E-bike stops power shortly - hints for repair requested

[SimonMikkelsen]

In the latest months, my e-bike has started to cut power for roughly 0.3-0.5 seconds when I ride. The shortest cuts can just be felt as a short stop of help from the motor while the longer can be seen as an actual power cut in the display. The cuts feel exactly like, if I stop pedaling for at very short while and starts again. For that reason I'm thinking about the sensor that tells the bike I'm turning the pedals.

No bike shop will touch the bike, because they are not certified (see below) so I have to fix it myself. Any hint to what I should start take apart, look for etc? Any online guides or just guesses at what part could be bad. I have tried searching for the sensor types the bike could use, but I have not been able to pinpoint a specific type. I do basic mechanical bike repairs regularly and has a good understanding of electronics and computers in general. But I have never worked on the electrical parts of an e-bike before.

The bike is a standard front wheel hub motor bike from 2018: I set it to power level 1-9 and when I turn the pedals it will help with this power and fade it out at 25 km/h. It is a Brinckers Brooklyn F7.
Brinckers was only sold and serviced in Denmark by a shop named Hellorider, which closed a couple of years ago. Because no one else are certified in Brinckers nor can get parts, I cannot get any bike mechanic to look at the electrical parts. Actually a lot of independant shops were service partners, but they cannot get parts and will not touch the bike. Brinckers are big in Holland, but does not want to help in any way.

 

[Benjahmin]

We're going to need some photo's.
The motor and any markings on it.
The pedal sensor/bottom bracket area.
The disp[ay.
If you can locate it, the controller and plugs.
First, check the motor plug (should be within 100mm or so of the motor)see that it is fully pushed home. There will be a line indicating when it is so. Is there any sign of heat damage in this area, swollen or crispy cable?
Check the pas sensor. If it is the disc and detector type, then the disc needs to run within 1-3mm of the sensor and run parallel. If it is wobbly or loose this can cause intermittant power cut.

 

[Nealh]

More then likely if a generic pedal sensor is used , then the fault may be just an insatllation fault of said pedal sensor. We need to see some pics of the sensor .

If the sensor arrangement is a generic magnet disc and sensor , then make sure the disc is held firm in place and can't move unless the crank is rotated also check the disc gap to the sensor head is tiny 1mm approx.

 

[saneagle]

This problem has been reported before. Possibly, the battery is not strong enough. Does it only cut out with the power setting set to "Power" or does it do it also when set to "Normal". If the "normal" setting solves it, the battery is the problem. If it doesn't solve it, then you need to look at the pedal sensor.

You can fit any 36v battery you want that you can buy from Ebay, Amazon or Aliexpress if you need one. It would probably best to get another one with the compartment at the front, where the controller sits.

 

[SimonMikkelsen]

Hi
I have attached a few images but a more comprehensive set (including the motor) is in the album https://www.jottacloud.com/share/oou9uah6pkjq

I am guessing this cable could go to the PAS sensor, as you see the pedal crank is attached to the bike. By just looking at it I have no idea how to disassemble it. I have not tried to take off the pedal crank, but that is my only guess.


The connection to the motor:


The display:

The display looks a lot like the one on Das Kit. There is material that states, that when using a lot of these displays, you can press + and - for some seconds, enter a code and get into the settings menu. On this bike I can press SET for some seconds and get directly into the menu. However, I cannot set the speed at which the motor stops helping. The motor will start fading out at 25 km/h and I can set a speed it will fade to. Setting it to infinite lets me get about 50% at 27 km/h and 25% at 29 km/h.

I think it is safe to say, that Brinckers does not make their own parts but have everything assembled in China or the East. Except the tail light, because that is made in Europe and (this is a guess) to not have to ship them to China they get the batteries without a tail light (the whole for the tail light cable is glued shut) and put a tail lights with AA batteries on in Europe. Except for the battery the bike has worked fine despite heavy use in all kinds of danish weather.

Regarding powerlevel, I have it set to power, but the issue will show even at a low power level, e.g. when I follow the kids to school up a steep hill. It seems to happen more often when I turn the pedals slowly, but it still happens when I turn them fast.

1½ year ago I got my battery renovated at at place that promises to use high quality batteries. They could fit 20 Ah into the case, where the original only came with 10 Ah. It is also correspondingly heavier and have a corresponding longer range. So my starting point is that the battery is ok.

 

[saneagle]

If the problem happens at all power levels in all circumstances, it is almost certainly the pedal sensor.

Remove the left side pedal arm with a crank extractor, then you can pull the sensor arrangement outwards and off the bike. There is an inner part that turns with the pedal shaft, and it's connected by friction. The outer part is stationary and held by the shape off the bottom bracket. There two halves are clipped together, so you can prise them apart to check them.

The two problems you get are: 1. Dirt inside that stops the moving part that then causes the second problem. Fix it by cleaning; 2. Dirt wears the moving part so there is insufficient friction to keep it turning. Fix it by adding some adhesive tape to the shaft to make it tighter and clean the inside.
Crank Arm Puller Removal Tool Bicycle Extractor Cycle Crank Wrench Spanner | eBay

The pedal sensor is very cheap ($2 to 5$). You can buy a new one from Ebay, Aliexpress or Amazon.

