How long do electric bike batteries last? Share your experiences

[Meloyelo]

Hi everyone,

I'm curious about the lifespan of electric bike batteries. As more people switch to e-bikes, understanding battery longevity becomes essential for making informed decisions. I’ve done some research, but I’d love to hear from the community about your experiences.

Key Factors Influencing Battery Lifespan:

1. Battery Type:
   • Most e-bikes use lithium-ion batteries, which generally have a lifespan of 2-5 years.
   • The specific chemistry, such as lithium-polymer vs. lithium-ion, can also affect longevity.
2. Charging Cycles:
   • Battery life is often measured in charge cycles. A cycle is a full charge from 0% to 100%.
   • Typically, e-bike batteries can handle 500-1000 charge cycles before the capacity starts to drop.
3. Maintenance and Care:
   • Proper charging habits, like not overcharging and avoiding full discharges, can extend battery life.
   • Storing the battery in a cool, dry place when not in use also helps.
   • Regularly checking for firmware updates from the manufacturer, as they may optimize battery performance.
4. Riding Conditions:
   • Riding terrain, rider weight, and speed can all impact how hard the battery has to work, affecting its lifespan.
   • Frequent stops and starts, as well as hilly terrain, can drain the battery faster, shortening its overall life.
5. Environmental Factors:
   • Extreme temperatures (both hot and cold) can degrade battery life.
   • If you live in an area with extreme weather, you might need to replace your battery sooner than expected.

Signs That Your Battery Might Be Wearing Out:

• Reduced Range: Noticing that your e-bike doesn’t go as far on a full charge as it used to.
• Slower Charging: If the battery takes longer to reach full charge, it might be aging.
• Voltage Drops: Sudden power drops or inconsistent performance could indicate the battery is nearing the end of its life.

Extending Your Battery’s Life:

• Charge Wisely: Try to keep the battery level between 20%-80% rather than fully charging or fully draining it every time.
• Avoid Extreme Temperatures: Store and charge the battery in a temperature-controlled environment.
• Use It Regularly: Batteries degrade faster when not used for long periods, so try to keep your e-bike in regular use.

What’s Your Experience?

I’d love to hear about your experiences. How long has your e-bike battery lasted, and what tips do you have for extending battery life? Any particular brands or models that you’ve found to be more durable?

Thanks for sharing your insights!

 

[markminnc]

Most of our eBike batteries are fabricated using 3.2v LiFePO4 cells. These cells have similar operating characteristics across mfgs. They are typically rated for 2000-5000 recharge cycles. The actual performance is primarily dependent on the discharge curve and the charge curve. I have a bit of design and use experience of large lithium systems. These systems monitor fairly exact current use and replacement. And under computer control recharge the bank to optimize battery life. Our eBike systems use a much more rudimentary approach. Maybe the best thing we can easily do is limit the possibility of overcharging the battery. The best charge/discharge profile in terms of longevity is to limit discharge to a minimum of Approximately 10% of full charge an to limit charge to 90%. Long term storage should be at 40-60%. Most of us live in the practical and don’t meet these optimum numbers. About the only thing I do with my tool batteries is to disconnect tbe charger at full charge. I just ordered a count down timer which I plan to control the length of time the three chargers are active, (one eBike charger and two tool chargers).

​

 

[Hoggdoc]

Most of our eBike batteries are fabricated using 3.2v LiFePO4 cells. These cells have similar operating characteristics across mfgs. They are typically rated for 2000-5000 recharge cycles. The actual performance is primarily dependent on the discharge curve and the charge curve. I have a bit of design and use experience of large lithium systems. These systems monitor fairly exact current use and replacement. And under computer control recharge the bank to optimize battery life. Our eBike systems use a much more rudimentary approach. Maybe the best thing we can easily do is limit the possibility of overcharging the battery. The best charge/discharge profile in terms of longevity is to limit discharge to a minimum of Approximately 10% of full charge an to limit charge to 90%. Long term storage should be at 40-60%. Most of us live in the practical and don’t meet these optimum numbers. About the only thing I do with my tool batteries is to disconnect tbe charger at full charge. I just ordered a count down timer which I plan to control the length of time the three chargers are active, (one eBike charger and two tool chargers).

