12v DC bike not running

[dabomb3k]

Hi guys I was hoping someone could help me with my sons bike, it doesn't appear to be charging and won't switch on...

I have a basic knowledge of things and how to use a multimeter but I just need pointing in the right direction of where to look..

I have plugged the charger into the socket and the socket has a red, black and yellow connection coming off the back of it (see pics) when I was testing for voltage across them, I accidentally put the meter across the yellow and the black cable and the bike powered up, the on off on the bike works and the bike runs fine when those wires are connected through the lead.. (Or any metal creating a conductor) but as soon as I take it off the bike dies again..

I have also chased the cables back to what looks like a 12v switch or transformer feeding the other functions of the bike and which feeds the 2 6v battery supplies... (The red black and yellow leads plug into this)

I know that the red is obviously positive, black negative shut Im unsure what the purpose of the yellow lead is.. I think the charger socket maybe faulty as the yellow and black cable should be connected at the socket and when I put metal across them it completes the circuit? Is this correct...

Otherwise could anyone maybe point me in the direction based on these pictures??

Thanks for your help!

Untitled

• dabomb3k
• 28 Dec 2014
• 1

Untitled

• dabomb3k
• 28 Dec 2014
• 1

Untitled

• dabomb3k
• 28 Dec 2014
• 1

Untitled

• dabomb3k
• 28 Dec 2014
• 1

Untitled

• dabomb3k
• 28 Dec 2014
• 1

[/b]

 

[flameport]

The yellow wire is used to prevent the motor running when the charger is plugged in.
When the charger plug is inserted, it breaks the contact between yellow and black. When the plug is removed, black and yellow are connected - or not in this case as the socket has failed internally.

You need a new socket. They are readily available, such as these: http://www.rapidonline.com/Cables-Connectors/Connectors-Mains-Power/DC-Power-Connectors
There are several different sizes of plug.

 

[dabomb3k]

Ah thanks flameport that explains a lot, is there a way to link out that yellow cable then so he can still use it and charge it in the mean time while I order a socket??

If I merely touch the black and yellow together without the charger plugged into the socket then it doesn't run..

 

[JohnW2]

If I merely touch the black and yellow together without the charger plugged into the socket then it doesn't run..

Are you saying that touching yellow and black together makes the motor run when the charger is connected, but not if the charger is not connected? If so, what voltage measurements do you get between the red and black connections at the battery (a) with charger plugged in and switched on and (b) with charger unplugged?

Kind Regards, John

 

[dabomb3k]

Hi john, yes that's what I'm saying, I will check the readings again now, I know I was getting 6v dc on each battery previously but can't remember if charger was in or not so will try again

 

[dabomb3k]

Okay I'm getting 6v off each battery without the charger plugged in..

I've messed with the cables.. If I plug the charger into the socket and put the black lead where the yellow one is and leave the yellow one unplugged the unit boot up fine and all works.. If I put use any other combination it doesn't,equally if I unplug the charger from the socket, nothing works no matter what I do

 

[JohnW2]

Okay I'm getting 6v off each battery without the charger plugged in.

One more experiment, if you haven't already done it. Without the charger plugged in, do you still get 6V across eah batter (or 12V across the two) if you attempt to turn the motor on?

I've messed with the cables.. If I plug the charger into the socket and put the black lead where the yellow one is and leave the yellow one unplugged the unit boot up fine and all works.

That would make sense if the unit was 'running' off the charger, rather thyan the battery. I would suggest that you don't leave it running for long like that, since the charger might not be up to the load.

If I put use any other combination it doesn't,equally if I unplug the charger from the socket, nothing works no matter what I do

I'll think again after you'v answered my latest question.

Kind Regards, John

 

[dabomb3k]

Hopefully I can explain this correctly

Across battery 1 + to - I get 6v

From battery 2 I get the same

If I do + to - across battery 1 to 2 I get 12v on the side that goes off into the bike

If I do the same across the other end which is just a looped bit of cable I get 0 volts (may have to check picture to understand what I mean )

As for checking with motor on Im not sure what you mean as unit is dead without charger in, but I've tried it whilst pressing the foot pedal and with the on off switch set to on, and it makes no difference the unit remains dead

 

[dabomb3k]

I'm starting to think the problem could be with that little pcb inside that is doing all the switching but not sure how I can "prove" this..
I unugged the red and black connector from them and linked them together but the overload i coked in so I unugged it before it done any damage (then tested unit again with the charger in to make sure it still worked)