There are diffeent versions of the C600 display. Some have locked settings. You can buy an unlocked one from Aliexpress.
Bigstone Intelligentlcd C600 Display Electric Bike Instrument Monitor E-bike Speeder Replacement Parts Panel Bafang Led Tft Kit - Electric Bicycle Accessories - AliExpress

If it were my bike, I would change the motor controller, pedal sensor and LCD to Kunteng (KT), which is easier to use and has better speed and power options rather than spend any money on other parts if you need to replace anything.

 

[SimonMikkelsen]

Remove the left side pedal arm with a crank extractor, then you can pull the sensor arrangement outwards and off the bike.

...

Thank you very much. I will try to take it apart the next time I have the time. Probably a weekend. I will post the result of my findings. I also like the suggestion about replacing the controller etc. with something better and unlocked.

 

[AntonyC]

the issue will show even at a low power level, e.g. when I follow the kids to school up a steep hill. It seems to happen more often when I turn the pedals slowly, but it still happens when I turn them fast.

1½ year ago I got my battery renovated at at place that promises to use high quality batteries. They could fit 20 Ah into the case, where the original only came with 10 Ah. It is also correspondingly heavier and have a corresponding longer range. So my starting point is that the battery is ok.

Your pictured items look OK and battery perforance deteriorates more gradually than other components. As Saneagle said capacity declines but also the current they can give, which you'd notice as coping with less steep gradients than before and for a shorter distance uphills even when fully charged (due to Rint). Your school run is a good example, low power but still high current.

First off see how it goes limited to a lower assist level and fully charged every trip, if it's reliable that confirms the other parts are probably OK without getting your spanners out. Cells have their compromises and doubling the capacity in the same space can reduce current capability, making your battery a good tourer but less of a climber.

 

[SimonMikkelsen]

Thanks for all the advise: This is a writeup of what I ended up doing. I would have taken a couple of additional images and drawn on those I got, but as I have been constrained on time this is what I ended up getting out, as advise and inspiration to people who may want to do this on their own Brinckers bike.

By writing to Brinckers they provided me with 2 addresses of companies in Denmark from which I could get technical support and spare parts. One would come to my town and fix the bike and the other could only sell parts. Well, the ones that would fix it never returned with a date, despite e-mails and phone calls so I ended up doing it myself.

Buying from outside of EU is not really and option, as I in Denmark must pay import tax and VAT of even the cheapest goods. The expensive part is the fee I have to pay for paying tax and VAT.

So I ended up getting the official sensor from Brinckers.

The new sensor is not an exact copy of the old one: They seem to have fixed some of the issues they had with the old one. Most importantly: The sensor and the disc with magnets were only held together with friction on the bike, which was not enough, so Brinckers had added 2 O-rings to push them together. A real hacked DIY solution.
The new sensor had 3 small plastic hooks to keep them together. The problem with this is, that the ring with the magnets are held very strongly to the crank shaft with friction, so when I tried to remove it to clean the area better, 2 of them broke off. So I added 2 O-rings to hold it together. The proper way to remove the new sensor is to use a flat screw driver to push it off, not pull in the sensor!


The inner ring with magnets can be seen around the crank shaft. In the top of the shaft you see one of the broken bits that should hold the sensor better together. 1/3 to the left the only non broken one can be seen.
The new sensor also had much tighter tolerances, requiring a very good cleaning in order to get all bits into the proper bits:



Image: All those teeth had to be cleaned a lot more, because there pretty much was an exact fit to the new sensor.


The problem with the old sensor was wear and the tiny tiny magnets that was mostly rusted away. The sensor is made of a plastic disc with magnets that rotates inside the main sensor, which is also plastic. Nothing is neither water nor dirt proof so it will wear out when plastic against plastic is rotating along with water and dirt. A cheap and bad solution.


Pretty worn ring with magnets that are mostly rusted away.


The non moving part of the sensor, also pretty worn but seems to be working fine.

The cable was about 90 cm long, which is longer than necessary, but that was good in my case: The cable runs under the fender, requiring a lot of disassembly to replace it. So I just stripped it to the frame. Less pretty but much easier to replace.


My cabling is not pretty, but I did not have to get the back wheel off, which would require a lot of work (for me at least). You can also spot one of the 2 O-rings I used (as in the original Brinckers solution) between the pedal arm and the sensor.

My plan is to get a sensor or 2 on Amazon.de. They goes for €15 but there is no tax fee. An extra cost is that Brinckers has split the 3 cables from the sensor into 2 different connectors, where all the standard sensors have 3 cables in one. Perhaps to discourage people from buying standard off brand sensors? So I have to get a crimping kit and some connectors to make it work.

Currently I don't have the courage to replace display and controller. What I have works ok and there is a lot of cabling involved in that. With little kids time is also a factor.

Bonus: A shot of the controller, when I had it out. Probably a totally standard thing:

 

[cyclebuddy]

It's good that you came back to the forum to explain what the problem turned out to be, and how you managed to resolve your issue.

It's often quite annoying when (usually new) members post problems and other members here take their time to help with advice and suggestions, and then you never hear from that original poster again. It's a good learning experience for all of us when you take that time to follow-up, so thank you.

 

[Nealh]

The lsw controller is Luishi brand so the PAS is a v12L type and a generic PAS model.