Need help with my e bike

[Sami fouad]

yes if you have a spot welder and nickle/copper strips.

And what kind of batteries i have to purchase?

 

[Nealh]

It's not economical on an old failing battery.
A good capable spot welder is about £130 and then needs a £40 or £50 lipo battery to power it, add on the price of cells about £3 - £5 each, nickle strip and a few other bits . The cost starts mounting up to that of a new battery or simply send it off to ebikebatteries .co.uk to be re-celled for about £300.

 

[Nealh]

Can't repair de battery?? Putting other new cells

Only viable if it was quite a new battery, then as above you need the knowledge and capable equipment to carry out a good lasting repair.

 

[soundwave]

And what kind of batteries i have to purchase?

2 X Samsung INR 18650-30Q 3000mAh 20A

2 X Samsung INR 18650-30Q 3000mAh 20A

bga-reworking.co.uk

they can recell the batt for you

 

[Nealh]

The battery has 2 years abd and 5 months.. Not sure about what type of controller.

How have you looked after/charged the battery ?
Do you charge to full all the time and let it sit all the time at 42v?

 

[Nealh]

2 X Samsung INR 18650-30Q 3000mAh 20A

2 X Samsung INR 18650-30Q 3000mAh 20A

bga-reworking.co.uk

they can recell the batt for you

Not very helpful posting 30q cells to suggest to OP they are suitable, his battery will be using 2a or 2.5a cells. All we probably know is that a 18659 cell of some description is used.

 

[Sami fouad]

How have you looked after/charged the battery ?
Do you charge to full all the time and let it sit all the time at 42v?

Now its 39.2 i don't use it much when has this problem

 

[Nealh]

Is 39.2v the most is charges to ?

 

[Deleted member 25121]

Yes that's what i tried.. I hold it up and drop it down to touch the floor while i turn the throttle.. I can see that voltage get down to 34, 35 v and it collapses

So you lift up the back wheel, run the motor up and drop the wheel on the floor to stall it?
You need to lift up the back wheel, run the motor up and monitor the voltage when you also gradually apply the rear brake.

 

[Sami fouad]

So you lift up the back wheel, run the motor up and drop the wheel on the floor to stall it?
You need to lift up the back wheel, run the motor up and monitor the voltage when you also gradually apply the rear brake.

yes i drop it gradually and i saw that voltage is getting down until it collapses

 

[Sami fouad]

yes i drop it gradually and i saw that voltage is getting down until it collapses

The thing that i can't understand is while im pedaling the battery loss power. And when i stop pedaling the power assist comes full energy again

 

[Deleted member 25121]

yes i drop it gradually and i saw that voltage is getting down until it collapses

Did you try applying the brake instead of dropping the bike gradually?

 

[Deleted member 25121]

The thing that i can't understand is while im pedaling the battery loss power. And when i stop pedaling the power assist comes full energy again

Yes, that is strange and it could be caused by a number of things. The first step is to test the battery under load using the bake, as several of us have suggested.

 

[Sami fouad]

Yes, that is strange and it could be caused by a number of things. The first step is to test the battery under load using the bake, as several of us have suggested.

I have tried once again turning the throttle and braking it shows 39.5 go up to 40 when the wheel stops

 

[sjpt]

I'm surprised nobody has mention Jimmy at https://bga-reworking.co.uk/product-category/all-products/e-bike-batteries/ for battery rebuild.
Seeing there are people much more knowledgeable than me already contributing to this thread maybe they know why it wouldn't be appropriate in this case. If so I'd be interested in the reason to increase my knowledge.

 

[Nealh]

I have tried once again turning the throttle and braking it shows 39.5 go up to 40 when the wheel stops

What actually does the voltage read when you se the brake if it collapses before rising to 40 volts then the battery is finished.

Please listen and read carefully what we are saying.
Voltage collapse happens when the battery cells are knackered, a knackered cell can hold high volatge because there is no current load asked of it, once a load is asked of the cells they collapse. The voltage collapse is due to high IR which means the cells have reached end of life, high IR and voltage sag /collapse go hand in hand. Once the load demand is released the voltage goes up again because it gets a chance to rest.
Think of it like running the harder you run the more out of breathe you get, when you stop running and rest your breathing becomes easier.

 

[Nealh]

I'm surprised nobody has mention Jimmy at https://bga-reworking.co.uk/product-category/all-products/e-bike-batteries/ for battery rebuild.
Seeing there are people much more knowledgeable than me already contributing to this thread maybe they know why it wouldn't be appropriate in this case. If so I'd be interested in the reason to increase my knowledge.

Jimmy will likely carry out a simple load test on the battery as he does with new ones he builds to check all is well, his conclusion will be they are knackered. You can't repair cells as they are weakened by the chemical reactions inside that have led to cell break down and high IR, mixing new cell with old cells isn't cost effective. Doing so you might as well give your money to the next man in the street who might make better use of it.

 

[Nealh]

Sami needs a new battery then his problem will be fixed, it's that simple.
You can't reverse voltage sag/collapse with old knackered cells.
Problem is Sami doesn't answer some of the questions asked or carry out the simple tests as we ask, so we don't get the correct answer we are looking for.

For instance lifting the wheel and applying the brake slowly, not drop the bike on the ground to stop the back wheel. Also when applying the brake to apply a gentle load someone needs to see what the voltage does at the same time.

 

[sjpt]

Jimmy will likely carry out a simple load test on the battery as he does with new ones he builds to check all is well, his conclusion will be they are knackered. You can't repair cells as they are weakened by the chemical reactions inside that have led to cell break down and high IR, mixing new cell with old cells isn't cost effective. Doing so you might as well give your money to the next man in the street who might make better use of it.

Thanks for the response. I can certainly see there is no point in replacing just some cells; but not why a complete recell (by Jimmy) might not be appropriate. Perhaps for easily available batteries a new battery is cheaper than a recell?

 

[Deleted member 25121]

Sami needs a new battery then his problem will be fixed, it's that simple.
You can't reverse voltage sag/collapse with old knackered cells.
Problem is Sami doesn't answer some of the questions asked or carry out the simple tests as we ask, so we don't get the correct answer we are looking for.

For instance lifting the wheel and applying the brake slowly, not drop the bike on the ground to stop the back wheel. Also when applying the brake to apply a gentle load someone needs to see what the voltage does at the same time.

It's odd though because Sami reports "The thing that i can't understand is while im pedaling the battery loss power. And when i stop pedaling the power assist comes full energy again " ie the battery can give full power but not partial power. This contradicts what he said when he applied the brake with the wheel off the ground "I have tried once again turning the throttle and braking it shows 39.5 go up to 40 when the wheel stops" ie the battery can't give full power??

Maybe there's an issue with the PAS sensor or display/controller. I think a competent cycle shop could be the first port of call rather than getting the battery recelled.