Battery Suddenly Dead

[RichardM]

I was riding my 806 Torque the other day and as it was getting dark I turned the light on. As soon as I did this the display went off, the light came on and went off immediatley and all assistance was lost.
The display wouldn't turn on again. The battery was nowhere near fully charged but had "enough" charge left. When I got home I tried charging the battery. Nothing happens when I plug the charger in.

I assumed that the way the power was lost suddenly was an indication of a fuse blowing, however I can't see a fuse anywhere. Does a bank of cells suddenly fail like that? Could the BMS suddenly fail and cause this? Does anyone have anyother ideas?

 

[matthewslack]

A bank of cells is unlikely to fail like that without some serious indications of the smoke, fire, smell and noise variety.

May well be a fuse issue. Ask Wisper?

 

[RichardM]

A bank of cells is unlikely to fail like that without some serious indications of the smoke, fire, smell and noise variety.

May well be a fuse issue. Ask Wisper?

A fuse is what I expected but there is no sign of any fuses. I am hoping Wisper will reply here.

 

[matthewslack]

Perhaps inside the battery.

If so, next question is why did it blow? Had anything unusual happened, perhaps water related, or was the bike dropped?

 

[Nealh]

Take a battery voltage reading using a meter, see if there is a reading .
Not all batteries have an accessible fuse behind a gommet cover, but would be surprised if a Wisper battery didn't have.

 

[RichardM]

I opened the battery up. No sign of a fuse inside the case. Nothing unusual happened, I just turned the light on.
I've just checked the voltage on the power out terminal. 17.5v and drops to zero when I press the button that shows the charge level.
To me that looks like about half the cells dead. Unless a lead has become detached.

 

[Nealh]

17.5v indicates a BMS issue , for some reason the BMS isn't switching on.
Via the BMS sense wire connector one can get all of the 10 cell group voltages to see if the issue lies with a bad cell group.
If all the cells are good and above LVC then one is likely looking at a BMS failure.
Typically LVC is 2.9v - 3.1v per cell group.

 

[RichardM]

17.5v indicates a BMS issue , for some reason the BMS isn't switching on.
Via the BMS sense wire connector one can get all of the 10 cell group voltages to see if the issue lies with a bad cell group.
If all the cells are good and above LVC then one is likely looking at a BMS failure.
Typically LVC is 2.9v - 3.1v per cell group.

Thank you. For some reason in this battery the BMS is under the bank of cells (not at one end like in all the videos that I could find) so not easy to get to without detaching the cells which are very firmly held in place by some kind of glue.
In one video, where it was determined that some cells were dead the guy levered them out with a big screw driver, while saying "don't do this"!

 

[saneagle]

Thank you. For some reason in this battery the BMS is under the bank of cells (not at one end like in all the videos that I could find) so not easy to get to without detaching the cells which are very firmly held in place by some kind of glue.
In one video, where it was determined that some cells were dead the guy levered them out with a big screw driver, while saying "don't do this"!

You must have had a short on the light wire that's easy to damage on most bikes, so check it carefully.

I can't see any way that could damage your battery, but clearly something has gone wrong in the BMS, as it's switched off. I'm wondering if it just needs a reset, which can normally be done by unplugging the multipin connector and plugging it back in.

It looks like you'll have to face your demons and hoik the cell-pack out. Do not use a screwdriver unless you have good house insurance. You need a wide flat piece of wood or similar.

 

[RichardM]

You must have had a short on the light wire that's easy to damage on most bikes, so check it carefully.

I can't see any way that could damage your battery, but clearly something has gone wrong in the BMS, as it's switched off. I'm wondering if it just needs a reset, which can normally be done by unplugging the multipin connector and plugging it back in.

It looks like you'll have to face your demons and hoik the cell-pack out. Do not use a screwdriver unless you have good house insurance. You need a wide flat piece of wood or similar.

I have a spare battery that I have been using since this happened. The lights work fine with that.
I hope you are right that unplugging and unplugging the connector works. I'll report back later.

 

[Wisper Bikes]

I was riding my 806 Torque the other day and as it was getting dark I turned the light on. As soon as I did this the display went off, the light came on and went off immediatley and all assistance was lost.
The display wouldn't turn on again. The battery was nowhere near fully charged but had "enough" charge left. When I got home I tried charging the battery. Nothing happens when I plug the charger in.

I assumed that the way the power was lost suddenly was an indication of a fuse blowing, however I can't see a fuse anywhere. Does a bank of cells suddenly fail like that? Could the BMS suddenly fail and cause this? Does anyone have anyother ideas?

Hi Richard what did the guys in Wisper support suggest?

 

[RichardM]

Hi Richard what did the guys in Wisper support suggest?

I haven't spoken to them yet

 

[Nealh]

Use only non metallic tools for prodding or poking around batteries , common sense will tell most to do so.
Some of those idiots who post utube videos are a danger to themselves let alone someone watching.

 

[Wisper Bikes]

I haven't spoken to them yet

Hi Richard.

Maybe it would be a good start, if there is a way to help they will do so. 01732 762393. Chose option 2.

All the best, David

 

[RichardM]

You must have had a short on the light wire that's easy to damage on most bikes, so check it carefully.

I can't see any way that could damage your battery, but clearly something has gone wrong in the BMS, as it's switched off. I'm wondering if it just needs a reset, which can normally be done by unplugging the multipin connector and plugging it back in.

It looks like you'll have to face your demons and hoik the cell-pack out. Do not use a screwdriver unless you have good house insurance. You need a wide flat piece of wood or similar.

I phoned Wisper, they suggested sendingb the battery to a business, that when I checked their website seemed to sell cycles and motorbikes amongst other things but had no indication that they repaired ebike batteries.
Instead I contacted https://www.tech-nic.co.uk/ in Bristol who arranged for the battery to be collected. They diagnosed a wiring fault and a BMS issue. They fixed the wiring and reset the BMS then promptly got the battery back to me.
I'd be happy to recommend them.

 

[Wisper Bikes]

They are a battery re-cell company Richard. As it says in the front page of their website.

“IS YOUR E-BIKE BATTERY ACTING UP?
Is your current lithium battery suffering from diminished range, stuttering under load or not working at all? With over 6 years’ experience in the lithium-ion ebike battery industry and a full suite of testing and welding equipment, not to mention our strict safety procedures, you can leave your battery with us in confidence. Contact us to learn more.”

We use them occasionally but it’s cheaper for you if you go to them directly. Give them a call.

All the best, David