How long do batteries last?

[georgefromvt]

My evelo 48 volt 500 watt ebike has over 3000 miles. When should I replace the motor? Ebike still runs well but range isn't what it used to be. Any suggestions? Thanks. \


Sorry guys, typed when I was tired. I meant when should I replace the battery? Thanks and sorry for the confusion.

 

[amberwolf]

My evelo 48 volt 500 watt ebike has over 3000 miles. When should I replace the motor? Ebike still runs well but range isn't what it used to be. Any suggestions? Thanks.

Why would you replace the motor to fix a range problem?

 

[kdog]

As Aw has suggested, your motor is probly not the issue. Unless it's making horrible noises it's probly fine. Very likely that your batteries are starting to degrade. More info like age, climate, chemistry, pack size, controller size, charging/discharging habits etc will give us an idea. But ~5000kms would be aprox when you would see loss of range in your battery in average conditions.
Roughly ( and can vary hugely) depending on how you use/abuse them.
SLA- 100-200 cycles
Lifepo4 1500-2000 cycles
Li-ion 800-1600 cycles
Your battery doesn't just suddenly die, it slowly has less and less capacity which you see as loss of range and power.

 

[e-beach]

+1 and +1 for Amberwolf and Kdog. Range issues generally are that your batteries are beginning to go.

That of course brings up the question; What kind of batteries are you running? And, how long in days have you been running them?

Keep in mind old batteries degrade faster then new batteries.

 

[redilast]

As Aw has suggested, your motor is probly not the issue. Unless it's making horrible noises it's probly fine. Very likely that your batteries are starting to degrade. More info like age, climate, chemistry, pack size, controller size, charging/discharging habits etc will give us an idea. But ~5000kms would be aprox when you would see loss of range in your battery in average conditions.
Roughly ( and can vary hugely) depending on how you use/abuse them.
SLA- 100-200 cycles
Lifepo4 1500-2000 cycles
Li-ion 800-1600 cycles
Your battery doesn't just suddenly die, it slowly has less and less capacity which you see as loss of range and power.

The cycle life highly depends on the cells and the DOD (Depth of discharge), and temperature exposure, C-rate and charge rate.

For example, many power tool cells if used at 100% DOD with 10-20A current draws are only good for about 250 cycles until 70% original capacity.

This cycle life can be greatly increased by decreasing the depth of discharge. Li-ions also do not like spending a lot of time above 4v, especially around 4.20v. Cycle life is roughly doubled by reducing charge voltage to 4.1v, and quadrupled by reducing it to 4v. 3.92v is what the military uses in some Li-ion packs, which is said to provide about 8x the cycle life vs 4.20v charging, while still providing about 65% capacity output.

So it depends on the quality of the cells, and how hard they are drained, but in some cases you could start to notice big capacity drops in just a couple hundred cycles even from decent quality Li-ions.

If you can I would suggest trying to do a capacity test on your battery pack.

 

[dogman dan]

In my warm climate, nothing has lasted me more than 4 years. Everything has lasted at least 2 years before getting seriously sucky, but even cheap RC lipo can still be used up to 4 years.

The last two years though, very low capacity, very high internal resistance. But by adding up enough of them In parallel, you can still get up to 70% capacity if the discharge rate is low enough. Used as they had been, at 2c rate or so, they may have only 50% capacity.

Lifepo4 still hold the record for me, 3.5 years of hard use before it died because I made a mistake and killed the pack.

Lead the worst for me, I killed my first lead battery in 30 days. And I have seen other lead packs killed in less than 6 months.

 

[georgefromvt]

My evelo 48 volt 500 watt ebike has over 3000 miles. When should I replace the motor? Ebike still runs well but range isn't what it used to be. Any suggestions? Thanks.

Why would you replace the motor to fix a range problem?

Sorry guys, typed when I was tired. I meant when should I replace the battery. Thanks and sorry for the confusion.

 

[spinningmagnets]

Start setting money aside for the next battery, but...I would keep using it until it's reduced capacity gets bad enough that I had to pedal more to make the round trip...

Or...it's always good to have two chargers. Maybe get a second one and charge at work to squeeze out a few more months of battery life.

 

[Ykick]

Battery packs never, ever gain capacity over time.

I know there’s tons of discussion, graphs and empirical data about it but the less you discharge in the lower SOC region the less heat and (I assume) damage inflicted to cells. An extra charger can be much cheaper than a new battery pack.

Of course, eventually packs must be replaced but somewhere around 3-4 years, I got my money’s worth and don’t mind a replacement with a little more C rate and pep.

