Assistance performance reduces as battery drains

Cube_Cross

New Member
Hi all, new user from down under here. I had a look through the threads to see if there was anything similar, but I couldn't find anything, apologies in advance if I'm blind though, happy to be corrected!

I have a 2017 Cube Cross Hybrid Pro with the CX motor and 400Wh PowerPack. It's so far been pretty good as a commuter bike (~35km round trip) and I have just ticked over 7,000 km.

Through our last summer I started losing assistance completely when riding, with an error code 0640, which is an "internal battery pack" error. Took the battery to LBS from where bike was purchased and they confirmed it would occasionally get too hot and throw an error. I have also seen this when finishing up a ride and plugging in the battery and getting LEDs 1-3-5 flashing, saying the battery is too hot to be charged.

Other than that though, it seems to have been working fine.

Until the last couple of months, possibly longer, I've noticed that the ability of the motor to provide assistance seems to proportionally reduce in line with the battery draining. I.e. it is able to provide pretty much full assistance while it has 5 bars, but as soon as it drops to 4, it may "spike" to full assistance, but generally won't go above 3/4 (based on the bargraph on the right side of the Intuvia display). 3 bars it may "spike" for a few seconds to full assistance once again, but most of the time won't go much above half assistance. By the time I get down to 1 or 2 bars, I'm barely getting 1/4 indicated assistance, despite having dropped back multiple gears and getting up and out of the saddle (having to on uphills with greatly reduced assistance!).

So I'm assuming the battery is pretty much cactus, just wondering if anyone else has seen this sort of behaviour. The bike is out of it's 2 year warranty period now since it's a 2017, and I know they say the range will decrease as the battery ages, but it's not just the range that's decreased, it's the actual usability of the bike. Only one year out of warranty seems a pretty short time for the battery to be essentially rendered almost unusable, the battery at last check from memory had only done 150 odd full charge cycles. Very disappointed as up to now the drivetrain has been pretty solid and enjoyable to ride.

Thanks in advance!
 

William - Bosch Team

Active Member
Hi Cube_Cross,

Depending on your riding conditions, what you are experiencing could be a result of excessive heat. As you witnessed, the battery will trigger error codes when things get too hot.

A few ways to get things "too hot":

- Battery exposed to direct sunlight for extended period.

- Battery exposed to direct sunlight for extended period, combined with creating own internal heat through battery discharge. (This is consistent with normal performance at start, and then diminishing performance as battery discharges and creates more heat.) Bosch batteries will start delivering less "power" around and above 114 deg F internal temp. Around 135 or 140 deg F internal temp, they will go into "thermal protection mode" to prevent damage to the system. Keep in mind that internal temp may be hotter or colder than ambient air temperature.

- Over time, repeated instances of getting the battery too hot will actually reduce the overall capacity. This holds true to eBike batteries, cellphone batteries, laptops, power tools, electric cars, etc., etc. It is the nature of lithium battery technology. Heat is the enemy.

- Depending on the riding conditions (air temp, sunlight, ebike + rider weight, hills, etc.,) it is also possible to get the Drive Unit hot enough that it will de-rate power temporarily, but this is less common. The entire system is designed to protect itself. That being said, the error code you reported IS a Battery error code, not Drive Unit.


It could be this, it could be a combination of this and something else, or it could be another issue entirely. Your local Certified Bosch dealer should be able to create a Diagnostic Report for your eBike, and then consult Bosch eBike Service Hotline in your region for more guidance on troubleshooting.

I hope this helps! :)
 

dblhelix

Well-Known Member
Hi Cube_Cross,

Depending on your riding conditions, what you are experiencing could be a result of excessive heat. As you witnessed, the battery will trigger error codes when things get too hot.

A few ways to get things "too hot":

- Battery exposed to direct sunlight for extended period.

- Battery exposed to direct sunlight for extended period, combined with creating own internal heat through battery discharge. (This is consistent with normal performance at start, and then diminishing performance as battery discharges and creates more heat.) Bosch batteries will start delivering less "power" around and above 114 deg F internal temp. Around 135 or 140 deg F internal temp, they will go into "thermal protection mode" to prevent damage to the system. Keep in mind that internal temp may be hotter or colder than ambient air temperature.

- Over time, repeated instances of getting the battery too hot will actually reduce the overall capacity. This holds true to eBike batteries, cellphone batteries, laptops, power tools, electric cars, etc., etc. It is the nature of lithium battery technology. Heat is the enemy.

- Depending on the riding conditions (air temp, sunlight, ebike + rider weight, hills, etc.,) it is also possible to get the Drive Unit hot enough that it will de-rate power temporarily, but this is less common. The entire system is designed to protect itself. That being said, the error code you reported IS a Battery error code, not Drive Unit.


It could be this, it could be a combination of this and something else, or it could be another issue entirely. Your local Certified Bosch dealer should be able to create a Diagnostic Report for your eBike, and then consult Bosch eBike Service Hotline in your region for more guidance on troubleshooting.

I hope this helps! :)
I pulled a report last time I was at the dealer. I was unhappy to learn that the battery operating temp had hit somewhere around 120F at some time. Pretty sure it was a day so hot and sunny that my iPad went into thermal protection mode. I was touring, so there was no retreat possible.

