Powabyke - appalled by battery

[KirstinS]

I took an old 6ah powabyke battery apart - suspected dead cells

I was shocked to find 30 x 18650 cells with no BMS whatsoever

Not suprisingly several cells were reading 0 volts

The rest were all over the place

Even worse - to my mind they were simply 3 x blocks of 10 cells in series

Surely better to have 3 cells in parralel and then series up 10 of them

Due to way pack built I can't even simply add a few balance leads in for occasional balancing. Total rebuild required

I just keep thinking of member whose garage blew up due to unprotected packs

Shocked a major company would do this

 

[jackhandy]

I told you that months ago

Keep up that man!

And mine were only 1500mha cells, which adds up to 4.5ah - for a 6ah battery

 

[flecc]

The X series batteries have always been suspect. These bikes were introduced with large cell batteries claimed as being 6 AH but for a long time only had 4.5 Ah cells. Their range was hopeless of course.

It's odd to have dropped battery standards so much with the X bikes. Possibly it's the desire for as small a bottle battery as possible, or just reducing cost.

Either way it's silly if they want a long term future.

 

[trex]

it's a bit more than dropping standard.
Frank Curran, where are you?

 

[flecc]

Frank was still there recently, but I think he could be inwardly groaning since the new ownership following bankruptcy.

 

[KirstinS]

I told you that months ago

Keep up that man!

And mine were only 1500mha cells, which adds up to 4.5ah - for a 6ah battery

Did you ? Oops - the sleep deprivation of having two kids under 4 dies funny things to the brain !

 

[Deleted member 4366]

Don't be too quick to judge! I think there's something special about the cells, Can you tell us the designation on the side? Try opening a dead one to see if it has internal protection like Ultrafire cells.

 

[shemozzle999]

Hi KirstinS,

Sorry to hear about your disappointing findings.

If you have still got the battery apart I wonder if you could be so kind as to post some photos of the internal wiring and components so that others might know what to expect to find if they ever need to fault find one.

 

[jerrysimon]

Makes my 36v, 3.0Ah DIY Konion packs with no BMS for £60 look like a bargain. Its a shame it's so hard to get cells shipped now.

I also have a 6Ah one as well, but it rarely gets used as the 3Ah is sufficient for my commute.

Regards

Jerry

 

[KirstinS]

Yes indeed good idea

 

[KirstinS]

Hope this makes sense

Canister with two screw off plates . One contains connector

3 x 10 cell packs wired in series to make 37v nominal

These are then linked in series

 

[KirstinS]

I'm individually balancing the cells and have replaced the 3 dead ones with as close as I can get to matching

 

[KirstinS]

Don't be too quick to judge! I think there's something special about the cells, Can you tell us the designation on the side? Try opening a dead one to see if it has internal protection like Ultrafire cells.

Ok they are unusual in that no printed markings. They are embossed

Says Sanyo ur18650w2

Sorry but I'm not comfortable taking a lithium cell to bits ! Even a dead one !

 

[shemozzle999]

Thanks for the photos.

 

[Deleted member 4366]

They're special high discharge rate cells - up to 20 amps each! So you can't replace one in the string with a low discharge rate one of equivalent capacity. It won't be able to give enough current.It might be better ti make two strings of the Sanyo cells, and then add one of normal cells.

 

[pdarnett]

Wish you'd said that a few weeks ago Dave when I had mine in bits!I didn't realise they were special cells, mine had no markings. I replaced my dead cells with 2.2Ah Samsungs! Mind you it's my spare "booster" pack, haven't used it in anger yet because of the no BMS issue.

 

[Deleted member 4366]

Wish you'd said that a few weeks ago Dave when I had mine in bits!I didn't realise they were special cells, mine had no markings.

I thought yours were Momentum batteries. Do they use the same cells?

 

[KirstinS]

They're special high discharge rate cells - up to 20 amps each! So you can't replace one in the string with a low discharge rate one of equivalent capacity. It won't be able to give enough current.It might be better ti make two strings of the Sanyo cells, and then add one of normal cells.

I've used high discharge cells from matika drill packs so think it's fine

US18650's they are

 

[trex]

kirstinS, are you going to fit a BMS to the repaired pack?

 

[pdarnett]

My flat cell pack is a momentum one, and thats fine, halfway through the rebuild thread I rebuilt a powabyke one as well, just like the one above. May have to take that back to bits now! Anyone know a good source for a few of these Sanyo ur18650w2's?