Only powers on when I unplug battery and reconnect

[ElonMust]

This problem is driving me nuts! It’s a Chinese e-bike with the battery inside the down tube. If I take the front forks off to access the battery, I can pull it out a bit wait 10 seconds, reconnect and all is good. Bike switches on and everything works as should.
The problem is that when I turn the bike off or it auto shuts off (After 10 minutes) it will not come back on unless the battery is disconnected again. It’s definitely not the battery as when it’s working I get the max mileage out of it. The bike is a Kakuka k70. Any help would be so appreciated.

 

[Bonzo Banana]

Is there any sort of reset procedure in the manual? Maybe one components is flagging up an error which is being reset by disconnecting the battery. Is there a manufacturer web site for this brand? Bought new or secondhand?

 

[AGS]

I had a similar problem to this once where I could only get it to switch on by either uplugging and reconnecting the display or disconnecting and reconnecting the battery.

I bought the bike with this known fault and it was a a nasty little Lishui controller and a weird GoodTimes display that was factory locked.

So I didn’t bother to do much in the way of fault finding and replaced the controller and display with a KT which has been super reliable and gave me the opportunity to configure it properly for a much better ride.

I suspect the fault was inside the display where a pcb mounted component had either failed or gone out of tolerance latching the display off until power was removed and re applied.

The only way to fault find would have been to open the display and work out at least a partial circuit diagram from the pcb layout and then go probing with a multimeter, which really wasn’t worthwhile in my case, because I would still have had a broken display and then I would have to buy whatever component that I thought had failed and try to replace it without destroying the tracks on the pcb using an inappropriate soldering iron.

A direct replacement OEM display would have cost me more to buy than a replacement KT controller and display.

 

[AGS]

Ooh I just looked at your bike and it’s not a cheap bike and is fully integrated, so bolting on an external controller will not be very elegant.

It‘s another prime example of an ebike with built in obsolescence at a premium cost.

A lovely looking bike but not very easy to maintain.

 

[saneagle]

This problem is driving me nuts! It’s a Chinese e-bike with the battery inside the down tube. If I take the front forks off to access the battery, I can pull it out a bit wait 10 seconds, reconnect and all is good. Bike switches on and everything works as should.
The problem is that when I turn the bike off or it auto shuts off (After 10 minutes) it will not come back on unless the battery is disconnected again. It’s definitely not the battery as when it’s working I get the max mileage out of it. The bike is a Kakuka k70. Any help would be so appreciated.

Someone had the same problem (different bike) about 3 or 4 weeks ago. I can't find the thread, and I can't remember if it was solved. Generally, it's a bad connection either inside the battery or somewhere in the path through the battery connector, and through the connector attached to the controller, so check for loose, burnt or damaged connector blades, pins, bullets, etc.

 

[ElonMust]

Is there any sort of reset procedure in the manual? Maybe one components is flagging up an error which is being reset by disconnecting the battery. Is there a manufacturer web site for this brand? Bought new or secondhand?

I unfortunately don't have a manual. The are no triggered error codes on the screen. I can't find the brand online! It's actually not a bad bike TBF

 

[ElonMust]

Someone had the same problem (different bike) about 3 or 4 weeks ago. I can't find the thread, and I can't remember if it was solved. Generally, it's a bad connection either inside the battery or somewhere in the path through the battery connector, and through the connector attached to the controller, so check for loose, burnt or damaged connector blades, pins, bullets, etc.

I've checked all connections but still nothing. I have found that disconecting the display at the handle bars and plugging back in has the same effect as disconecting the battery, so no more having to take the bike apart to use it! Really want to solve it though. So is the problem at the display/on off switch or the controller/battery.

 

[ElonMust]

Ooh I just looked at your bike and it’s not a cheap bike and is fully integrated, so bolting on an external controller will not be very elegant.

It‘s another prime example of an ebike with built in obsolescence at a premium cost.

A lovely looking bike but not very easy to maintain.

Thanks for your nterest in my probem. It's helpedme comfirm my thoughts that it is the display at fault.

 

[AGS]

I think the problem lays within the display if you need to remove the power from the display and reconnect every time in order to power it up.

However I don’t think it’s easy to repair as a diy job unless you have enough expertise with electronics.

It looks like an expensive display and spare parts availability may be problematic.

