How much battery capacity is lost annually?

#boosted

100 mW
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Jan 4, 2021
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On average, how much battery capacity is lost every year with a ebike lithium ion battery? What if its stored properly every year for a few months and kept indoors? How many years can I expect out of it?
 
It all depends on how you treat the battery.
- Depth of discharge, do you use 5Ah of a 15Ah battery or do you use it all.
- Charge rate, 1A charge or 10A charge
- Do you use battery in the cold
- How battery are stored, temperature and voltage
- The biggest aspect is how many amps are you pulling from the battery, say you got a 40A bms on the battery but you got a 20A controller. You aint working the battery hard at all so it will last longer.

#boosted said:
On average, how much battery capacity is lost every year with a ebike lithium ion battery? What if its stored properly every year for a few months and kept indoors? How many years can I expect out of it?
 
markz said:
It all depends on how you treat the battery.
- Depth of discharge, do you use 5Ah of a 15Ah battery or do you use it all.
- Charge rate, 1A charge or 10A charge
- Do you use battery in the cold
- How battery are stored, temperature and voltage
- The biggest aspect is how many amps are you pulling from the battery, say you got a 40A bms on the battery but you got a 20A controller. You aint working the battery hard at all so it will last longer.

#boosted said:
On average, how much battery capacity is lost every year with a ebike lithium ion battery? What if its stored properly every year for a few months and kept indoors? How many years can I expect out of it?

In my case, it's used between the temperatures 45-95f and discharged to around 20% then recharged 100. Kept at 50% charge when in storage 65 degrees f. I use this battery roughly twice a week in the summer, if not more.
 
Most important wear factor is not time, but cycles.
Stored batteries can last very long when the storage is strictly conform to recommendations. In usage, one who is riding a lot of mileage can wear a battery pretty fast, if abusing its specs especially.

Then, battery chemistry and quality are defining the limits that can be expected. Some chemistries are very stable and last very long, others are agressive thus having a very limited life expectation. Trying to stretch a long life out of an agressive chemistry is playing with fire.
 
#boosted said:
markz said:
It all depends on how you treat the battery.
- Depth of discharge, do you use 5Ah of a 15Ah battery or do you use it all.
- Charge rate, 1A charge or 10A charge
- Do you use battery in the cold
- How battery are stored, temperature and voltage
- The biggest aspect is how many amps are you pulling from the battery, say you got a 40A bms on the battery but you got a 20A controller. You aint working the battery hard at all so it will last longer.

#boosted said:
On average, how much battery capacity is lost every year with a ebike lithium ion battery? What if its stored properly every year for a few months and kept indoors? How many years can I expect out of it?

In my case, it's used between the temperatures 45-95f and discharged to around 20% then recharged 100. Kept at 50% charge when in storage 65 degrees f. I use this battery roughly twice a week in the summer, if not more.

There's some really good studies on both cycle life and shelf life for batteries. But they all get muddy when you try to combine the 2. Stored at 40*F at 30% charge with no cycles, a good Lithium battery should only lose about 2% per year. Store it at full charge and that jumps to 5%, keep it at room temp and that jumps to 20%. At 100% depth of discharge, get 300 cycles. At 50%, get 2000. Then you have to consider rate of discharge, etc.

You're never going to get an accurate estimate of life, as there are so many variables, some out of your control like manufacturing quality and defects. Best you can do is look after it the best you can. As a very rough guide:

A battery which is either abused or designed too close to its rated specification (e.g. flat on arrival, or run continuously at more than 2c) will be noticeably degraded in weeks, and won't last a year.

A battery which is used regularly with no special care will probably start losing performance in less than a year, and generally won't make 3.

A well cared for battery (less than 80% depth of discharge, stored properly, slow charged right before use, discharge rate well within spec) won't see much degradation before 3 years, and will probably last 5.

A battery designed for longevity rather than performance (cycled between 20-80% depth of discharge, thermally managed, sub C charge and discharge rates, etc), can easily last 8-10. This is how car manufacturers do it.
 
