Yamaha System randomly turning off

Hello, I have just purchased my first E-Bike and taken it out. Was cycling up a small hill and the bike randomly cut off without me touching anything. Turned it back on after I noticed it. Carried on cycling and worked for 3m and it done it again. So I thought this can't be right. During my bike ride it turned off about 6 times during 20m. Its a yamaha system with a PW-ST motor and 1.7 display. The dealer is looking into it but they never heard of this issue before. No error codes are displayed and I have tried re inserting the battery to see if its a contact issue and its not. Anyone have any suggestions!

 

Thanks!

if it is new with warranty id take it back to the dealer to sort out as could be anything esp if no error codes are displayed.

if it is new with warranty id take it back to the dealer to sort out as could be anything esp if no error codes are displayed.

Ye they are taking it tomorrow. Just seeing if anyone had any ideas as it could just be a simple fix!

could be just a loose connection but i think you have to drop the motor from the bike to check the wiring harness.

 

if they did a pdi check b4 they sold it they would of found that problem pretty fast but most just dont bother and are box sellers these days.

You could just ask for your money back. If you wait for it to be fixed you’ll be with no bike.

Did they ever locate the issue? Having exactly the same issue with a brand-new Babboe Curve Mountain, which also features the Yamaha PW-ST mid motor - the electronics turn off completely after 20 minutes. The same problem occurs on the replacement bike the vendor gave me, albeit less often, so I’m scratching my head whether this is a problem with a whole batch of batteries?

If there's no error code, it would indicate that the battery switched off or it lost connection. You just have to find out why or how.

If there's no error code, it would indicate that the battery switched off or it lost connection. You just have to find out why or how.

Yep, no error code. Thanks for the pointer!

Or the display unit may not be seated correctly.

and Yamahas have a battery in the LCD. It might be worth checking whether it's gone flat:

 

check the charger voltage as had some faulty ones that was over 42v and was bricking the batts.

check the charger voltage as had some faulty ones that was over 42v and was bricking the batts.

Wow, didn’t think of that… Yamaha? Were the batteries still doing something or did they flat out die?

they was going out of balance and was getting the bms bricked tho i thought they fixed this but it could be something else.

 

cant really do much if you have warranty

they was going out of balance and was getting the bms bricked tho i thought they fixed this but it could be something else.

 

cant really do much if you have warranty

Thanks, I’ll measure the voltage on the charger!

Thanks, I’ll measure the voltage on the charger!

Whatever you do be very careful where you stick your multimeter leads, according to the German forum you can kill your battery if you get it wrong. You would probably also not find the charging voltage without a battery connected as the charger won't switch on until communications are established between the battery and the charger.

Whatever you do be very careful where you stick your multimeter leads, according to the German forum you can kill your battery if you get it wrong. You would probably also not find the charging voltage without a battery connected as the charger won't switch on until communications are established between the battery and the charger.

Aw thanks, that’s beyond my skill set then Thanks for the safety advice!

Whatever you do be very careful where you stick your multimeter leads, according to the German forum you can kill your battery if you get it wrong. You would probably also not find the charging voltage without a battery connected as the charger won't switch on until communications are established between the battery and the charger.

Yup. You can't measure the charger's voltage - the same with your battery. You need to take it to the dealer to check, or do some surgery.

I have done some surgery and run a 385Wh extender battery. Only connect when battery voltage is v close (straight off the chargers is within 0.1v) and Yamaha battery is switched on.

Hello, I have just purchased my first E-Bike and taken it out. Was cycling up a small hill and the bike randomly cut off without me touching anything. Turned it back on after I noticed it. Carried on cycling and worked for 3m and it done it again. So I thought this can't be right. During my bike ride it turned off about 6 times during 20m. Its a yamaha system with a PW-ST motor and 1.7 display. The dealer is looking into it but they never heard of this issue before. No error codes are displayed and I have tried re inserting the battery to see if its a contact issue and its not. Anyone have any suggestions!

 

Thanks!

Hi Dean 142. I'm new to the forum, and I have a new ebike with the same problem as yours. What was the final outcome? Did they fix it under warranty? Regards.

Hello, did anyone who had this problem in this topic, can you please tell what whas the problem and how it was fixed. Few weeks ago i got me a Wheeler IPrime with Yamaha PW ST and after first 3km motor start shut down. Plus i noticed that every time it shut down its reset trip and total km. I ride already around 20km on it but its still shows 3km trip and total 2.8km.

So dfid anyone can tell what was the issue.??

Will drive my bike back to shop next week to be repaired but just wondering how other solve this issue. motor replacement, connection problem, or just money back as this issue not fixable.

That sounds like the battery in the display to me.

I have a Haibike with a Yamaha system, twice it cut out going up a long hill. When I took it fior it's after sales check over they said it was the battery disconnecting which caused it .

I noticed the battery which sits in the frame did not push fully up to the connector at the top so I loosened the screws holding the locking mechanism at the bottom of the battery, then pushed the battery fully up onto the connector using a plastic lever, then I adjusted the locking mechanism up slightly so it now sits fully engaged on the top connector.

Had to play around adjusting it until i could get the battery in and out without too much hassle but it seems OK now.

Don't know if this helps others but worth a look.

I have a Haibike with a Yamaha system, twice it cut out going up a long hill. When I took it fior it's after sales check over they said it was the battery disconnecting which caused it .

I noticed the battery which sits in the frame did not push fully up to the connector at the top so I loosened the screws holding the locking mechanism at the bottom of the battery, then pushed the battery fully up onto the connector using a plastic lever, then I adjusted the locking mechanism up slightly so it now sits fully engaged on the top connector.

Had to play around adjusting it until i could get the battery in and out without too much hassle but it seems OK now.

Don't know if this helps others but worth a look.

That wouldn't cause the milage resets.

That wouldn't cause the milage resets.

That what i was thinking as well. As the Speed counter working ok all the time and mileage and trip counter work till shut down and then its resets to 3km and as well put assist to the High.

Honestly it so annoying to buy a new bike from shop in 2025 and then end up with some issue which is apparently known from 2020:mad:

One thing when motor shut riding down hill and you can switch back on when you down, but its another story when it shut while you ride up hill and there the car behind you. as its still takes like around 5 sec to turn it on back and its start assist to the pedals.

So... finally after 3 weeks of repaire i got my bike back... Merchant told me that this issue known by Yamaha and only way to fix it this issue ... it's replace the motor. Soo my motor was replaced by warranty and i got my bike back.