Need help with my e bike

[Sami fouad]

Hello is there any one that had a problem with his ebike... The issue is that my ebike goes off sometimes when i use it... When i turned it on it shows all that power are full while i move on the power assist looks like goes down gradually as far as i pedal when i stop pedaling the power assist comes full again..thanks in advance

 

[sjpt]

You need to say what type of bike, in particular what type of controller.

 

[Nealh]

More details needed like battery age, cells make/type and controller ampage.

What you describe could be an ageing battery that can't handle the load demand asked of it, typically know as voltage sag. Sag is a result of cells with high IR (internal resistance/capacity loss ) due to ageing or abuse to due to too high a load asked of the cells according to the spec sheet.

With a ageing /tired battery it shows a full charge and often high/normal voltage for it nominal value, when a load is applied the drops suddenly to cause a cut out. Once the load is removed the voltage has time to recover and after a few seconds it bounces back to quite full again, this is until a load is applied again and the cycle begins over again.

 

[Sami fouad]

You need to say what type of bike, in particular what type of controller.

Hello its roodog chic e bike. Its a 250watt rear wheel hub brushless motor. The battery is a 36 volt 10Ah, lithium-ion.

 

[Sami fouad]

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

 

[Nealh]

What assist level do you riding in and under what circumstances does the battery/bike cut out ?

 

[Sami fouad]

I put the third level even if its in the first level it cuts out.. When i turn the throttle also it cuts out. So no light in the display i have to turn the key so as to start again

 

[Nealh]

Battery needs replacing, but to be sure connect a volt meter to the two wires between battery and controller. Lift the wheel off the ground and use the PAS/throttle and watch the voltage if it collapses then the battery is scrap.

 

[Sami fouad]

Battery needs replacing, but to be sure connect a volt meter to the two wires between battery and controller. Lift the wheel off the ground and use the PAS/throttle and watch the voltage if it collapses then the battery is scrap.

I tried the voltmeter is not accurate it shows 1 and when i hold the bike up turning the throttle nothing changes. It shows 1

 

[Nealh]

I tried the voltmeter is not accurate it shows 1 and when i hold the bike up turning the throttle nothing changes. It shows 1

You likely haven't set the volt meter up correctly as it should at least show the battery voltage before you do anything, it should read between 32v and 42v depending on the SOC (State of charge).
The dial should be set to DC range or V and on the 200v setting and not AC range or A.

 

[Sami fouad]

Hello i have bought another voltmeter and it shows 39.4 v when i hold it up and turn the throttle it shows 39.9 v

 

[Nealh]

Hello i have bought another voltmeter and it shows 39.4 v when i hold it up and turn the throttle it shows 39.9 v

Ok now you need to create some load and demand the battery to output some power, so whilst using the throttle gently use the brake so that the wheel still turns. This will draw higher amps from the controller which will demand the battery to work harder, see what the voltage does.

 

[Nealh]

I tried the voltmeter is not accurate it shows 1 and when i hold the bike up turning the throttle nothing changes. It shows 1

Probably just needs a new 9v battery.

 

[Sami fouad]

Hello putting load means that i have to sit on it or put weight amd hold it up??

 

[BazP]

Hello putting load means that i have to sit on it or put weight amd hold it up??

No, whilst you hold the wheel off the ground and turn the throttle get someone to apply the break gently to put pressure on the wheel without stopping it turning.

 

[Nealh]

Hello putting load means that i have to sit on it or put weight amd hold it up??

The load required is theoretical power load by means of amps drawn and not a physical weight load.
Putting a load on means making the electrical system work harder, the battery is the power source (the weak link), the controller is what provides the load by means of powering the hub. By gently applying the brake it will make the wheel harder to turn, the controller will try and draw more watts from the battery to supply the amp load. If the battery is at fault the voltage will sag/collapse dramatically causing a cut out.

 

[Sami fouad]

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

 

[Nealh]

Right your battery has had it then, the cells will have high to very high internal resistance which is assign of ageing and is detrimental to cell capacity.
It is time to send the battery to a recycling centre or possibly use them for a torch.

 

[Sami fouad]

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

 

[soundwave]

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

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