Motor cuts out.

[Dawes700]

Recently on a 20 mile ride the motor cut out about 5 times but restarted if I switch the 'ignition' key on and off.
Checked for loose connections etc and found one I suspected might be dodgy. Soldered, reassembled but same fault.
Thinking maybe a faulty 'ignition switch' I bridged the switch, tried this morning, failed after 2 miles and wouldn't restart at all.
The electrics are an Alien Ocean front wheel conversion kit about 5 years old. Only an on/off switch and the throttle are connected, no pedelecs, no brake lever cut offs - nothing.
The battery was upgraded to 36v 15Ah by Jimmy at BGA in Nov. 2016. Fully charged it puts out 41.2

It's this type of battery although I suspect it's irrelevant
Any ideas, suggestions, help, gratefully received.
Dawes 700

 

[Nealh]

41.2 v suggests a cell group may be out of balance, if the cell group sags enough under load then it will bring lvc in to play. Once the load is reduced the voltage recovers and it will be above lvc so will work again until the sag under load starts the sequence of events again.

The fault may even be a bad weld/cell connection, unfortunately the only way of knowing what is actually happening is to open the battery and measure the 10 groups of cell voltages or let Jimmy see if there is a fault.

An other possible fault may be the battery connection at the rack so check the connections to make sure there is no problem with poor contacts, though this is more likely if it happens due to uneven surfaces.

 

[Deleted member 4366]

What do you mean by "ignition switch"? I didn't think that the Alien kit had one.
Do you have battery lights on your throttle? If so, do they go out when the power cuts?

 

[Dawes700]

Hi d8veh
I used the term ignition switch as a sort of layman's description for the key operated lock/switch on the side/end of the battery.

No, the throttle doesn't have lights and the on/off lights gizmo failed about 6 months ago, so I substituted a simple handle bar mounted on/off switch.
PS. Came home bike not having been touched for about 4 hours, switched on - it works but presumably - as previous experiences show - won't last.
Dawes 700.

 

[Deleted member 4366]

Without battery indicator lights or similar on the handlebars, it's very difficult to get to the cause of your problem. You need something like a voltmeter to show the voltage in real time so that you can see whether the battery voltage is down at the time of cut-off.

 

[Nealh]

D8veh is on the ball again, a simple cheap watt or volt meter wired in would show what is happening voltage wise prior to cut off.
Which cells did you go with ?
20 miles then turning off sounds like it might be lvc coming in to play esp if under load.

 

[Dawes700]

Without battery indicator lights or similar on the handlebars, it's very difficult to get to the cause of your problem. You need something like a voltmeter to show the voltage in real time so that you can see whether the battery voltage is down at the time of cut-off.

Thanks d8veh
I thought, what a good idea, went out yesterday with a voltmeter did about 16 miles, never missed a beat.
Damn!
I'll get back if/when it happens next.
Dawes 700

 

[Dawes700]

D8veh is on the ball again, a simple cheap watt or volt meter wired in would show what is happening voltage wise prior to cut off.
Which cells did you go with ?
20 miles then turning off sounds like it might be lvc coming in to play esp if under load.

See my reply to d8veh.
Thanks d8veh
I thought, what a good idea, went out yesterday with a voltmeter did about 16 miles, never missed a beat.
Damn!
I'll get back if/when it happens next.
Dawes 700

 

[Dawes700]

See my reply to d8veh.
Thanks d8veh
I thought, what a good idea, went out yesterday with a voltmeter did about 16 miles, never missed a beat.
Damn!
I'll get back if/when it happens next.
Dawes 700

D8veh is on the ball again, a simple cheap watt or volt meter wired in would show what is happening voltage wise prior to cut off.
Which cells did you go with ?
20 miles then turning off sounds like it might be lvc coming in to play esp if under load.

The cells used by BGA were Boston Power cells
Dawes 700.

 

[Deleted member 4366]

That at least means that your cells are OK. You're probably looking for a bad connection somewhere.

 

[Dawes700]

I agree, although I've already pushed, pulled, tugged and wiggled everything in sight.
If I do sort it I'll let you know.
Thanks again,
Dawes 700