Giant Twist - battery problem?

[Brian Sussex]

I hope you may be able to help.

My wife Trish’s Giant Twist has developed a fault whereby the battery appears to charge properly and, when fitted to the bike, shows a full hand of red lights but, within only a few yards, the e-assist stops and the red lights drop back to two.

The battery registers 28.77v after a full charge. Does this sound about right please?

Not sure if it is the battery, the charger or something in the control units that is at fault.

Might someone be able to help with a diagnosis please?

Many thanks

Brian

 

[sjpt]

Could be an old battery. It would charge to the full voltage, but as soon as you tried to take any current from it the voltage would fall right down.

 

[Nealh]

28.77v suggests it is a 7s/24v battery, the voltage is low if that is the finished charge. It should charge fully to 29.4v.
28.77V equates to 4.11v per cell group which is low and if true is an indication the battery is shot, the load applied causes severe voltage sag another indication the cells inside are shot. Once the applied load is removed the lights should go back up. The final nail in the coffin is the e-assist stops so although you have 2 Red leds one or some of the cell groups will be hitting rock bottom.
You can double check your charge plug on the charger is out putting 29.4v, if so then again your battery is likely shot.
You will need to consider a new battery or a re-cell.

How old is the battery ?

 

[Brian Sussex]

Thank you for the battery info osjpt and nealh - much appreciated.
Something odd happened earlier. I put the battery back in the bike so that I could check its voltage after discharge but, surprisingly, it just kept going. Eventually I got bored going up and down the road so parked it up with all the red lights still shining!
I will take it for a decent run tomorrow to see if the battery continues to behave. Just hope my luck holds!
If it doesn't I will do further checks.
Brian

 

[Nealh]

Anomalies do happen maybe you hadn't placed the battery in position correctly or the discharge pins were making bad contact.