KTM e-race battery pack repair. Bionx 250W

The intent of this post is to share the experience I had on repairing my BionX Ktm Battery pack.

Here you can find the bike specifications: http://tmp.ktm-bikes.at/e-bike/e-bike/eRace.php?lang=EN

The Motor is a:
BionX Nabenmotor „KTM Edition 2013” 250W HighTorque

The Akku: Motor 48V, Akku 52 cells = 8,8Ah = 423 Wh

After few mounts of inactivity probability the battery pack discharged too much and I couldn't recharge it anymore, it was pissing me off with a cyclic BIP every few minutes.

I did try then opening the enclosure and after disconnecting the 2 main + and - cables of the battery I did try recharging the battery with an external power charger directly into it. I didn't have a 48 power supply, I just used a 24V car battery charger (I have limited the change to 2A).


opening the case

After around 30 min of charge I connected back the the battery to the main board and packed everything back and finished charging with the Bionx power supply, yes this time after 30 min of direct charge the original charger was working. Unfortunately this second charge took very long time, around 10 hours and I could feel the battery pack becoming unusually hot during the charge.
Tested the bike and it worked immediately quite well but after few days (without recharging) the display started showing weird symbols and the bike was shooting down. Battery don't charge anymore again...

New battery pack from BionX cost 750 Euro, 1/3 of the entire bike price. Way too expensive, decided opening the battery wrapping and inspect individually the batteries.

Lable

The battery pack is composed by 13 series of 4 Parallels for a total of 52 batteries.

4P 13S

Nominal voltage 3.62, Max 4.2.
2 out of the 13 parallels was at 0.5V. I have tried to brake the parallel and recharge the batteries individually.

If you try doing this please consider safety as a matter of priority, use safety glasses at least, Lithium battery can explode easily. As a basic rule never supply the battery with more than 4.5 V and the current shouldn't never exceed 750mA to remain in the safety side.

Unfortunately none of the battery was maintaining the charge.

brake the parallel

Ordered on ebay 10x same SAMSUNG batteries at the price of 64 EUR including DHL shipment. I ordered from this site because the batteries come with a plate already soldered to the ends of the batteries.
http://www.ebay.de/itm/Samsung-ICR-18650-22P-2150mAh-3-7V-Loetfahne-Z-/321678359433?ssPageName=ADME:L:OC:IT:3160

battery

Replaced the 8 bad batteries, charged, Packed everything back and went out for a ride. Noticed on the bike display the battery was not charged 100%. The bike worked fine at the beginning but after 1 hour or so the display in diagnostic mode was showing error code 41 and the battery was stopping providing power to the motor.
Back home opened everything again and measured the voltage for each one of the 13 parallels. 2 Of them were at 2.6v, charged those 2 parallels individually. Discharged with a 6v halogen lamp adn recharged again. Recharged the entire pack again with the Bionx official power supply and tested again. This time the bike was charged 100%. Tested on the street with max level of assistance for few hours, no problem. Did another full charge and finally tested offroad on the center of Italy mountains for various hours.



with 64 Euro and many hours of work at night while the baby was sleeping managed to save 685 EUR and recovered my lovely bike.

Do you have a photo post assembly with the new cells before you re-wrapped?

I'm just learning about S and P cell configurations here. Can someone enlighten me as to why there is a single group of 4 cells and the rest are 8 cell groups?

goodgnus
there are 13 series of parallels of 4 cells.

the 8 cells you see are 2 series of 4 parallels.
If you pay close attention to the picture you'll see that 4 of them have the + in common and the other 4 have the - in common, in other words, they are in series.

congrates to the successful repair^^
its not a given that the electronic board still is ok after exhaustive discharge.
i have about 10 bionx packs here with 6.2b board revison thats same like yours. about half of them are 4p and the others 3p configuration (they may be called small and big type). Mine have not Samsung 22p - they are made with Sony V2 cells.
now here comes the really bad thing: from the 10 packs only one had good electronic, while the others ether did show abnormality during charge / usage or had been completely dead (blown parts).
The bionx electronic is one of the most complex i have ever seen in ebike and many different versions are around. That might be the reason why its so prone to break.

madin88,
I guess is not possible to buy the single board individually??

no, i have not seen it available as new. recently i found some used in the net (ebay as example), but non of them with guaranted function

sassa said:

goodgnus
there are 13 series of parallels of 4 cells.

the 8 cells you see are 2 series of 4 parallels.
If you pay close attention to the picture you'll see that 4 of them have the + in common and the other 4 have the - in common, in other words, they are in series.

Click to expand...

So each block of 8 cells is 2s4p which doubles the voltage and quadruples the mAh rating, correct? The 4 cell block is 2s2p which doubles the voltage/mAh. Is that right?

-Tom

Tom,

So each block of 8 cells is 2s4p which doubles the voltage and quadruples the mAh rating, correct?
YES

The 4 cell block is 2s2p which doubles the voltage/mAh. Is that right?
NO, the 4 cell block is just 1P, one parallel of 4 cells.

Paolo

A Bionx ebike owner stated that he had the same problem, and discovered that the faint beeping was the battery pack discharged too much.

It also would not charge from the charger.

However, he pedaled the Bionx bike and got the pack to the point that it would take the charge, normally.

A Bionx ebike owner stated that he had the same problem, and discovered that the faint beeping was the battery pack discharged too much.

It also would not charge from the charger.

However, he pedaled the Bionx bike and got the pack to the point that it would take the charge, normally.

4LivesPerGallon said:

However, he pedaled the Bionx bike and got the pack to the point that it would take the charge, normally.

Click to expand...

yes, pedalling and slightly push the brake lever so it turns into regen can bring it back to life again, but only if its not too deep discharged i think.
but before doing so, its better to open the battery and check all single cell volts. if they are above 2V it should be ok - below i would not do it.

Exactly,

The battery pack has 17 pairs of wires going to board.
13 of them to monitor the cells voltages and 4 for the temperature.
I cannot be sure but I assume if the voltage of one of the 13 cells is below a set point value the electronics will disable the charge.
if even one of the cells is bad and cannot recharge then it needs to be replaced.