About two years of use is nearly certain, provided you do store it full for a bms equipped battery. Meaning top it up at least monthly over the winter. Non bms storage is different, store that half full.

My experience is that nobody uses or stores a battery the way NASA would use a battery in a spacecraft. So real world use is much harsher. Often too hot in summer, or too cold in winter, and with a bms, storing it full or nearly full all the time.

After two years, many batteries are still quite usable, but definitely have lost up to 20% of original capacity. At that point you just have to lower the amps you pull from them, and then capacity can surprise you, if the amps are low enough.

And, alas, one bum cell in the hundreds of them in the pack can ruin the whole thing. Not real common, but it does happen.
 
I posted links to research articles on this subject. Should be able to do some work in the search bar to find them. But yep, time x high states of charge x temperature = degradation.
 
I have a 3 year old 14.5ah battery from RAD (nothing special about it), on a bike that's ridden pretty much daily (3-10 miles on average). It's powering a 35a KT controller that's powering a 1000w+ MAC 12t geared hub motor. There is no sign of a loss of range, capacity, or extended charge times to date....
 
Hard 100% dod max amp usage brang Panasonic PF 48V down to 60% after 2 years. Voltage sag is horrible now, 10V on 20A . :roll:

Samsung 35E 52Vafter 2 years of normal usage (80% dod, 70% max amp usage) got it down to 88%. Volta sag still good, 6V on 30 A. :thumb:
 
FWIW, 3 -10 miles daily use is a really good use pattern for longevity. long storage of bms equipped packs problematic. Better to ride it more often for sure. But not 100% discharges so often. That three mile ride just keeps it happy, and 10 miles should be leaving about 25% left when you finish, or more.
 
Battery chemistry makes a difference as well. You have LiFePo4, LiCoO2, LiMn2O4, LiNiMnCoO2, LiNiCoAlO2, Li2TiO3 and others I may have forgotten . Most of the 'Lithium Ion' batteries packs will be LiCoO2 or LiMn2O4. Six years ago I purchased a a Golden Motor LiFePo4 36 volt 12 Ahr battery. I got it for the longevity and I am still using it on my 36 volt bike. My mistake was that I should have gotten the 48 volt version :-(
 
I have a 2015 Ping battery (bought on end of year sale, so probably almost a year older than that) that has lost maybe 25-30% of capacity. It's a 20AH so that isn't a huge deal. It's a very, very good battery. I also try to store it much less than full, in cool temps. I always charge right before riding, not afterwards except for a partial recharge if needed.
 
dogman dan said:
FWIW, 3 -10 miles daily use is a really good use pattern for longevity. long storage of bms equipped packs problematic.

About two years of use is nearly certain, provided you do store it full for a bms equipped battery. Meaning top it up at least monthly over the winter. Non bms storage is different, store that half full.
Why is a FULL charge better than 90%, and recharging as necessary to 90% over the winter months ?
Why not store bms equipped battery just half full and recharge to 3.70V as necessary over winter ?

Is there a Battery University link or article supporting a FULL storage charge (w/BMS) over winter ?
 
I have a battery....

.... that I got out of a junkyard at 5 years old, ran for 3 years about, and still has 100% capacity ( well, more than 100%.. 105% aboot) and I have done nothing but blind charge to 101%, no BMS, store fully charged, used to great DOD, > 70% discharged on average, and charge freexzing, or hot, or wet, or dry... Pushed 8000w peaks, 3.3kW contin, then 10kW peaks, and 4.5kW contin... Smashed them off the ground at speeds of 25-40mph a few times in crashes... Short circuited for >2000A, ran spot welders with it, heated up the garage with it..., Smacked the tire into it, bounced it off the bottom tube, until the bottom tube required welding... because the pack wore out the metal....

It still ran 55mph, and output full capacity, when I replaced it, with a new pack of the same cell, but a newer revision of the cell..... It is LMO-NMC blended.

Wont die. Rode it just about every day for those three years. A few storage events, around 2 weeks here or there. Always stored full. I just didnt care. about " battery care and treatment.. " it amazes me. Recycled EV cells from a Chevrolet. Only rechargable battery I have ever had that just will not die.