Good older packs can hang around as range extenders, testing or some other duties.

 

[redilast]

Battery packs never, ever gain capacity over time.

Ni-Mh and Ni-Cd that have been left in an idle state can benefit from cycling every now and then and this can greatly increase their capacity... For example a Ni-mh pack that has been idle for 2 years. Charge it up do a capacity test, cycle it a few times and then do another test it will often times have more capacity. But regularly cycled packs and all Li-ions as far as I am aware will never increase in capacity.

 

[Hillhater]

The cycle life highly depends on the cells and the DOD (Depth of discharge), and temperature exposure, C-rate and charge rate.

For example, many power tool cells if used at 100% DOD with 10-20A current draws are only good for about 250 cycles until 70% original capacity.

This cycle life can be greatly increased by decreasing the depth of discharge. Li-ions also do not like spending a lot of time above 4v, especially around 4.20v. Cycle life is roughly doubled by reducing charge voltage to 4.1v, and quadrupled by reducing it to 4v. 3.92v is what the military uses in some Li-ion packs, which is said to provide about 8x the cycle life vs 4.20v charging, while still providing about 65% capacity output.

Yes, many factors affect cell life to varying degrees, but unfortunately the data on which are the most significant is vague , mixed and often inconclusive with respect to various cell chemistries.
In particular the effect of peak charge voltage, 4.0-4.25 volts , etc is historically mentioned as a life killer, but is that actual peak charge voltage or if a cell is maintained at that voltage for some time (how long ?).
But for sure, if your charger only leaves the cells at 4.0v then yes, you are only going to get 65% capacity.....
......or if you think about it , there is another 50+% capacity available if you boost that charge up to 4.2v !

 

[wesnewell]

Replace the battery at signs of damage, or when it no longer has the capacity to get you where you want to go. I've got ~12K miles and almost 4 years on my current rc lipo pack and it still has ~80% capacity.

 

[Ykick]

Battery packs never, ever gain capacity over time.

Ni-Mh and Ni-Cd that have been left in an idle state can benefit from cycling every now and then and this can greatly increase their capacity... For example a Ni-mh pack that has been idle for 2 years. Charge it up do a capacity test, cycle it a few times and then do another test it will often times have more capacity. But regularly cycled packs and all Li-ions as far as I am aware will never increase in capacity.

Yes, I know that from experience with several 10 yr old NiMh 13Ah F cell packs. They’re not a chemistry for storage standby applications.

But, let’s paint the whole picture and mention that what you’re nit-picking about is merely a temporary condition. Once nickel chemistry has been properly cycled and “woken up” actual working capacity will never ever be as great as when they were previously stowed away.

My 13Ah F cell packs still deliver about 6Ah after they’ve been cycled a few times. I do have a use for them to power my field RC charging equipment but I have witnessed their true working capacity slowly dwindle as the years go by.

 

[redilast]

In particular the effect of peak charge voltage, 4.0-4.25 volts , etc is historically mentioned as a life killer, but is that actual peak charge voltage or if a cell is maintained at that voltage for some time (how long ?).
But for sure, if your charger only leaves the cells at 4.0v then yes, you are only going to get 65% capacity.....
......or if you think about it , there is another 50+% capacity available if you boost that charge up to 4.2v !

The negative effects of fully charging a Li-ion are mainly (as I understand it) a problem if you frequently allow the cell to "hang out" at 4.20v for extended periods of time. For example you pull in on your ebike at 5PM and charge it up. By 9PM its charged and it sits at 4.20v until 8AM the next morning. So its basically spending half of the day, every day at 4.20v. In cases like this it would probably be best to use a timer charger, or slow down the charge rate so the cells don't "hang out" at 4.20v for an extended period of time.

In an ideal world for most electric vehicles you do not use the entire capacity of the battery everyday, not even close. In those cases I would prefer to just charge up to 3.9-4v per cell. If chargers had a high cycle life button and an extended range button that you could press that would be really nice. Say you want to go on an extended trip you just hit a button the day/night before and you have full 4.20v charging, but for normal daily use you charge to 3.9-4v per cell.

NASA has some cells/packs with shallow DOD that have exceeded 10,000 cycles some are over 75,000 cycles. By the way I found this NASA document interesting about the charge rates. High charge rate like 1C charge rate is really bad for cycle life! https://batteryworkshop.msfc.nasa.gov/presentations/Perf_Safe_Test_Panasonic_Li-Ion_NCR_18650_Cells_JRead.pdf

 

[ctirad]

My evelo 48 volt 500 watt ebike has over 3000 miles.
...
Ebike still runs well but range isn't what it used to be.

