Shimano EP8 stops working while riding - no fault in log?

[hctagalong]

Well how’s it going lads any joy in recent weeks? I run a guiding business and now have 2 in the fleet with this problem

I've finally connected with a helpful Canyon technical support rep (I'm in the US) and he has been working with Shimano via the warranty claim process. Shimano thinks the problem is the battery+wiring harness (the wire that runs direct from the drive unit to the battery) and are sending me replacements under warranty.

To be honest, I'm skeptical that this is the culprit, but what do I know -- I'm a rookie with regard to eMTBs. Further, I've already tested with a different battery and it was fine for a few rides then the dreaded power cut happened. I've reviewed my ride data and have the following observations:

• Problem always happens when the temp is 70+ (Fahrenheit); relative humidity doesn't seem to matter
• Never has cut out at the beginning of a ride; always 1+ hr into the ride. I usually start my rides at 100% battery therefore the battery consumption is around +/- 60% when it happens (not the same each time and one time the consumption was only around 45%; an outlier but was fairly warm that day)
• Only occurs at trails and outings when I'm riding a bit more "spirited" (constant motion, pushing the pace, rougher terrain). Ride a little lighter pace with some stops along the way, no power cut.

Given the above this seems like a thermal problem to me but again, Shimano believes it's a battery+wiring harness. I haven't received those yet but should early this week. I'll get them on straight away and try again. The challenge is that it's getting cooler where I live now that summer is winding down and I've not experienced a problem, yet, with cooler temps (I got the bike September 2023 and didn't have any problems until June 2024). For reference, I now have just over 500 miles on it.

I'll let you know what I find after I get a few rides in with the new wiring harness and battery.

 

[Enduromalagaemtbholidays]

Well....bummer. New battery is not the answer. Another ride (using the alternate battery) and unfortunately additional power cut-outs. Again, no faults in the drive unit logs. And, like the other events, it doesn't occur until later in a ride (60%+ of the battery consumed). Only guess I have left is that it's a thermal-related problem.

At this point I have nothing left to try except keep working the warranty process (which has its own challenges that I'm learning about).

Well how’s it going lads any joy in recent weeks? I run a guiding business and now have 2 in the fleet with this problem

I've finally connected with a helpful Canyon technical support rep (I'm in the US) and he has been working with Shimano via the warranty claim process. Shimano thinks the problem is the battery+wiring harness (the wire that runs direct from the drive unit to the battery) and are sending me replacements under warranty.

To be honest, I'm skeptical that this is the culprit, but what do I know -- I'm a rookie with regard to eMTBs. Further, I've already tested with a different battery and it was fine for a few rides then the dreaded power cut happened. I've reviewed my ride data and have the following observations:

• Problem always happens when the temp is 70+ (Fahrenheit); relative humidity doesn't seem to matter
• Never has cut out at the beginning of a ride; always 1+ hr into the ride. I usually start my rides at 100% battery therefore the battery consumption is around +/- 60% when it happens (not the same each time and one time the consumption was only around 45%; an outlier but was fairly warm that day)
• Only occurs at trails and outings when I'm riding a bit more "spirited" (constant motion, pushing the pace, rougher terrain). Ride a little lighter pace with some stops along the way, no power cut.

Given the above this seems like a thermal problem to me but again, Shimano believes it's a battery+wiring harness. I haven't received those yet but should early this week. I'll get them on straight away and try again. The challenge is that it's getting cooler where I live now that summer is winding down and I've not experienced a problem, yet, with cooler temps (I got the bike September 2023 and didn't have any problems until June 2024). For reference, I now have just over 500 miles on it.

I'll let you know what I find after I get a few rides in with the new wiring harness and battery.

this is the best narrowing down of this problem I’ve seen on the internet

Ok so, I have one bike (Husqvarna mc4 23) , I believe it’s likely the wiring harness one really brutal day of dh runs on the “sram test track” in mijas Spain (next bike could be thermal ) started out with a silent bike but could hear the battery slowly rattle its loose inside the carbon frame and problems started but manageable also aggravated by the hot Spanish summer 40+ Celsius, Every man, beast and machine is suffering lol

The Other bike a husky mc2 with ep6 motor doing the same when it gets warm cuts of sometimes even on smooth roads, no error log but definitely heat related. I’m noticing across the bikes that if it gets hot enough that it won’t turn back on any given ride from then on it cuts out after roughly 50% battery usage or a good hours worth of abuse, but I haven’t found any info on heat sensors or anything like that yet.

@hctagalong if you ever escaped the winter to southern Europe you deserve a complementary emtb tour some day for that quality of detail in your e-bike experience

 

[Borbea]

I had this on my Husky. It was bad connection between the battery and connection plate in bottom of battery compartment.
Remove the battery unscrew the plate (battery connection) in bottom of battery compartment. Spray some WD40 and dry. Assemble all back.
Also check the power button.

 

[hctagalong]

Minor update:

I received the warrantied wiring harness and battery from Shimano (via Canyon) and haven't had a cutout since replacing both. While I'm near positive that the battery wasn't the problem (recall that I had tried a second one from the original and still had cutouts -- I'm skeptical that 2 batteries would be defective) perhaps it actually was the wiring harness .

When I replaced the wiring harness, there was no apparent damage to the original one; no cuts, kinks or worn through casing. Nothing of note. Both ends of the connection look normal as well -- on the Spectral:ON the wiring harness is simply a cable that connects to the drive unit and battery directly with no fixed plate/retainer/etc.

Is my saga over? I'm hopeful but not totally convinced. I have ~ 100miles on the new battery+wiring harness but none of that was in hot weather or as spirited riding as when I've experienced the cutouts. Now that temps are falling in my area, I doubt I'll see this again until next season if I do at all.

I appreciate the support and suggestions. Should any of you have cutouts, I feel for you and hope you get it sorted out quickly. Shimano is confident that this will address it for me, time will tell.

 

[steve_sordy]

I had an intermittent power loss problem.
Long story short, it turned out that when a new battery was fitted under warranty, they pinched one of the cables going to the display. That was all it took. There was no external sign of damage. The cable cost £7, but getting to it was a problem (on a Focus Jam2 and not designed to come out as a matter of course) and therefore expensive. thankfully it was still under warranty.

 

[Trickfox]

Figured I'd add my story as another data point. Bought a 2023 Canyon Spectral:On with EP801 & 720 battery in May. Experienced the random cutoff issue starting in June. Did a warranty claim with Canyon through an LBS. At first they were going to send a new harness to the LBS, then decided they thought it was the motor. Shimano provided a replacement motor. About a month on the new motor, and the issue started again.
I've mostly ridden in hot weather, so my first assumption was heat. But I've had 100F rides with no issue, and 80F rides with cutouts in the first 10 minutes, before the motor could have gotten too hot.
I usually experience only one or two cutouts over the course of a 15 mile, 2 hour ride. Sometimes I can do a big ride with zero cutouts, and other times I've gotten three on an 8 mile loop.
It also doesn't seem to be related to battery level, vibrations or big hits.
It has never happened while pedaling, only when coasting.
My LBS did say they've heard of the issue and have heard it's a problem with Shimano motors paired to non-Shimano brand batteries. Curious if anyone with a Shimano battery has had the problem.
It's such a mild annoyance, and seems to not have a known fix, so I'm putting off starting another claim. Will keep my eyes on this thread, hoping a solution is found some day.