KTM Elycan 27.5 with Panasonic rear motor

[Galaxya6]

Hi all..my Elycan has developed a strange fault. It’s worked find since I replaced the torque sensor.. I hadn’t used it for a while and with a fully charged battery about 3 miles into a ride the bike switched itself off.. I’ve had the battery apart and all cells read well and it charges up fine. Now it switches itself off after about 100 yards and the only way to restore control is to plug in the charger. When the charger is plugged in the bike will switch on then switches itself off after a very short while.. I’ve cleaned all the plugs and sockets and this has made no difference.. has anyone got any ideas? Thanks Ian

 

[Andy-Mat]

Hi all..my Elycan has developed a strange fault. It’s worked find since I replaced the torque sensor.. I hadn’t used it for a while and with a fully charged battery about 3 miles into a ride the bike switched itself off.. I’ve had the battery apart and all cells read well and it charges up fine. Now it switches itself off after about 100 yards and the only way to restore control is to plug in the charger. When the charger is plugged in the bike will switch on then switches itself off after a very short while.. I’ve cleaned all the plugs and sockets and this has made no difference.. has anyone got any ideas? Thanks Ian

Can you show us how you measured your battery, what its nominal value is, and what readings did you make from where inside please? A Photo or two maybe?
Are you also certain that your meter is accurate?
Did the battery sit long and unused before the problem started?
The only way to be certain (and please DO NOT consider even doing it!), is to separate each and every cell and measure each one FULLY (several tests of capacity!) as an individual.
For a battery that is too much unpaid work!
You may consider, assuming that you are electrically "FIT" as a flea, in separating the individual big blocks of cells, as I would guess that at least one of these blocks is at least partially defective, but also not an easy task, plus physically dangerous if you make a mistake.
I hope that I am 100% wrong and that someone here can give you far better assistance.

I am not recommending either procedure as I believe that your battery has a major failure in it.
Replacement or re-celling from a recommended (here) workshop. Some Pedelecers know good workshops in the UK....
regards and all the best for Easter and your Battery.
Andy

 

[Galaxya6]

Hi all..my Elycan has developed a strange fault. It’s worked find since I replaced the torque sensor.. I hadn’t used it for a while and with a fully charged battery about 3 miles into a ride the bike switched itself off.. I’ve had the battery apart and all cells read well and it charges up fine. Now it switches itself off after about 100 yards and the only way to restore control is to plug in the charger. When the charger is plugged in the bike will switch on then switches itself off after a very short while.. I’ve cleaned all the plugs and sockets and this has made no difference.. has anyone got any ideas? Thanks Ian

The battery LEDs light up in sequence low to high that indicates a battery fault. Though at the same time I get this on the display..

 

[Galaxya6]

Can you show us how you measured your battery, what its nominal value is, and what readings did you make from where inside please? A Photo or two maybe?
Are you also certain that your meter is accurate?
Did the battery sit long and unused before the problem started?
The only way to be certain (and please DO NOT consider even doing it!), is to separate each and every cell and measure each one FULLY (several tests of capacity!) as an individual.
For a battery that is too much unpaid work!
You may consider, assuming that you are electrically "FIT" as a flea, in separating the individual big blocks of cells, as I would guess that at least one of these blocks is at least partially defective, but also not an easy task, plus physically dangerous if you make a mistake.
I hope that I am 100% wrong and that someone here can give you far better assistance.

I am not recommending either procedure as I believe that your battery has a major failure in it.
Replacement or re-celling from a recommended (here) workshop. Some Pedelecers know good workshops in the UK....
regards and all the best for Easter and your Battery.
Andy

Hi Andy it was in storage for as long as I have had the bike.. and when I checked the battery there was something odd. When I plugged the charger in it showed 3 LEDs.. I measured across each cell group and each group was good.. I suspect ( which is a bugger) that the control board (BMS) is goosed…

 

[sjpt]

Sounds like a nearly dead battery. Full voltage when charged, but drops immediately under load.
If you look at the display as you manage the 100 yards does the indicator remain on full bars, or does it drop very rapidly?

 

[Galaxya6]

Sounds like a nearly dead battery. Full voltage when charged, but drops immediately under load.
If you look at the display as you manage the 100 yards does the indicator remain on full bars, or does it drop very rapidly?

Hi, the display holds up with full capacity but it just switches straight off without any warning.. no indication of an issue with capacity/range.. in fact if the battery was weak it wouldn’t show the mileage range like it does I would have thought .. thanks Ian

 

[Andy-Mat]

Hi Andy it was in storage for as long as I have had the bike.. and when I checked the battery there was something odd. When I plugged the charger in it showed 3 LEDs.. I measured across each cell group and each group was good.. I suspect ( which is a bugger) that the control board (BMS) is goosed…

How long have you had the bike?
Are you aware of the need to keep Li-ion batteries, always somewhere between their low and high point (vehemently discussed often here!), when not using the battery?
I don't think its the BMS myself, but I await other opinions, but to me it looks just like a bad battery, and someone else here appears to have the same opinion.
Best wishes and keep us all updated.
Andy

 

[sjpt]

in fact if the battery was weak it wouldn’t show the mileage range like it does I would have thought .. thanks

I think you are optimistic about how clever the mileage range indication is. Voltage is probably its only way of guessing how much charge there is. It can't distinguish between a good battery and a less good/bad battery till its had time to learn.

I'd expect the charge indication to drop before the motor stops, but sometimes that indication is slightly damped rather than instantaneous so it wouldn't have time to drop.

 

[Andy-Mat]

I think you are optimistic about how clever the mileage range indication is. Voltage is probably its only way of guessing how much charge there is. It can't distinguish between a good battery and a less good/bad battery till its had time to learn.