First of all, tell us what battery do you have, how old is it and what type of cells are inside.
While the SLA and old LiCo li-ion cells degrade pretty quickly with time, the LiFePO4 or modern li-ion chemistry cells should last multiple times of your range when they are handled properly. The later ones could be only disbalanced and that can be easily fixed.

 

[Hillhater]

....
NASA has some cells/packs with shallow DOD that have exceeded 10,000 cycles some are over 75,000 cycles. By the way I found this NASA document interesting about the charge rates. High charge rate like 1C charge rate is really bad for cycle life! https://batteryworkshop.msfc.nasa.gov/presentations/Perf_Safe_Test_Panasonic_Li-Ion_NCR_18650_Cells_JRead.pdf

I wonder what cell chemistry those high cycle life cells are that NASA tested ?..anything abnormal ?
Also, either Panasonic have dramatically changed the chemistry/performance of the cells used by Tesla, .....or using Teslas "Superchargers" are going to do serious damage to their EV packs life with those high charge rates, ..if the NASA data is applicable.

 

[redilast]

....
NASA has some cells/packs with shallow DOD that have exceeded 10,000 cycles some are over 75,000 cycles. By the way I found this NASA document interesting about the charge rates. High charge rate like 1C charge rate is really bad for cycle life! https://batteryworkshop.msfc.nasa.gov/presentations/Perf_Safe_Test_Panasonic_Li-Ion_NCR_18650_Cells_JRead.pdf

I wonder what cell chemistry those high cycle life cells are that NASA tested ?..anything abnormal ?
Also, either Panasonic have dramatically changed the chemistry/performance of the cells used by Tesla, .....or using Teslas "Superchargers" are going to do serious damage to their EV packs life with those high charge rates, ..if the NASA data is applicable.

There are just tons and tons of NASA documents for battery tests they have done. If you google search NASA and 18650 you'll find tons of PDF's and other tests they have done. I've seen them get 10,000's of thousands of cycles from ordinary 18650 just doing very shallow DOD cycles like 30%, and I'm sure also keeping the temperatures mild.

Tesla claims their cells is "customized" from Panasonic. Some people think its the same thing or very similar to the NCR18650BE, which is a 10A capable cell. The internal resistance is around 25 mili ohms @ 1Khz AC if i recall correctly. NCR18650B's are generally 38-40 mili ohms @ 1Khz AC. So the lower resistance coupled with liquid cooling maybe allows them to fast charge quite well.

From the superchargers Tesla claims something like an 80% charge / 200 miles of range in a 30 minute charge. So that would have to be roughly a 1.5C charge rate at a mostly flat CC (constant current) with little to no CV (constant voltage) stage.

It would be interesting though to see a comparison of a Tesla's battery pack condition of a customer that regularly uses super charges vs someone that doesn't. I have a friend that just got a model S. His uncle has a model S as well and charges almost exclusively at the free charging stations near his house. I wonder if he's going to need an under warranty pack replacement?

 

[Hillhater]

Im thinking that if the NASA data that you posted above is relavent to the majority of 18650 Li*** type cells with a 1C charge pretty much distroying the cycle life,...then the Tesla Supercharger is going to be an issue.
If , however, for some reason ,there is some difference between the cells NASA tested , and Tesla's cells, that dramatically change the results and the 1.5C + that the Supercharger applies doesnt affect cycle life,....then we shouldnt put much faith in any of the NASA tests being relavent to any cells we may be using.....unless they are exactly the same cell as NASA tested. ( highly unlikely) !
Im also guessing Tesla will have tested the affect Supercharge charge rates has on their various cells.
They cannot both be right !

 

[redilast]

Im thinking that if the NASA data that you posted above is relavent to the majority of 18650 Li*** type cells with a 1C charge pretty much distroying the cycle life,...then the Tesla Supercharger is going to be an issue.
If , however, for some reason ,there is some difference between the cells NASA tested , and Tesla's cells, that dramatically change the results and the 1.5C + that the Supercharger applies doesnt affect cycle life,....then we shouldnt put much faith in any of the NASA tests being relavent to any cells we may be using.....unless they are exactly the same cell as NASA tested. ( highly unlikely) !
Im also guessing Tesla will have tested the affect Supercharge charge rates has on their various cells.
They cannot both be right !

