Issue with Rockrider E-ST 100 Battery

Carrie-anne

Just Joined
Jul 11, 2020
4
0
Brand new bike from decathlon arrived with 3 battery lights on and instructions saying to charge it to full before it's first use and that this could take up to 24 hours. 24 hours later the batter still only has three bars. Took it into our local decathlon store who gave me a puzzled look, plugged it in, gave me another puzzled look and shrugged before saying they had no idea why it wouldn't charge and would order me a knew one. Then told me to use what battery I did have if it would work because a new batter would take a minimum of 2 weeks to arrive and once discharged some may charge back up to three or further.

Not particularly happy to be told to knowingly use a faulty batter in regards to any possible warranty violations but I did wonder if anyone on here had any ideas as to why a supposedly new battery would be unable to accept a charge. Unfortunately I don't have access to a multimeter at the moment but my neighbour (a builder) is going to ask the leccy at work on Monday to see if he can spare me one for a day or 2.
 

wheeliepete

Esteemed Pedelecer
Feb 28, 2016
1,906
688
58
Devon/Dorset
I can't see a problem with trying out the battery on the bike. It could be the case that the battery is close to having a full charge and will not take any more. Are you certain the charger is plugged in correctly and has power to it? Are there any lights on the charger?
 

Carrie-anne

Just Joined
Jul 11, 2020
4
0
I can't see a problem with trying out the battery on the bike. It could be the case that the battery is close to having a full charge and will not take any more. Are you certain the charger is plugged in correctly and has power to it? Are there any lights on the charger?
Yes the lights come on the charger. It flashes orange when plugged into my battery. I tried it on my mums this morning, her battery was fully charged and the light went green like it's supposed to, but when put back in mine it flashes orange again, same thing if using her charger. My mums bike and mine are almost identical only hers is white, mines is blue.
Interestingly enough her battery lights are constantly on until the battery is full, mine don't come on at all. I've been reading on here about unbalanced cells and how sometimes running them down a bit and then trying to charge them can 'reset' them so they charge up the next time round so may give it a go. I suppose even if it only every charges back up to 3 bars it'll be handy as a spare.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,931
Basildon
Get someone to measure the voltage on the charger connector, then on the battery charge connector. Those readings will tell you what's faulty, if anything. The charger should be around 42.0v and the battery should charge if it's anything between 29v and 42v, but it won't charge if it's already 42v or thereabouts.

It's most likely a blown fuse in the charger or battery when it should but doesn't charge.
 

Carrie-anne

Just Joined
Jul 11, 2020
4
0
Get someone to measure the voltage on the charger connector, then on the battery charge connector. Those readings will tell you what's faulty, if anything. The charger should be around 42.0v and the battery should charge if it's anything between 29v and 42v, but it won't charge if it's already 42v or thereabouts.

It's most likely a blown fuse in the charger or battery when it should but doesn't charge.
Thanks for the reply. We've had to order a multimeter because any shop we went in that should have any were out of stock, Screwfix, Halfords, Wickes anywhere we could think off. We were trying to borrow one but have decided with all of us having electric bikes (my mum has 2) that having one in the family might come in handy. So we'll have a look when it arrives. Still waiting for the replacement battery to come into the store in Decathlon. In the meantime I've been unable to have a proper go on the bike as I fell off my dad's and injured my elbow but over the last week I've still managed to rack up almost 20 miles and haven't been able to drop a bar of battery so that's impressive, I think. I generally don't need anything over eco for the short runs I've been on, in fact even the worst hill on the run (the one I used to have to get off and push on) is doable on eco if I push myself so despite the problems I'm really enjoying the bike so far. I'm definitely a pedelec convert.