saneagle]

My battery shows 75% charged but keeps cutting out after a few miles ride.

Anyone have any idea where I should look for a fault?

It should show fully-charged after you charged it. You should tell us the whole story about it if you want to sort it out.

 

[Nealh]

Out of balance or knackered , we haven't enough info to go on.

 

[Boncwen]

Out of balance or knackered , we haven't enough info to go on.

Thanks for getting back.

Yes, I am sorry. More info.

Battery was 100% charged at start of journey. Battery is about 18 months old since new.
On a 20 mile journey I pedal and use epower and usually have no problems getting home with at least 25% power left in the battery which then gets recharged again to 100%

Today the battery shutdown time after time but on resetting, that is switching the key off on the battery and back on again the battery meter was still showing charge at 75%. The meter on my throttle display was also showing similar. But as soon as I applied gentle throttle while physically pedalling the battery cut out again.

 

[soundwave]

batt is knackered as that what voltage sag does imo it was cheap and why it dont last long.

 

[Nealh]

Was it 100% balance charged ?
One needs to confirm full charge voltage with a meter reading.

If a cell group is unbalanced then it will act as you have seen.

If the full charge is circa 42v then the battery is showing advanced signs of aging , the voltage sag is indicative of an aging battery.

 

[ste harvs]

I can repair it

 

[saneagle]

My battery shows 75% charged but keeps cutting out after a few miles ride.

Anyone have any idea where I should look for a fault?

There are 26,339 different ebikes and 5,281 different batteries. Which one would you like me to explain how to fix?

 

[Nealh]

Probably a bot or spam post @d.h.

 

[saneagle]

Probably a bot or spam post @d.h.

I thought the post was from OP. I've now edited it.

 

[Nealh]

I thought the post was from OP. I've now edited it.

Sounds like he may be legit , say's he is a battery repairer in anothe rthread intro..

 

[Boncwen]

Was it 100% balance charged ?
One needs to confirm full charge voltage with a meter reading.

If a cell group is unbalanced then it will act as you have seen.

If the full charge is circa 42v then the battery is showing advanced signs of aging , the voltage sag is indicative of an aging battery.

The battery in question is now showing 100% charge, all green LEDs are showing on the battery. Also the red light on the charger has turned to green. Putting a meter on the battery outputs -tive and +tive, volts are 41.5V.

On a spare battery which has so far demonstrated no faults, the output reading is 42.1V

 

[Nealh]

41.5v is ok , it is at the lower end of what one can expect.
It is likely that voltage sag and an aging /tired battery is the issue , if the cutting out continues.
If it is a speed control controller then one can't do much about it , if one had a current control controller then one could use a lower PAS level and current to eke out more miles and help prevent the cutting out.

Issue with speed control device is it will ask for max current so the current demand is near maximum and voltage sag will be an issue, as the battery volatge drops due to usage then the voltae sag will take the battery SOC lower down to the LVC (low voltage charge ) threshold .
AT rest the voltage sag will easily rebound and rest above the LVC, the battery will work again for a short distance then the sag occurs again down to LVC and the reocurring cut outs carry on.

If this is the case then the only option is to buy a new battery and take the old one for recycling.

 

[Boncwen]

41.5v is ok , it is at the lower end of what one can expect.
It is likely that voltage sag and an aging /tired battery is the issue , if the cutting out continues.
If it is a speed control controller then one can't do much about it , if one had a current control controller then one could use a lower PAS level and current to eke out more miles and help prevent the cutting out.

Issue with speed control device is it will ask for max current so the current demand is near maximum and voltage sag will be an issue, as the battery volatge drops due to usage then the voltae sag will take the battery SOC lower down to the LVC (low voltage charge ) threshold .
AT rest the voltage sag will easily rebound and rest above the LVC, the battery will work again for a short distance then the sag occurs again down to LVC and the reocurring cut outs carry on.

If this is the case then the only option is to buy a new battery and take the old one for recycling.

Thanks for your comprehensive reply.

Sounds I need a new battery.

Thanks again