​

2000-5000 recharge cycles, seriously? I have never heard or read that before.

 

[markminnc]

2000-5000 recharge cycles, seriously? I have never heard or read that before.

Many published studies on the net. Just google lifeso4 cycle life. Most are very wordy engineering studies. I cut this from one. (Our studies on commercial LiFePO4/graphite cells show that a cycle life of 4320 is achieved at 4C rate with 80% SOC).

 

[m@Robertson]

Most of our eBike batteries are fabricated using 3.2v LiFePO4 cells.

No they aren't. The cells are Li-NMC. The differences between LifePO4 and Li-NMC are significant:

• LiFePO4 lifespan is 2000-5000 cycle life versus 400-800.
• LiFePO4 is safe from fire/explosion. Li-NMC goes boom (I am simplifying EXTREMELY here)
• LiFePO4 is much less energy dense, which is most of the reason it is not used in ebikes. A 20ah LiFePO4 battery is much bigger and heavier than a Li-NMC

LiFePO4 is used in things like home solar battery systems, because the lesser energy density - and hence the increased weight of the packs - is not an issue since the battery is not portable and just sits in the garage. My home solar system has a 12 kwh LiFePO4 battery and it is REALLY big.

That doesn't mean LiFePO4 is never used in ebikes. Its rare and is only used in DIY bikes, but some people can get away with it. @HumanPerson is an admin here and he does it.

BTRPower is probably the only quasi-reliable vendor that does LiFePO4 that I have ever seen. Them are some bigass batteries.

 

[m@Robertson]

The best charge/discharge profile in terms of longevity is to limit discharge to a minimum of Approximately 10% of full charge an to limit charge to 90%. Long term storage should be at 40-60%.

For Li-NMC, if its optimum you are looking for, that number is a lot more like 30 and 80. Everyone knows the 80% number as its quoted so often. The discharge floor is a lot less commonly understood, but is just as bad as letting a pack sit at 100%. There are many sources available to back this up if you do a little looking around. Check Battery University for a good take on Li-ion DoD for a couple of different chemistries. For sure, LiFePO4 is more tolerant of both Depth of Discharge and leaving the battery sitting in a high State Of Charge, so your numbers are better suited to that chemistry... but thats not an ebike battery.

I just ordered a count down timer which I plan to control the length of time the three chargers are active, (one eBike charger and two tool chargers).

I use the basic but reliable BN mechanical timers for ebike chargers, and worked up my own using an Intermatic residential wall timer for my home solar (and my high-ish amp ebike dischargers). The Intermatic units can handle the 15a I am pouring thru when I do a top-up from the grid when we have too many foggy days here.

Ebike Battery Charge Safety: Heavy Duty Cutoff Timer

Add a safety layer to ebike charging practices, with residential/commercial grade components rather than the cheap stuff.

talesontwowheels.com

 

[bigoilbob]

We mostly don't go below 30%, but always fully charge. We don't have a Planet B scenario available for how much better we'd be doing limiting to 80%,. But our 672 and 840 w*h, 54.6 volt nominal, batteries for Bafang 750's - both mid drive with IGH's - have lasted us 6 years and several hundred charge cycles. They live in the basement for the 2-3 months/year when we don't care to use them for our primary means of transport.

 

[addertooth]

If you commute on a bike, range can be important. This often means "oversizing your battery pack" so it can do the round trips (with a safety margin) when only charged to 80 percent. My commute is short, with a typical round-trip distance of 13 miles. The bike only has to run at full speed for about 3/4 mile of the trip to flow with traffic. The rest of the trip I can dawdle at 15 to 35 MPH.

My commuter bike (model not mentioned here by intent) is a dual battery system of a two 63.75 Volt (nominal, 17s) battery packs which provide a combined total of 45 Amp Hour capacity at full charge. There is an option to get up to 75 Amp hour of capacity. I am weighing this carefully at this time. It would be sweet to charge once to 80 percent and do the round-trip to work all week.

 

[Eljimb0]

This thread is a great example of everything you read on the internet it not necessarily true. My e-bike, my lawnmower, my Makita weed whacker, my Tesla powerbank, my sister in laws Tesla car, and my Dewalt chainsaw use 18650 Lithium ion cells in their battery packs. They last a long time years and years.

