Sakura bike staying on full throttle

[Acker]

Hi All

I wonder if someone might have an answer to the below problem.

I have only just recently got an electric bike and wished I had done it a few years ago. On the strength of this I bought my wile a bike, but today we hit a problem and I was wondering if anyone can help.

my wife came to meet me from work on her Sakura electric bike.

She lost all power, on getting the bike home I checked inside the battery and the 25a fuse had blown.

On replacing this and putting the battery on the bike, turning it on, the bike shot across the garage on full power.

I switched it off lifted the back wheel, turned it back on and the motor Is running at full power, no response to the hand throttle, this is the only way of controlling the power, assumed it is only wired for the hand throttle.

I have checked all the wiring going to a box marked 36Y-18AP, there are no loose wires.

 

[Alan Quay]

I would guess a broken throttle. Often when they fail they send the full throttle signal. It could also be that you accidently connected it the wrong way (just a possibility).

As for the box, I'm guessing its a 36v, 18 Amps Peak controller.

 

[Deleted member 4366]

If it's a brushed motor, you've blown a FET in your controller, so you'll need a new controller. Do you know if it's brushed or brushless? If not, you need to follow the wire from the motor to the controller until you get to a connector. then, count the wires. two wires = brushed; more than two = brushless.

 

[shemozzle999]

The Electric Transport Shop carry spares for your bike, it might be worth having a word with them:

http://www.electricbikesales.co.uk/shop/parts-spares/sakura/cat_191.html

or click on their sidebar advert on the rhs of this page for contact details.

 

[Acker]

Thank you for your replies to my problem

There is a red and black wire from the controller to the motor, so I assume this means brushed and a new controller needed.

If I disconnect the throttle and test to see if the motor runs, would that tell me that the problem is not the throttle but the controller.

 

[Deleted member 4366]

The throttle gives the signal to the controller, and then the controller sends the power to the motor by switching on/off the output FETs very rapidly (PWM). It's very common for the FETs to blow on brushed motor controllers, when the FET/s stay open to deliver full power to the motor, which will blow the fuse.

You can open the controller to check the FETs. They have three legs.The one on the left controls it, and the middle and right are the in and out of the switch. If you measure the resistance between those two legs, it should be very high. If it's low, it's blown.

 

[Acker]

Thanks for all the feed back.

I have the name of a company in Corby who are going to check and repair the throttle or controller.

 

[Martin@e-bikeshop]

Hi Acker,

I understand you called earlier, I was in a meeting, obviously we only work on Crank Drive eBikes. But thanks for calling anyway.

If you dont have success with the guys in Corby, try Bernie at a place called 'Bikes & Batteries'. He will have spare controllers and throttles to hand.

Regards
Martin

 

[Acker]

Hi Martin,

how spooky, that's who I am sending it too.

best regards
Mick