E-bike not turning on - where to start?

[Mr Horace Wimp]

So my e-bike (which I had professionally converted) is not turning on. It's the type with a motor in the hub, a throttle with on/off switch on the handlebars, a battery pack and a control unit.

I am kind of suspecting (and hoping) it's just the throttle that's faulty. Maybe the on/off switch itself. I GUESS it could also be the battery terminals which may have corroded some. Any tips??

(There is a hyperlink in the message linked to the word throttle which shows the type of throttle I have).

I have a multimeter to hand.

THANKS

 

[Deleted member 4366]

We'll be making wild guesses without seeing what you have. What kit is it? Can you show us photos of the controller and what you have on the handlebars?

If you want to know whether your controller is switched on, check the voltage between the throttle's red and black wires. 5v is on, 0v is off.

 

[Mr Horace Wimp]

Hi d8veh

I'll take some pics tonight. In the meantime I've made some measurements wit the multimeter. 37v on the battery so that's fine of course. HOWEVER, as soon as I connect the battery to the circuit/control board, I can't read any voltage off the battery anymore. What could possibly cause that??

Thanks

 

[Danidl]

Hi d8veh

I'll take some pics tonight. In the meantime I've made some measurements wit the multimeter. 37v on the battery so that's fine of course. HOWEVER, as soon as I connect the battery to the circuit/control board, I can't read any voltage off the battery anymore. What could possibly cause that??

Thanks

Pictures would help. But what is the expected battery voltage?. A fully charged 36v battery pack should be reading closer to 41volts newly charged. A fully charged 24v pack should be around 29 30 If the charger had failed , the voltage across the unloaded battery will be about 35 to 36 and cannot provide any current. I would suggest checking the voltage available on the battery. 1, 5 and 10 minutes after removal from a charger.

If one or more of the tiers in the battery pack was basically knackered, it will still provide the correct voltage off load, but if asked to supply a current through it, has a very high resistance and the overall voltage of the battery falls to a few volts at most.

 

[Mr Horace Wimp]

H Danidl, that's useful information and helpful - but in some ways it's a side issue isn't it(?) to the main problem that even the LEDs on the throttle don't turn on and when I measure voltage on the control board none of those 36v are seemingly present - and I'm reading at the very soldered points they meet the board! ?
Confused.

 

[Danidl]

H Danidl, that's useful information and helpful - but in some ways it's a side issue isn't it(?) to the main problem that even the LEDs on the throttle don't turn on and when I measure voltage on the control board none of those 36v are seemingly present - and I'm reading at the very soldered points they meet the board! ?
Confused.

Did you not say that when you disconnected the battery pack it was reading 36v but when it was connected you could not measure 36v ,( I am assuming accross the same points ). If so it is because the battery cannot supply current.
You would not expect to see 36v around the electronics near a throttle,. I would expect a normal supply of probably 5v and 1.8v accross a working red led.
The normal practice is for the battery to supply the controller via a main fuse and probably a keyswitch. The controller will condition the voltages for the Throttle and other sensors as well as generating the time sequenced voltages to the motor.

 

[Mr Horace Wimp]

Sorry Danidly this is almost certainly down to me explaining poorly and not yet having provided the pics you all understandably want to see!

Let me clarify (thanks for bearing with...!)

-I can measure 36v across the battery when it's not connected to the circuit board.
-I cannot measure ANY voltage whatsoever across the circuit board when the battery is connected. I am measuring the ends of the cables coming from the battery to where they are soldered onto the board.

This seems odd to me.

(THROTTLE NOT INVOLVED IN THESE TESTS.)

 

[Deleted member 4366]

36v is not enough! Charge up the battery. It should be 41v to 42v when the charging is finished. If you only have 37v, it's faulty - most likely a duff cell in the cell-pack.

If you have a battery with a duff cell, you can read 37v on the output, but as soon as you try to draw any current (connect to a controller), the voltage collapses and the BMS switches off.

You need to test one thing at a time, starting with the battery.

 

[Mr Horace Wimp]

d8veh - OK, that makes perfect sense when you put it like that. Sorry, wasn't trying to be difficult.
Thank you!