Will not die.
 
Battery University is fine for a noob getting up to speed on vocab and basic concepts.

full of errors and overgeneralisations once you start getting into the weeds

You are correct, whether a BMS is connected does not change the fact that low SoC is healthier for storage.

However only if cells are isolated from any potential parasitic vampire loads can you really be confident of your self-discharge rate

which determines your minimum interval for verifying voltage has not dropped below 3.2V or 3V whatever your target floor is.

Some BMS have no significant draw when properly shut down.

Others can completely Murder a pack in just a few weeks, and may do so in an unbalanced way.

Completely isolated, some chemistries have near zero self-discharge even over several years, so your check-topup interval could be 3 months.

So having any circuitry connected can make a huge difference to your storage protocols.


eMark said:
Why is a FULL charge better than 90%, and recharging as necessary to 90% over the winter months ?
Why not store bms equipped battery just half full and recharge to 3.70V as necessary over winter ?

Is there a Battery University link or article supporting a FULL storage charge (w/BMS) over winter ?

 
DogDipstick said:
I have a battery ..... that I got out of a junkyard at 5 years old, ran for 3 years about, and still has 100% capacity ( well, more than 100%.. 105% aboot) and I have done nothing but blind charge to 101%, no BMS, store fully charged, used to great DOD, > 70% discharged on average, and charge freexzing, or hot, or wet, or dry ..... Will not die.
Can imagine U in your element removing the cells from a junk Chevy Volt ... that's reluctant to relinquish them to U.

One of my favorite haunts/hunts (now up in yrs) was removing usable items from U-pull R Parts. Some of which were quite the challenge, but that's at least one-half of the satisfaction when U Win. If it was almost too easy the learning experience wouldn't be near as rewarding ... with final result: Hands filthy dirty; A bruise or two; Proficient enuf so no bloodletting to show for all the unrelenting determination. And much less expensive than a dealership, NAPA, etc.
john61ct said:
Some BMS have no significant draw when properly shut down.

Others can completely Murder a pack in just a few weeks, and may do so in an unbalanced way.
DIY common sense would build it so the BMS is easily accessible when need be: Disconnecting, Checking or Replacing.

A smart DIYer ... one that is smarter than a 'smart' BMS wouldn't need any BMS other than the one between his 2 ears.
 
I have a couple of packs made from Panasonic DA cells that are pushing 10 years old. I haven't done a capacity measurement, but the range I get hasn't changed noticeably and none of the cells have failed.

To get long life, avoid the things that kill batteries. Main thing is not to discharge them completely as much as possible. Most of my rides leave about 50% left at the end. I charge just before riding and charge to about 95%. Excessively high charge and discharge rates kill them fast too. Most likely heat related.
 
Your inquiry and the subesquent replies seem to refer to a battery pack assembly which is made of batteries.
The use of soldered or spot welded connections, I have read, lead to 'dendrites' and unpredictable individual cell aging depending on the individual weld or solder. ( unike Tesla wire bonding )
The best answer to your question that I have read are the test data results here:
Thanks Pajda for more data.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=117028&p=1725214#p1725214
 
dogman dan said:
About two years of use is nearly certain, provided you do store it full for a bms equipped battery. Meaning top it up at least monthly over the winter. Non bms storage is different, store that half full.
No one ever challenged this January 2021 post so many assumed this was good advice/practice to maintaining battery capacity. dogman dan is very knowledgeable -- so why would anyone disagree with full storage SoC with BMS battery?
fechter said:
To get long life, avoid the things that kill batteries. Main thing is not to discharge them completely as much as possible. Most of my rides leave about 50% left at the end. I charge just before riding and charge to about 95%. Excessively high charge and discharge rates kill them fast too. Most likely heat related.
So are you implying when BMS equipped its better to charge to 95% SoC when in storage for a few months? Neither john61ct or DogDipstick disagreed with the above Full SoC recommendation by dogman dan for winter storage with a BMS equipped battery and half full (50% SoC) without a BMS.
Stealth_Chopper said:
The best answer to your question that I have read are the test data results here:
file.php