I'd expect the charge indication to drop before the motor stops, but sometimes that indication is slightly damped rather than instantaneous so it wouldn't have time to drop.

Good post. My thoughts exactly.
regards
Andy

 

[Galaxya6]

Good post. My thoughts exactly.
regards
Andy

Thanks guys.. I think I am fighting with this and the battery is knackered.. I’ll crack it open again. I have a ‘tester’ I can load check each bank of cells without taking the battery apart.. can use the connections to the BMS.. this wil detect a faulty set of cells hopefully! Thanks for all your help..

 

[Andy-Mat]

Thanks guys.. I think I am fighting with this and the battery is knackered.. I’ll crack it open again. I have a ‘tester’ I can load check each bank of cells without taking the battery apart.. can use the connections to the BMS.. this wil detect a faulty set of cells hopefully! Thanks for all your help..

It may only be one cell in one bank......and it only shows up when current is drawn, it would appear, though it will usually be more cells than one.... Difficult to tell as you need to draw some current and simultaneously watch the voltage (and all while riding! Sorry, joke!!)
Its not easy to test...
regards
Andy

 

[Benjahmin]

Hold on - too complex.
Get a digital voltmeter. Measure output voltage fresh from the charger - should be 41.6 or7.
Measure voltage after cutout.
Might be useful to check charger output voltage too.

 

[Nealh]

I would go one further and temporary wire up a meter to 100% watch what the voltage does. The issue may be controller or display related if the V's hold up.

 

[Galaxya6]

It may only be one cell in one bank......and it only shows up when current is drawn, it would appear, though it will usually be more cells than one.... Difficult to tell as you need to draw some current and simultaneously watch the voltage (and all while riding! Sorry, joke!!)
Its not easy to test...
regards
Andy

Hi Andy.. battery stripped and measured across with load tester and one of the banks was low.. all others fine..found a rusty cell. Using this cheap tool.. great for testing 18650 cells!

 

[Andy-Mat]

Hi Andy.. battery stripped and measured across with load tester and one of the banks was low.. all others fine..found a rusty cell. Using this cheap tool.. great for testing 18650 cells!

Well done!
You are the first person that I know of, who has managed to identify such a defect.
Keep us informed please.
regards
Andy
PS. Good clear photos as well!!

 

[Galaxya6]

Well done!
You are the first person that I know of, who has managed to identify such a defect.
Keep us informed please.
regards
Andy
PS. Good clear photos as well!!

Hi Andy.. I bypassed the duff cell and one of the others and charged the remaining 6 cells up to 3.8V as the others using a separate charger. When I plug the charger in when all cells are balanced the charger flashes indicating a battery fault. Can’t believe it can detect two cells are out of circuit but maybe it can.. Have attached some photos!

 

[Nealh]

The interconnector contact flow through that cell group is wholly compromised so the BMS can sense an issue, it simply won't switch to allow charging.
Even if it did one would still see the bike switch off after a 100yds because the one group with two cells would sag heavily and hit lvc, you have 12 parallel cell groups of four and one of the middle cell groups only has two viable cells in the P group.

What ever the original capacity is (let's say 14ah) is now actually only 7ah with two cells taken out of the P group, the battery is only as good as the weakest cell group.

The only thing one can try is to remove some of the plastic cell holder from one side and remove the two duff cells with similar cells, re weld the cells with a bit of new nickel to the existing nickel on both sides ( or try and flatten reuse the existing and hope the BMS hasn't bricked. As long as both of those yellow sense wires remain attached you might be alright.

 

[Galaxya6]

The interconnector contact flow through that cell group is wholly compromised so the BMS can sense an issue, it simply won't switch to allow charging.
Even if it did one would still see the bike switch off after a 100yds because the one group with two cells would sag heavily and hit lvc, you have 12 parallel cell groups of four and one of the middle cell groups only has two viable cells in the P group.

What ever the original capacity is (let's say 14ah) is now actually only 7ah with two cells taken out of the P group, the battery is only as good as the weakest cell group.

The only thing one can try is to remove some of the plastic cell holder from one side and remove the two duff cells with similar cells, re weld the cells with a bit of new nickel to the existing nickel on both sides ( or try and flatten reuse the existing and hope the BMS hasn't bricked. As long as both of those yellow sense wires remain attached you might be alright.

Sounds like a plan.. got two shiny cells charged up and ready to go in..got tabs on the battery so will be very careful soldering them!

 

[Nealh]

The two cells need to be at the same voltage of the other cells and have similar discharge specs. If soldering and nor welding the interconnector back on keep the heat on the cell to a minimum esp on the negative end of the can. Tin the cell ends with a good blob of solder or the tab , use wooden or plastic tool to flatten the interconnector as best as possible. Apply solder to the more solder so it flows nicely to aid fusion with the blob underneath, the solder should ooze between the slits in the interconnector.

Hopefully the BMS will allow charging if it isn't compromised.

 

[Galaxya6]

The two cells need to be at the same voltage of the other cells and have similar discharge specs. If soldering and nor welding the interconnector back on keep the heat on the cell to a minimum esp on the negative end of the can. Tin the cell ends with a good blob of solder or the tab , use wooden or plastic tool to flatten the interconnector as best as possible. Apply solder to the more solder so it flows nicely to aid fusion with the blob underneath, the solder should ooze between the slits in the interconnector.

Hopefully the BMS will allow charging if it isn't compromised.

Hi, thanks for that sound advice. Have assembled the battery though out of the case.. I get 54V with my DVM… sadly when the charger is plugged in the LED still flashes .. I’ve put the battery on the bike and it reports 96% capacity which to me is a true load and not just a volt meter..is there a way of resetting the main control board to the battery BMS?