I think there is no doubt that higher charge rates destroy cycle life. However the tesla cell does have lower internal resistance than the NCR18650 listed in the NASA tests, and I think the Tesla cells also lack a PTC and CID device, which will lower the resistance even more. Many power tools don't have a PTC but I think most if not all still have a CID. I don't have any data to back this up, but I believe that 1C charge rate for power tool grade cells such as the Samsung 25R / Sony VTC5 would have very little effect on the cycle life vs charging them at like 0.2C. But it will have a greater effect on the cycle life on higher resistance cells.

I'm sure Tesla crunched the numbers and did tests and they probably figure that on average people will only use a super charger a few times a year, and that added wear for most customers is probably no big deal. But I'd be surprised if there is not premature wear on packs from customers that regularly use super chargers.

 

[999zip999]

Charge and discharge rates all depends on the quality and type of the cell. Some cells don't mind a higher charge rate. Most don't. Worst is discharging at to high a rate. Like long hills or sand.

 

[dogman dan]

Well, most of us want to have the battery charged, so you can hop on and ride. And in summer, it's 100F or so. Its pretty warm, and the battery is full charged,

2-4 years, and likely some noticeable capacity lost by year two. Which is why you buy a 15 ah, if your typical ride needs 10 ah. So you can still make it there in the third year.

This loss of capacity can apply, even if the pack has very few cycles on it.

When you get your new pack, consider charging to 80 or 90% full most of the time. Then you can just top it off fairly quick when you need to ride. There are chargers that you can flip a switch, and charge 50%, 90%, or 100%, at EM3ev. Doing this can make a pack lasting 3 years into a 4 year.

 

[jimw1960]

I have a Ping battery going on 7 years old. I don't ride it that much anymore but every few months when I pull it out, it is still fully charged and still has plenty of range. So probably number of cycles is the determining factor in battery life. Shelf life doesn't seem to be an issue.

 

[redilast]

I have a Ping battery going on 7 years old. I don't ride it that much anymore but every few months when I pull it out, it is still fully charged and still has plenty of range. So probably number of cycles is the determining factor in battery life. Shelf life doesn't seem to be an issue.

If stored at a reasonable voltage level generally 20-60% SOC and at room temperature then for most packs they will be just fine after years of storage.

However I've come across some cells over my years of testing where batteries literally doubled in internal resistance and lost capacity while just sitting idle for 1 year. The cells I can remember doing this were some early Samsung 28A's (4.30v 2800mAh) cells, and some MNKE IMR 1500mAh cells.

 

[dogman dan]

That's interesting, seeing as San Antonio is a bit warm in summer. What temp would you say it's stored at? And apparently stored full too.

This is the first I've heard of a Ping going much more than 4 years. If the battery is big enough, and the controller modest, it may be you don't notice the rise in internal resistance that much. What I mean is, if your typical discharge rate is below 1c, it could be low enough to seem normal still, and still dish out 70% capacity. But it might not do so great if you pull 2c from it.

But if that's the case, then it's still quite usable for your particular setup. 8)

That's sort of how my really old lipos act. 50% capacity if I try to use them as a 10 ah pack. They get a bit hot discharging. But bundle 30 ah of it together, so I'm discharging at .5c, and they seem pretty ok. Capacity back to about 70% . The pack stays cool. What gets noticeable though, is the way they charge. They get almost full, and then just seem to sit there for hours, just can't get that last volt to go in.

 

[jimw1960]

That's interesting, seeing as San Antonio is a bit warm in summer. What temp would you say it's stored at? And apparently stored full too.

This is the first I've heard of a Ping going much more than 4 years. If the battery is big enough, and the controller modest, it may be you don't notice the rise in internal resistance that much. What I mean is, if your typical discharge rate is below 1c, it could be low enough to seem normal still, and still dish out 70% capacity. But it might not do so great if you pull 2c from it.

But if that's the case, then it's still quite usable for your particular setup. 8)

That's sort of how my really old lipos act. 50% capacity if I try to use them as a 10 ah pack. They get a bit hot discharging. But bundle 30 ah of it together, so I'm discharging at .5c, and they seem pretty ok. Capacity back to about 70% . The pack stays cool. What gets noticeable though, is the way they charge. They get almost full, and then just seem to sit there for hours, just can't get that last volt to go in.

I keep the bike in my storage shed, so it can get pretty hot in the summer. It's a 48v20ah battery used with a 25-amp controller, so it doesn't have to work that hard. I'd say in total there are only about 300 cycles on it, most not going below 50% SOC. Frankly, I'll be disappointed if I don't get 10 years out of it.