Pajda's Storage 50% SoC is without a BMS equipped battery. No one has yet too explain why dogman dan has the belief that a Full (or 95%) SoC when battery is equipped with a BMS is preferred rather than a 50% SoC for winter storage.
dogman dan said:
About two years of use is nearly certain, provided you do store it full for a bms equipped battery. Meaning top it up at least monthly over the winter. Non bms storage is different, store that half full.
Is BMSs problematic discharge tendency possibly why dogman dan believes a Full SoC for winter storage and keeping it there when a BMS equipped battery is preferred rather than a 50% SoC ... which is ok when a battery has no BMS ?

Pajda's 50% SoC is without a BMS equipped battery ... same as dogman dan (half full). No one has yet to agree or disagree to a Full SoC for winter storage and "top it up at least monthly over the winter" with BMS equipped battery.
 
Yes, the reason BMS equipped batteries should be stored with a higher state of charge is because the BMS draws power from the pack. That's all. Having a BMS does not change the chemical reactions going on inside the battery.

Ideally, you'd store it with 50% charge and check it often enough that you didn't let it drop down below 30%. But that's not human nature.

I made a $300 pack from high end hoby LiPo just before Covid hit. Charged it to 80%, put it in the garage, a year later it had puffed.
 
eMark said:
dogman dan said:
About two years of use is nearly certain, provided you do store it full for a bms equipped battery. Meaning top it up at least monthly over the winter. Non bms storage is different, store that half full.
No one ever challenged this January 2021 post so many assumed this was good advice/practice to maintaining battery capacity. dogman dan is very knowledgeable -- so why would anyone disagree with full storage SoC with BMS battery?

...

Neither john61ct or DogDipstick disagreed with the above Full SoC recommendation by dogman dan for winter storage with a BMS equipped battery and half full (50% SoC) without a BMS
Yes I did, just now.

I would never let a LI battery sit at high SoC unless the use case required such destructive behaviour.

In which case I'd use LFP if possible, having 10x greater longevity, less impacted by such abuse than li-ion chemistries.

The solution to BMS vampire affect is, either only use BMSs that don't do that, or build the pack so the BMS is easily removed, or design the system to not require a BMS.

eMark, I have requested this many times from you - STOP PUTTING WORDS IN MY MOUTH

Best to not reference others at all, stop playing other members off each other in your little dramas, just state what YOU believe is correct and then accept feedback.

Just because other members allow assertions to stand undisputed, does NOT mean they agree.

 
Sunder said:
Yes, the reason BMS equipped batteries should be stored with a higher state of charge is because the BMS draws power from the pack. That's all. Having a BMS does not change the chemical reactions going on inside the battery.

Ideally, you'd store it with 50% charge and check it often enough that you didn't let it drop down below 30%. But that's not human nature.

Exactly. Forgetfulness and sloth require better system design and component selection.

But combining that with being being knowledgeable, attentive and disciplined, developing a checklisted routine with scheduled reminders is better yet.

Caring for expensive LI packs is a bit like having a puppy not just a piece of inert property you can put away and forget.

IF there is any risk of parasitic loads kicking in.

Fully isolating the cells allows greatly increasing the check-voltage interval time.
 
john61ct said:
But combining that with being being knowledgeable, attentive and disciplined, developing a checklisted routine with scheduled reminders is better yet.

Caring for expensive LI packs is a bit like having a puppy not just a piece of inert property you can put away and forget.

Yes, this is a " special case " for someone like me, a person who has nothing to do but test the cells. Watch like a dog. I dont have a family to get in the way of my time, or hard work, unless it calls.

i test all cells, build, and am diligent and try to not be complacent. I constantly know the SOC of my pack, and use it almost daily year round. I have time to do these things, and make time if I do not. I constantly watch. I am like the old 1960's Dad who takes excellent care of the family car, never letting it get scratched.

