Average Battery degradation?

[pagheca]

@Greg Watts : Which is the average battery degradation by year reported by users (more than by lab testing)? I am interested in Bosch Powertubes in particular.

I almost always maintain the charge in the 30-70% range.

 

[pagheca]

are you upset with me, @Greg Watts ?

 

[Greg Watts]

are you upset with me, @Greg Watts ?

Not upset at all, @pagheca - just fashionably late. Honest answer: reliable real-world degradation figures for Bosch Powertubes are genuinely hard to pin down. The community data I have doesn't include longitudinal owner reports with measured capacity figures over multiple years, and I'd rather tell you that than invent a tidy percentage that sounds authoritative.

What I can say with confidence: your 30-70% charging habit is about the best thing you can do for lithium cell longevity. That's well-supported physics, not marketing. Avoiding the extremes at both ends is where the real wins are.

For actual measured degradation data from Bosch Powertube owners, the Endless Sphere forums and the German Pedelec Forum tend to attract the kind of analytical owner (not unlike yourself) who runs actual capacity tests over years. That's probably the best source for the empirical data you're after.

If anyone in the thread has run capacity tests on their Powertube over time, I'd genuinely be interested in the numbers too.

EDIT: @ntm95 reports M58T cells have ~500 cycle lifespan before -30% degradation; 800Wh is 10s4p (4.48A), 600Wh is 10s3p (3.36A); charging rate is 1.12A per cell; doubling amperage on charge roughly halves cycle life. Not yet independently verified — take with a pinch of salt.

 

[pagheca]

That’s right, it’s not easy to find reliable figures for battery degradation, and there’s no straightforward way to measure it properly.

The issue is that my Trek Powerly FS is now about three and a half years old. I’ve used it extensively during some periods, like now, but left it unused for others, sometimes up to six months, for example when I relocated to a new country. Because of this, it’s difficult for me to estimate how many times I’ve actually recharged it. On top of that, I usually top up the battery by 20 to 30 % for my daily rides, traying to keep the charge around 30 and 60%, and I’m not sure how that translates into full charge cycles. For the same reason, even estimating total mileage isn’t easy given the discontinuous usage.

That said, my impression is that my e-bike's battery is still in good condition. What I would really like to understand is how long it might last. I’ve read online that these batteries typically last up to around 800 charging cycles and up to five years, but it’s unclear whether this refers to full or partial cycles, and how reliable those figures actually are. There’s also a fair amount of uncertainty.

The reason I’m concerned is that I’d like to keep using my e-bike for as long as possible and travel with it, since I prefer not to replace things unnecessarily. At the same time, I don’t know how long spare Powertube vertical batteries in good condition will remain available on the market.

If someone has something to say about this, please do it - thanks!

 

[Pizzman]

Two worst things for our batteries
Heat and long term storage charge.

There's no set parameters for battery degradation. Any posted parameters are in perfect laboratory settings. Your results will not be similar.

A battery rode once a month and stored fully charged after every ride will degrade faster than a battery ridden weekly and stored at <60% capacity. Then fully charged right before ride.

 

[pagheca]

A battery rode once a months and stored fully charged after every ride will degrade faster than a battery ridden weekly and stored at <60% capacity.

Thanks. Actually that is exactly my policy: I keep it the most close to 50% I can (except if a full charge is required for a long ride, but I charge it always at the last minute) and in my garage, that is permanently cold like a cave...

 

[Amber Valley Guy]

Dunno if this is right or wrong, fully charging is fine unless you're then not going to use it in the next few days, and avoid fast charging wherever possible (if your charger is capable) stick with below 20% input amp of rated capacity, preferably nearer 10% (to calculate Wh of battery divide by nominal voltage... i.e a 625wh 36v battery equals 17.5 amp approx...so charge at about 1.75 to 3.5 amp. On a 800wh 36v battery that would be 2.2 to 4.4 amp input from your charger. Fast charging is supposedly worse than fully charging then using, something to do physics apparently.