 

[JohnW2]

Across battery 1 + to - I get 6v ... From battery 2 I get the same ... If I do + to - across battery 1 to 2 I get 12v on the side that goes off into the bike ... If I do the same across the other end which is just a looped bit of cable I get 0 volts (may have to check picture to understand what I mean ) ... As for checking with motor on Im not sure what you mean as unit is dead without charger in, but I've tried it whilst pressing the foot pedal and with the on off switch set to on, and it makes no difference the unit remains dead

What I was asking was whether the voltages you were measuring remained unchanged if you went through the motions of trying to make the motor run (even though it wouldn't run, because it was 'dead'). Are you saying that you did that, and the voltage remained unchanged (i.e. 12V across the pair of battery terminals which 'go to the bike'), even when you 'tried' to make the motor come on?

Kind Regards, John

 

[dabomb3k]

Yea regardless of what I press or don't press, or even if I disconnect the leads and just check the terminals of the battery's I still get 12v (6v each batt)

I've tested the voltage up to the (vcc) part of the little pcb ( the connector with the Orange, red, blue white etc on it ) box too and I get 12v at that stage aswell

Untitled

• dabomb3k
• 28 Dec 2014
• 1

Untitled

• dabomb3k
• 28 Dec 2014
• 1

I also get 12v at the red and black connector that comes directly off the battery at that point aswell

(Hope all that makes sense)

 

[dabomb3k]

I've drawn a diagram of how I've chased the wires so far, hope it can be understood, it isn't in wiring diagram form or symbols due to my lack of knowledge in drawing them 😂

Untitled

• dabomb3k
• 29 Dec 2014
• 1

 

[JohnW2]

I've drawn a diagram of how I've chased the wires so far, hope it can be understood, it isn't in wiring diagram form or symbols due to my lack of knowledge in drawing them

Well, what I would now probably do would be as follows:

With charger not plugged in and with the black and yellow joined at the charger socket, confirm that there is about 12V between the left-hand two terminals on the 'PCB' (i.e. coming from battery) and then determine whether there is any voltage between the right-hand two terminals ('to motor') when one attempts to switch the motor on (the 'on-off switch', I imagine).

What does the foot pedal do?

Kind Regards, John

 

[dabomb3k]

With charger not plugged in and with the black and yellow joined at the charger socket, confirm that there is about 12V between the left-hand two terminals on the 'PCB' (i.e. coming from battery) and then determine whether there is any voltage between the right-hand two terminals ('to motor') when one attempts to switch the motor on (the 'on-off switch', I imagine).

What does the foot pedal do?

Kind Regards, John

I am getting 12v going off the pcb to the on/off button.. The on off button is just literally an on/off switch for the whole bike, when it's working normally it's just a big round button that he presses to turn the bike on and off (it lights up when it's on and makes a sound.. All of which works when I switch the black and yellow wire and run it off the mains but doesn't when it's in a standard setup off the battery)

The foot pedal is what you use to run the motor he presses it and depresses it to move or not move.. Again this works when I'm getting a supply direct from mains but doesn't function when it's off the battery

-: I'm starting to wonder if im getting 12volts but the battery's aren't pulling any Ampage , which unfortunately my multimeter cannot check :-

 

[JohnW2]

I am getting 12v going off the pcb to the on/off button.. The on off button is just literally an on/off switch for the whole bike, when it's working normally it's just a big round button that he presses to turn the bike on and off (it lights up when it's on and makes a sound.. All of which works when I switch the black and yellow wire and run it off the mains but doesn't when it's in a standard setup off the battery) ... The foot pedal is what you use to run the motor he presses it and depresses it to move or not move.. Again this works when I'm getting a supply direct from mains but doesn't function when it's off the battery

Fair enough - but if (with charger not connected and yellow and black joined at charger socket), if you switch the switch 'on' and press the pedal, do you get any voltage between the two wires going from the 'PCB' to the motor?

-: I'm starting to wonder if im getting 12volts but the battery's aren't pulling any Ampage , which unfortunately my multimeter cannot check :-

That's why I asked you to check the voltage across the battery when you attempted to make the motor run. If it were a duff battery (or a battery which wasn't getting charged), it might have 12V across it 'off load', but that would fall to a much lower voltage when the motor tried (fairly unsuccessfully!) to draw current (amps) from it. However, you seem to have indicated that this did not happen.

Kind Regards, John