....yes, I beat them up, in application, but I check, check, and check again with high quality tools. My balance charger is a very high end powerful charger, probally 1200$ and 5700w, and can datalog 32 cells at once, at 40A. Good datalogs. Before and after data logs. I know a cell well, before I try to build with it. I also ride just about every day.
 
dogman dan (36,386 posts) ... He must be right as no one ever disagreed with his knowledgeable advice as posted ...
dogman dan said:
About two years of use is nearly certain, provided you do store it full for a bms equipped battery. Meaning top it up at least monthly over the winter. Non bms storage is different, store that half full.
eMark only has 842 posts ... Thus believe dogman dan must be correct as no one had disagreed since 1/2021. No one to date has disagreed with his advice of maintaining a full charge for a BMS equipped battery during winter storage. Is his advice actually tongue-in-cheek what not to do ??????

The only other person (as far as i know) that has ever expressed the same as dogman dan is the CEO (Braintrust) of Electric Bike Technologies (maker of Liberty Trike). Both in the LT Instruction Manual, and in an instructional video it's recommended that the BMS equipped 10s5p Li-ion battery be charged full (100% SoC) when storing over winter.

Two very knowledgeable men agree that a BMS equipped battery should be fully charged (100% SoC) for winter storage. Thus, why shouldn't we be assured it's safe to store a BMS equipped li-ion battery at 100% SoC for winter storage ... while only half full (50% SoC) with a no BMS Li-ion battery. Who can explain this 100% vs 50% (ill)logic?

For anyone that may disagree with winter storing of a BMS equipped battery at full 100% SoC here's my suggestion. Remove or disconnect the BMS and store the Li-ion battery half full (50% SoC) as recommended by both dogman dan and Pajda.

In the same post dogman dan seems to contradict previous advice in this last underlined sentence below ...
dogman dan said:
My experience is that nobody uses or stores a battery the way NASA would use a battery in a spacecraft. So real world use is much harsher. Often too hot in summer, or too cold in winter, and with a bms, storing it full or nearly full all the time.
I have sent a PM hoping for clarificaton if he really meant that a BMS equipped Li-ion battery should be fully charged during winter storage. Meaning top it up at least monthly over the winter.

Perhaps what he really means is that even though many ebike novices have been told to do so and are so doing ... that the result of doing so does not improve battery capacity and cycle life ... although preventing battery discharge.
 
Got It, Got It, Got It! ...

Here's where i think Dogman Dan was coming from with both a 100% SoC w/BMS and a 50% SoC wo/BMS for winter storage. It now makes sense :idea: (took a nap to rejuvenate my 78yr gray matter).

  • 1. More than a few have had their Li-ion battery ruined because of what was a faulty BMS ... to the point of some rightly referring to a BMS as a Battery Murdering System. One reason possibly being ...
  • 2. The Charger that comes with a commercial battery isn't adjustable so only way to charge battery is until green light comes on signalling a full (100% SoC), but not good for battery health during winter storage.
  • 3. The vast majority of ebike and escooter owners probably don't have a DMM or if they do they don't want to bother with partial charging (90 to 95%) during their spring, summer and fall rides. Many may not even be aware of the advantage of only charging to 90% for improving battery cycle life longevity.
  • 4. Thus to prevent a faulty BMS from completely discharging the battery during the winter months of storage they've been told or read to give their battery a full charge (100%) before storing over winter. They probably don't even own a DMM so unable to check voltage monthly. Also they may never have thought of plugging in the charger monthly to see if red light comes on indicating a partial discharge.
  • 5. On the other hand batteries that don't have a BMS are most likely a DIY build by a knowledgeable owner with a DMM. An owner that's familiar with the advantage of a 90% SoC for increased cycle life. Also knowledgeable enuf to store their battery (wo/BMS or BMS disconnected) in a cool/dry place just half-full (50% SoC) for wnter storage. Most likely they will also periodically check the p-group voltages over the winter and balance as necessary. Thus doing so (50% SoC) and maintaining it over the winter is better for the health of a Li-ion battery than a 100% SoC over the winter.

When the :idea: invaded my gray matter it also made me feel like a numb skull. If dogman dan does decide to post a followup reply hope he isn't too hard on me for taking so long for his advice to sink in.
 
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