An inelegant work around would be to split the cable that goes into the display and fit an on/off switch on the power wire, but that would be a bit messy on such a nice bike.

Alternatively you could try to live with unplugging and reconnecting the display connector every time you use the bike. This carries the risk of eventually damaging the connector, especially if you get the rotation wrong one day and bend the pins.

I did this for a while on mine, but I got fed up with it and replaced the controller and display with commonly available parts. But your bike is designed to use integrated components so replacing them all with generics will ruin the look of the bike.

 

[saneagle]

If the problem were the display, it wouldn't work then not work. We need a logical explanation of how that can happen, and there is one that fits, but you need to do a test first to make it completely logical.

Is there any way, you can put a voltmeter across the battery wires while you do one of those cold starts to confirm whether it's the battery that cuts the voltage or something in the LCD?

 

[ElonMust]

I think the problem lays within the display if you need to remove the power from the display and reconnect every time in order to power it up.

However I don’t think it’s easy to repair as a diy job unless you have enough expertise with electronics.

It looks like an expensive display and spare parts availability may be problematic.

An inelegant work around would be to split the cable that goes into the display and fit an on/off switch on the power wire, but that would be a bit messy on such a nice bike.

Alternatively you could try to live with unplugging and reconnecting the display connector every time you use the bike. This carries the risk of eventually damaging the connector, especially if you get the rotation wrong one day and bend the pins.

I did this for a while on mine, but I got fed up with it and replaced the controller and display with commonly available parts. But your bike is designed to use integrated components so replacing them all with generics will ruin the look of the bike.

Yeah, that's kind of where I am so far. The best thing I can think is to fit a latching switch (on the red power wire) under the bars where there's access to the display. Still a hack though.

 

[AGS]

Yep it is a bit of a hack, but I think that will be the lesser of all evils and won’t completely spoil the bike.

 

[ElonMust]

Yep it is a bit of a hack, but I think that will be the lesser of all evils and won’t completely spoil the bike.

Going in!

 

[AGS]

That’s handy. You can make wiring changes without destroying the display cable.

Are you able to measure the voltage on each of those red wires to ground?

One of them may be battery voltage and the other may be low voltage.

You may be able to switch the low voltage line to remove power from the display rather than battery voltage. This would be a safer option if it works.

 

[Woosh]

If the problem were the display, it wouldn't work then not work. We need a logical explanation of how that can happen, and there is one that fits, but you need to do a test first to make it completely logical.

Is there any way, you can put a voltmeter across the battery wires while you do one of those cold starts to confirm whether it's the battery that cuts the voltage or something in the LCD?

One possible cause is the on/off control on the lcd. It is done via the lcd processor. I have come across a similar fault when the on/off button works only one way, the second pressing of the on/off button doesn't work. You have to switch the battery off and on again or unplug and plug in the 5pin lcd connector. The remedy was to replace the lcd.

 

[saneagle]

One possible cause is the on/off control on the lcd. It is done via the lcd processor. I have come across a similar fault when the on/off button works only one way, the second pressing of the on/off button doesn't work. You have to switch the battery off and on again or unplug and plug in the 5pin lcd connector. The remedy was to replace the lcd.

That can be confirmed with the voltage test, but nobody ever wants to do tests for us.

 

[AGS]

I’m thinking an electronic component in the display is not working properly, either out of tolerance or failed completely and is causing an input to the processor to not latch on/off when the switch is turned off.

So the display needs to be completely powered down for the input to reset.

Without a circuit diagram it’s not possible to be sure. And it’s not really practical trying to replace surface mount components inside these things. They are so small it’s extremely difficult to solder them in place without destroying the pcb tracks.

And I have had a search and can’t find anywhere to get a replacement display.

Like I said in my first post. It’s a lovely bike, but it’s so bespoke that if anything goes wrong with the electronics it’s unfixable without main dealer support. And you know what they are like, they will sell them but won’t fix them.

 

[ElonMust]

One possible cause is the on/off control on the lcd. It is done via the lcd processor. I have come across a similar fault when the on/off button works only one way, the second pressing of the on/off button doesn't work. You have to switch the battery off and on again or unplug and plug in the 5pin lcd connector. The remedy was to replace the lcd.

That's interesting. I thought it might be something around that area. Beyond my knowledge though!

 

[ElonMust]

Well I hacked into it. Tomorrow I'll see if I F**ked It up. If it works, hopefully it might aid someone.