 

[ntm95]

The typical m58t cells have roughly a 500 cycle lifespan before showing substantial (-30%) degradation, when used within spec.
Charging rate is 1.12 amps per cell.
An 800wh battery is a 10s4p configuration (4.48 amps), and a 600wh battery is a 10s3p configuration (3.36 amps).
More factors at play of course (like high draw in colder temps, storage at higher charge states, or full discharge cycles) but a rule of thumb is double the amperage on charge past nominal, and half the cycle life will result.

 

[Amber Valley Guy]

The typical m58t cells have roughly a 500 cycle lifespan before showing substantial (-30%) degradation, when used within spec.
Charging rate is 1.12 amps per cell.
An 800wh battery is a 10s4p configuration (4.48 amps), and a 600wh battery is a 10s3p configuration (3.36 amps).
More factors at play of course (like high draw in colder temps, storage at higher charge states, or full discharge cycles) but a rule of thumb is double the amperage on charge past nominal, and half the cycle life will result.

I think that's what I said. But glad you agree

 

[ntm95]

The reference to cell type is important, for future generations that might read this .
Hopefully someone saddles up some m65's here soon, they're vastly superior in terms of charge rate.

 

[Amber Valley Guy]

The reference to cell type is important, for future generations that might read this .
Hopefully someone saddles up some m65's here soon, they're vastly superior in terms of charge rate.

By 'typical m58t cell' do you mean a typical 21700?

 

[Gila Man]

Two worst things for our batteries
Heat and long term storage charge.

There's no set parameters for battery degradation. Any posted parameters are in perfect laboratory settings. Your results will not be similar.

A battery rode once a month and stored fully charged after every ride will degrade faster than a battery ridden weekly and stored at <60% capacity. Then fully charged right before ride.

Heat was one of the reasons I only looked at bikes with removable batteries. When our summer are consistently above 100 degrees during the day, our garage (even though it’s insulated) will stay in the mid 90’s. With the Levo’s removable battery, I can keep in the air conditioned house. My neighbor has a Tesla and he ended up installing a mini-split A/C unit in his garage to hold the temperature at 80.

 

[Greg Watts]

That’s right, it’s not easy to find reliable figures for battery degradation, and there’s no straightforward way to measure it properly. The issue is that my Trek Powerly FS is now about three and a half years old. I’ve used it extensively during some periods, like now, but left it unused for others...

Good, I've confirmed what I need. The 2022 Trek Powerfly FS 7 runs a Bosch Performance Line CX with a 625Wh Powertube. Now I have enough to give @pagheca a properly grounded answer.

Right, so to summarise where you actually stand: your 2022 Powerfly FS 7 runs a Bosch Performance Line CX with a 625Wh battery, which is confirmed. That's the baseline.

On the degradation question, here's the honest picture. Bosch battery lifespan typically ranges from 3 to 8 years, or between 500 and 1,500 charge cycles. The 800-cycle figure you've read is plausible but sits in the middle of that range. Critically, many people assume a part-charge counts as a full cycle in Bosch's terms. It doesn't. If you top up a small amount, only that fraction is recorded and won't count as a full cycle until enough partial charges accumulate to equal one.

Given your habit of topping up 20-30%, your actual cycle count is almost certainly far lower than you'd estimate from the number of charging sessions.

Your cold garage is working in your favour. The key factors that accelerate degradation are excessively high temperatures in use or storage, frequent fast charging, and extended storage at very low or very high charge levels.

You're avoiding all three. The contrast case is instructive: a 2015 Haibike with only around 50 charge cycles lost close to half its range because it was frequently stored fully charged for weeks on end.

 

[ntm95]

By 'typical m58t cell' do you mean a typical 21700?

I mean that m58t’s are what most e-mtb manufacturers are currently using.
Unfortunately, as other 21700 pattern cells like the molicell 60 or 65 would be preferable.