 

[Successful_Beira]

My friend and I combined weighed 330lbs. With two fully charged batteries, we rode the Emma3 for a total of about 45 miles with a little bit of charge left in the battery, but it wasn't going very fast. That's good enough for me. BTW they used the 21700 battery cell.

 

[JohnnyBeans]

Most of our eBike batteries are fabricated using 3.2v LiFePO4 cells. These cells have similar operating characteristics across mfgs. They are typically rated for 2000-5000 recharge cycles. The actual performance is primarily dependent on the discharge curve and the charge curve. I have a bit of design and use experience of large lithium systems. These systems monitor fairly exact current use and replacement. And under computer control recharge the bank to optimize battery life. Our eBike systems use a much more rudimentary approach. Maybe the best thing we can easily do is limit the possibility of overcharging the battery. The best charge/discharge profile in terms of longevity is to limit discharge to a minimum of Approximately 10% of full charge an to limit charge to 90%. Long term storage should be at 40-60%. Most of us live in the practical and don’t meet these optimum numbers. About the only thing I do with my tool batteries is to disconnect tbe charger at full charge. I just ordered a count down timer which I plan to control the length of time the three chargers are active, (one eBike charger and two tool chargers).

​

Here’s how I do it. If my monitor shows 50% remaining on a 20 amp battery, to me that means I owe the battery 30% or 6 amps to get to 80%. With a 2 amp charger that should take around 3 hours. Maybe I’m an idiot (more like definitely) but I just set the timer on my stove for 3 hours and come back later. This may not be exact science, but seems to be working.

 

[m@Robertson]

This thread is a great example of everything you read on the internet it not necessarily true.

On this subject especially. Vast amounts of hogwash and denial of science via personal anecdote. Not that in this thread. But its a subject that seldom gets an intelligent treatment.

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

My e-bike, my lawnmower, my Makita weed whacker, my Tesla powerbank, my sister in laws Tesla car, and my Dewalt chainsaw use 18650 Lithium ion cells in their battery packs. They last a long time years and years.

Strictly speaking, the 18650's you are talking about are li-NMC. Li-ion is a catchall that covers multiple chemistries.. A LiFePO4 battery is also li-ion.

This is too much detail for most people. The short version is in the Conclusion.

How to make a lithium battery last, or…kill it, if you like.

We have written in the past about tips that will help your expensive lithium battery pack last as long as possible. This article will cover some additional information about what happens inside the…

www.electricbike.com

And some sensible strategy instead of all the graphs and charts:

 

[major masingil]

Here's a good example of signs there is bad series in an ebike battery.

My friend and I purchased the same 17.5ah 52v battery along with a mid drive kit from a reputable business. I got into the changing the motor setpoints and adding customizations to suit my preferences, while my buddy just stuck with setting his throttle to 1 and kept all the other factory motor settings as they were. We ride mostly off-road/logging roads in an area where the hills can get steep. When we rode together I usually ended up with more miles than he did because I would go by myself for short rides. The first time I hit the low voltage cut off we were riding up a steep hill and I was full throttle. My battery voltage at the time was between 50-51v on the display, so it included the voltage sag from my ride. My Low v cutoff was set to 43v. I was reaching the cut off with more than 7 v of usable battery.

When it happened, I assumed I had set the low v cutoff at 46v on accident. When i got it home to check the settings it was at 43v. I also assumed that since I had purchased the battery from a reputable source that it probably wasn't the issue. I assumed the issue was the steep incline on the hill I was riding at the time. I rode a bunch more times but mostly finishing before I reached 51-50 v, but anytime I got in that 51 to 50v range by batt would cut off. It usually wouldn't turn back on even after a few minutes.

I used the batt under those conditions for 2 years. I treated the battery well. It was never discharged past 50v and kept it indoors during the winter. Stored between 60% and 80% charge. The next symptom was the battery would not stay fully charged. It dropped 0.04v almost immediately after being charged.

I sent the batt in for testing. It had a bad series, and by this time it was also out of warranty. $900 lessons learned. The lessons being: if you are reaching your low v setpoint with 7 or more usuable volts you probably have an issue with your battery and not voltage sag. Don't assume you couldn't have a defective battery because you purchased from a reputable source. If you have a battery with a bad series you probably won't be able to safely repair it.