Can anyone help with what I thought would be a simple task - a child's electric bike ?
It is a pretty straightforward set up - 12v DC charging port, 6V battery and simple push to go operation (no speed control). Even though the charger is marked as 6V it outputs 11.2 V !
So far I have checked the charging circuit which seems to be working (shows 7.2 V with the charger on and the battery reads 6.2 v with the charger off). The handle bar switch shows continuity when pressed, the battery will drive the motor when connected direct, it just doesn't seem to work off the switch (shorting the switch makes no difference either).
There are 2 black boxes on the wiring loom - one on the positive battery lead I assume is a fuse (marked 5A) this seems OK (continuity across it and volts from the charger get through it. The other one I am not so sure about, but I guess it regulates the charging voltage down ?
Can anyone suggest what the other component is or what troubleshooting I can do next ?
I am wondering if I should just rig up my own wiring so it is direct connect to the motor to drive it and a charging circuit that charges the battery at 6.5 V or something.
https://www.flickr.com/photos/139281.../shares/gJ6fH9
Has it got a brake?
Sometime the brake lever has a micro switch that also shuts off the motor.
If not could be regulator or throttle perhaps.
Strangely enough I have a quad that doesn't want to go now, but did 2mths ago....new batteries, new throttle, wiring checked.
I suspect its just down to cheap failed components on mine and have just given up.
^^ Good idea from Keith to check the brake for a kill-switch, maybe also the side-stand (as they use to have in motorcycles)?
Someone who lies about the little things will lie about the big things too.
The black box dangling in the air is a relay. The handlebar switch will be a low current switch energizing the relay which connects the battery to the motor.
Take the relay down to Maplins and ask them for a replacement.
You will need to desolador the dead relay and solder the new one back in.
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Thanks for the advice - it doesn't have a throttle or brake just on/off and no other kill switches etc.
Regarding the relay - can I bypass it to test it - ie short across it or is it more complicated than that ?
It does look like that must be the only failed component left now !
How many tabs does it have and are they numbered ie 31, 15+ etc.
If they are it should make it easy finding a replacement as these will identify the inputs/outputs.
it it doesn't then just check whether it energises when you turn it on off
It doesn't look like a normal 12V relay - here are some closer photos.
Come to think of it I must have a 12V headlight relay or two kicking around so I could cut the whole lot out and test with that easily enough.
https://www.flickr.com/photos/139281.../shares/03f30D
https://www.flickr.com/photos/139281.../shares/1HzKc8
The top red & black wires (from the handlebar switch) have continuity across them without the switch being pressed. Disconnecting the switch they still have continuity so they are internally connected at the moment. The hb switch wires only have continuity when the button is pressed in.
Last edited by MB2; 3rd January 2018 at 17:46.
Definitely a relayOriginally Posted by MB2
This any good?
http://www.sanyourelay.eu/public/products/pdf/SARM.pdf
Thanks that is helpful ! I found the manufacturer's web site but that pdf lets me decode it.
SARM-S105D4
So it is Flux proofed (water proof would have been good for a kids bike), 1 Pole, 6 Volt, 0.8 W at the coil and of course switches 15A.
I think I will try and test the relay, and then try an old relay as next steps.
Some 12V automotive relays will work at 6V, if you have one lying around then it’s worth trying.
The only thing that may happen is 6V may not be enough to energize it so nothing will happen when you press the handlebar switch.
Without knowing how everything else is wired I wouldn’t like to say which of those contacts on the relay you could short together to test - if the toy only has forward, and the circuit goes from battery - fuse - motor - relay - battery then shorting out the bottom two wires should make the motor work. I hesitate in saying that because the wires to the handlebar switch seem suspiciously heavy duty, they only need to be thin wires to carry the current needed to energize a relay, so please don’t short the bottom two together unless you’ve got spare fuses!
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Thanks - I have had a closer look at the wiring and I am now really confused !
There is a charging circuit which charges the battery (via a diode). The same wiring is also used to send power from the battery to the relay. The switch has continuity when pressed and goes back to the relay.
The -ve from the motor runs to the relay. The +ve from the motor terminates at the charging port but does not have continuity with anything so I expect that is the problem (although it doesn't look like it should be connected to anything I think it has to be ?
Testing the charger port the -ve and +ve terminals have continuity to the -ve and +ve wires but not to the motor.
Please see a sketch of the wiring diagram attached and the charging port.
https://www.flickr.com/photos/139281.../shares/kY8CRD
https://www.flickr.com/photos/139281.../shares/Kn3m16
I think the easiest is if I make my own circuit unless can help with what is wrong with this one ?
Last edited by MB2; 4th January 2018 at 11:51.
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