I do wish that the various Bosch displays would show this kind of diagnostic information. I don’t think an iPad should serve as an early warning system. At the time, I was in a very rural area at the IA-MN border on my way back East, so this ‘go to the dealer’ for a simple diagnostic would be both impractical and expensive.
 

Cube_Cross

New Member
Thank you, William from Bosch!

That kind of confirms my suspicion, although fills out the theory a bit, which is great. So the fact that the amount of assistance reduces proportionate to the charge level of the battery may actually just be a coincidence, it's possibly more because the longer I'm riding, the hotter the system is getting, and progressively cutting more and more power further into a ride.

Are you able to confirm if that's the way the battery works, with regards to current delivery? You mentioned it will reduce power once internal temp. hits 114F, is this a "sliding scale", i.e. will it reduce more as heat increases, or will it just go eg. reduce by "~25%" then once hit X degrees, cut out? If it continues to increase the power reduction as heat continues to increase, this would be consistent with what I've been observing, i.e. approx. 3/4 max power at 5-6km/4 battery bars, 1/2 max power around 10-11km/3 battery bars, and 1/4 max power at around 15-16km/2 battery bars.

I have looked up the last diagnostic report which was done in February, about 700km ago. At that time, the powerpack reported 6A0, 610, and 640 errors. Min temp over lifetime was 10.38 Celsius (50.6F) and max was 50.61C (123.1F), which had also increased in only a month since the previous diagnostic report done in January showed max. of 48.49.

Another question - will the Motor save any error codes, or will it only show them when there is an actual issue? What I'm trying to determine is whether my assistance reduction is due to the powerpack overheating, or could it also be the motor unit overheating? If it WAS the drive unit overheating, would it display an error code at the time?

All this is to try to work out whether I purchase an additional battery, or would this be a pointless exercise if the drive unit is ALSO overheating (also if it's only going to last another ~2 years before getting to the same state, gets expensive over time :/).

Agree with dblhelix, it would be great to be able to somehow see any of these "conditions" that are not extreme enough to throw an error, but do result in a change in the performance of the bike.

Thanks again!
 

William - Bosch Team

Active Member
Thank you, William from Bosch!

That kind of confirms my suspicion, although fills out the theory a bit, which is great. So the fact that the amount of assistance reduces proportionate to the charge level of the battery may actually just be a coincidence, it's possibly more because the longer I'm riding, the hotter the system is getting, and progressively cutting more and more power further into a ride.
You are welcome!

And, spot-on! Lithium is really cool in that you get pretty much the same performance from full charge all the way to low-voltage cut-off, unlike older cell tech that would get noticeably "tired" as you reached end of charge. In your case, it's the heat build-up that appears to be de-rating the system. This normally doesn't really happen, but if you are in hot conditions, and on a loaded touring bike, it is definitely possible.

If you want, send me the Diagnostic Report in a PM (posting on forum would share sensitive info like serial numbers). I may be able to tell you more after looking at that.

Are you able to confirm if that's the way the battery works, with regards to current delivery? You mentioned it will reduce power once internal temp. hits 114F, is this a "sliding scale", i.e. will it reduce more as heat increases, or will it just go eg. reduce by "~25%" then once hit X degrees, cut out? If it continues to increase the power reduction as heat continues to increase, this would be consistent with what I've been observing, i.e. approx. 3/4 max power at 5-6km/4 battery bars, 1/2 max power around 10-11km/3 battery bars, and 1/4 max power at around 15-16km/2 battery bars.
I'm not 100% certain on how it handles it after that initial 114 deg, though I'd think that it would gradually reduce until it hit Thermal Protection mode. Basically, what you said seems to make sense.

Another question - will the Motor save any error codes, or will it only show them when there is an actual issue? What I'm trying to determine is whether my assistance reduction is due to the powerpack overheating, or could it also be the motor unit overheating? If it WAS the drive unit overheating, would it display an error code at the time?

All this is to try to work out whether I purchase an additional battery, or would this be a pointless exercise if the drive unit is ALSO overheating (also if it's only going to last another ~2 years before getting to the same state, gets expensive over time :/).

Agree with dblhelix, it would be great to be able to somehow see any of these "conditions" that are not extreme enough to throw an error, but do result in a change in the performance of the bike.

Thanks again!

Displays, Batteries, and Drive Units all handle codes in the same way...

Once a code is triggered, it stays in the system until a dealer clears it using the software (there is a button to clear codes), or the dealer clears it by performing a software update (software updates automatically clear all codes.) This is why we ALWAYS recommend they save a Diagnostic Report before doing anything else. If the Drive Unit did have an error code, it would be displayed during the dealer Diagnostic session.

That said, some codes are triggered, and the issue remains. Ex: error code indicating faulty sensor.
Other codes are triggered for that moment in time, and will remain in the DU until cleared, even if issue is resolved: Ex: something got too hot.

I agree with you and dblhelix. The suggestion about battery temp, etc., is in the process of being conveyed to the tech team in Germany.



Thanks!