BMS Trouble ???

[Marky T]

Hi all,

My battery was doing really well, roughly 23 miles till 1 out of the 3 red lights on the handlebar console started to go out under load, when checking the lights on the top of the battery, it would show just the first green light out, at this point I would put it on charge, which would take around 4 hours.
All was fine until the other week, coming back from work I noticed the console light going out after only about 9 miles then all the power cut out, come back on cut out etc.
I put the battery on charge it only seemed to charge for about 2 hours then indicated full. I have had the battery output tested which is indicating 40 volts, when I set the level to high and set the throttle on high cruise, I am able to apply the brake directly using th caliper lever, hence applying load, when I do this the lights on the battery drop right down then all the power cuts off. I have observed that just before the power cuts off, all the lights on the handlebar console remain on, they don't even flicker, this leads me to beleive that the motor controller is still receiving an healthy voltage. The battery is a 36v LifePo 9Ah, about 16 months old and done about 1200 miles. I was advised to do a factory reset but this had no effect. Anyone got any ideas??

Thanks Mark

 

[NRG]

It sounds like one of the cells has become weak. The only way to really check is to break into the battery and measure the voltage on each cell. Not something I would advise you to do unless you know what you are doing and have handled these batteries before. They can give a tremendous amount of energy if shorted...

 

[Marky T]

Hi NRG

Thanks for the reply, it could be what you say, however with the overall voltage at 40 volts and the motor controller not showing any loss in voltage. I'm just not sure. Anyone else had any similar problems?

 

[onmebike]

Hi NRG

Thanks for the reply, it could be what you say, however with the overall voltage at 40 volts and the motor controller not showing any loss in voltage. I'm just not sure. Anyone else had any similar problems?

Whats the voltage reading under load? You can have good voltage readings without load but, the battery may be unable to supply the necessary amps due to a faulty cell, faulty connection's between cells, bms or battery and controller. Try monitoring battery voltage at controller under load, if it falls dramatically its likely to be faulty connections or cells as described above. The bms will cut power if it detects a voltage drop below the set voltage, it may then reconnect once voltage recovers depending on design of bms. The controller may also cut power when voltage drops with the same effect. The description of power cutting in and out indicates insuffient amps reaching controller in my opinion.

 

[Marky T]

Thanks Onmebike,

I am thiinking of purchasing a turnigy watt meter, if I wired this in, would this show up any faults?

Thanks

 

[Marky T]

It sounds like one of the cells has become weak. The only way to really check is to break into the battery and measure the voltage on each cell. Not something I would advise you to do unless you know what you are doing and have handled these batteries before. They can give a tremendous amount of energy if shorted...

Well looks like you was right NRG, I dismantled my battery the other day and found one cell to be very swollen, (see attachment). I would be grateful if anyone could give me info' on cell suppliers. The cell dimensions are: H155mm x W90mm x D8mm approx' Thanks Marky T

 

[Blew it]

Sorry to hear about this battery failure

Those LiFePo4 batteries were supplied with a two year warranty, have you contacted Simon or Darren?.

If all else fails, you could keep the Trek running with a QBP 36 volt 10 ah battery currently available on Ebay. Unfortunately, when we started buying these batteries they whacked the price up to £250. Personally, I would pay a little extra for a Phylion battery, available as replacements for the Synergie Mistral and others. This may entail swapping the bottom cover. The main reason I purchased a QBP battery was because the Phylion batteries were unobtainable at that time.

I hope you succeed in bringing the Trek back into use, they were really good bikes.

Regards
Bob

 

[eddieo]

Have not heard of the Rush Trek's for a while......Are they still available, as they seemed good value.

 

[Blew it]

Gone but not forgotten

Afraid not Edd. Even the Spanish version, the Tucano has now been discontinued. It's a shame really, as these machines were most suitable for shorter riders, probably the lowest stand-over height possible with 26" wheels.

I was very fortunate to replace my own stolen Trek ( Voyager ) with a twelve month old Tucano for £350.

 

[NRG]

Well looks like you was right NRG, I dismantled my battery the other day and found one cell to be very swollen, (see attachment). I would be grateful if anyone could give me info' on cell suppliers. The cell dimensions are: H155mm x W90mm x D8mm approx' Thanks Marky T

Ohhh yes, that's gone. Not sure where you would get individual cells but cell_man over on the Endless-Sphere forum may be able to help if you know the cell manufacture or type...

 

[Marky T]

Its Alive

Sorry to hear about this battery failure

Those LiFePo4 batteries were supplied with a two year warranty, have you contacted Simon or Darren?.

If all else fails, you could keep the Trek running with a QBP 36 volt 10 ah battery currently available on Ebay. Unfortunately, when we started buying these batteries they whacked the price up to £250. Personally, I would pay a little extra for a Phylion battery, available as replacements for the Synergie Mistral and others. This may entail swapping the bottom cover. The main reason I purchased a QBP battery was because the Phylion batteries were unobtainable at that time.

I hope you succeed in bringing the Trek back into use, they were really good bikes.

Regards
Bob

Hi all,

Changed the cell on the battery today, gave it a quick charge and took it around the block on full assist, seemed ok, happy to have my silver machine back. Thanks all.

Marky T

 

[NRG]

Nice one! Where did you get the replacement cell from?

 

[Marky T]

Nice one! Where did you get the replacement cell from?

Cheers NRG,

Got the cell off of Simon, formally of 720cycles. I am going to try and find a supplier of this size of cell for the future, I can't warrant paying £200-£300, for a new battery when only one cell is defective, seems a waste of resources to me and not that good for the environment either. I can't understand why these cells are not easier to purchase and the batteries aren't built more moduler???

Thanks Marky T

 

[flecc]

Cheers NRG,

I can't understand why these cells are not easier to purchase and the batteries aren't built more moduler???

Development of lithium batteries has been both too rapid and too continuous due to failures, as a result the cell chemistries, cell constructions and BMS constantly altering, Once things stabilise we may be able to have a safe spares market, but I think that's still some way off.
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