Normal Battery Charge Reduction when "Parked up"?

[SCZ4]

I'm new to ebikes and wondering if it's normal for the battery to drop from 4 bars to 2 in just over a week? Garage is only around 4 degrees, but still surprised by this. The bike is only 4 months old (albeit a 2024 model) and gone through maybe 10 charge cycles.

It's a Cannondale Moterra SL2.

 

[pagheca]

no, it's not normal in my experience. The battery of my emtb loose no more than 1% in a week, at similar temperatures.

I am afraid omething is wrong with your bycicle (or with your battery), bro.

Are you sure there are no services left on? Something like a light, or the monitor. I suggest you to detach the battery from the bicycle if possible, put it at home, and see if it discharges too so quickly. If it doesn't, there is something wrong with the bycicle.

 

[SCZ4]

no, it's not normal in my experience. The battery of my emtb loose no more than 1% in a week, at similar temperatures.

I am afraid omething is wrong with your bycicle (or with your battery), bro.

Are you sure there are no services left on? Something like a light, or the monitor. I suggest you to detach the battery from the bicycle if possible, put it at home, and see if it discharges too so quickly. If it doesn't, there is something wrong with the bycicle.

Thanks, I didn't think it was right.

No lights or accessories connected.

I'll keep a close eye on it and will start documenting it for a warranty claim which could be tricky I think.

 

[steve_sordy]

Battery charge losses while parked up is not something I ever noticed or even thought to measure.
Shimano EP8 system.

 

[irie]

I know nothing about the Cannondale Moterra SL2, but if it's connected to your phone make sure it's disconnected when not being used.

 

[Fredw90]

My SL2 has been parked for 2 weeks and the battery is holding solid. It’s kept in my basement at 68*F.

 

[SCZ4]

Thanks all, definitely sounds like I have a faulty battery.

Not sure how to deal with it as my nearest Cannondale dealer is 100 miles away. It's an Shimano EP8 motor so could technically take it to any Shimano service centre, however they have a Darfon battery, so not sure how that will work.

 

[pagheca]

actually, you could have a fault electronics if you haven't (or can't because embedded) checked the battery while it is disconneted from the ebike.

In any case I strongly advice to remove and store it (or the ebike) somewhere safe, because it could warm up. That power must be dissipated somewhere... The situation could worsen.

 

[SCZ4]

actually, you could have a fault electronics if you haven't (or can't because embedded) checked the battery while it is disconneted from the ebike.

In any case I strongly advice to remove and store it (or the ebike) somewhere safe, because it could warm up. That power must be dissipated somewhere... The situation could worsen.

Thanks, unfortunately I can't remove it easily (motor out I suspect).

I have contacted Darfon.

 

[SCZ4]

Interestingly I noticed in the Shimano app last night the battery is showing "warranty service", but unsure what that means.

 

[pagheca]

be careful. Damaged batteries have an inner risk of "thermal runaway."

 

[SCZ4]

Booked in to my local Shimano repair shop, will report back next week.

 

[Fredw90]

Just out of curiosity what does your charge port cover look like?

 

[SCZ4]

Just out of curiosity what does your charge port cover look like?

It's a rubber flap. Why?!

 

[Fredw90]

It's a rubber flap. Why?!

I bought my SL2 this year (2025 model) only about 300 miles so far mostly in trail mode. No issues.

LBS shop owner has a 24 and just had his motor and battery replaced as it was cutting out on him randomly.

Only visible difference between the two that I’ve been able to tell is the darn charge port cover. Is yours a square cap? Just satisfying my curiosity by asking.

 

[SCZ4]

I bought my SL2 this year (2025 model) only about 300 miles so far mostly in trail mode. No issues.

LBS shop owner has a 24 and just had his motor and battery replaced as it was cutting out on him randomly.

Only visible difference between the two that I’ve been able to tell is the darn charge port cover. Is yours a square cap? Just satisfying my curiosity by asking.

Yeah it is square,.not the best design. What does the 2025 look like?

 

[steveL]

4 degrees is likely well outside the recommended storage temperature.

 

[SCZ4]

4 degrees is likely well outside the recommended storage temperature.

Don't disagree, but still shouldn't be losing 1 bar in 4 days. My car battery and other battery operated items don't lose 20% power in the same time. Also got a E914 error today. Great.

 

[irie]

Don't disagree, but still shouldn't be losing 1 bar in 4 days. My car battery and other battery operated items don't lose 20% power in the same time. Also got a E914 error today. Great.

Saw this:

Cannondale Moterra SL Owners Club | Hi everyone | Facebook

Hi everyone I have a Cannondale Moterra SL2. The problem with error code E914 seems to be related to the power plug for the Shimano EP801 drivetrain. I wedged a relatively stiff piece of micro-rubber...

share.google

 

[SCZ4]

Saw this:

Cannondale Moterra SL Owners Club | Hi everyone | Facebook

Hi everyone I have a Cannondale Moterra SL2. The problem with error code E914 seems to be related to the power plug for the Shimano EP801 drivetrain. I wedged a relatively stiff piece of micro-rubber...

share.google

More E914 warnings today. Thanks for the above link, I had a look today, but impossible to see or get to the connector on the motor without removing it which I don't fancy doing. Will take it to the bike shop later this week.

 

[SCZ4]

Just to close this topic out (hopefully) in case anyone else has a similar issue.

Local Shimano service centre diagnosed a faulty (Darfon) battery and was replaced under warranty. Shimano don't cover the labour, but the place I bought it from have agreed to refund me which I'm happy with.

Will see how it goes. If I don't update then assume all is good.

 

[Bontee]

Battery charge losses while parked up is not something I ever noticed or even thought to measure.
Shimano EP8 system.

Agreed Steve, due to an injury my ep8 with 630 battery sat for over 3 months in the garage and held 60% for all that time, that’s on a 4 year old battery