Electric bike battery care

[Oski1997]

I agree with @AHicks . If you are not actively using the 2nd battery, then you may not see a huge benefit by alternating the batteries.
May I ask you this?
How many miles do you ride per year?
With proper care, Yamaha batteries can serve you well for 30,000 miles or more. So, that's like 3-4 years of heavy riding.
if you get 30 miles per charge cycle (cycling between 85% to 15% should give you 1500 usable cycles) and that's 30 X 1500 = 45,000 miles.
By alternating another battery, you can not prolong that number to 80,000 miles because of the inherent calendar aging.

Ravi, depth of discharge seems to be the main factor that contributes to a significant loss of cycles (after temperature factors, of course). In this graph (see pic) it shows that I would get 1,000 cycles when using a Depth of Discharge of 80%-85% (which I believe means using a battery from 90%-10% or 90%-15%). This is a 75% loss in battery capacity compared to using a DoD of 60-65% (charging up to 80% and using it down to 40%) which would give me 4,000 cycles. Are you saying that regardless of these figures our ebike batteries will only give us 1,500 cycles no matter what because of Calendar Aging? We should disregard these numbers? Doesn’t this study support the notion that I could get 4,000 cycles in each battery if I only charge them up to 80% and use them down to 40%? Or is this just theoretical?

 

[Oski1997]

Ravi, depth of discharge seems to be the main factor that contributes to a significant loss of cycles (after temperature factors, of course). In this graph (see pic) it shows that I would get 1,000 cycles when using a Depth of Discharge of 80%-85% (which I believe means using a battery from 90%-10% or 90%-15%). This is a 75% loss in battery capacity compared to using a DoD of 60-65% (charging up to 80% and using it down to 40%) which would give me 4,000 cycles. Are you saying that regardless of these figures our ebike batteries will only give us 1,500 cycles no matter what because of Calendar Aging? We should disregard these numbers? Doesn’t this study support the notion that I could get 4,000 cycles in each battery if I only charge them up to 80% and use them down to 40%? Or is this just theoretical?

Here is the link to the articles referencing the studies Ravi: https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

 

[Ravi Kempaiah]

Ravi, depth of discharge seems to be the main factor that contributes to a significant loss of cycles (after temperature factors, of course). In this graph (see pic) it shows that I would get 1,000 cycles when using a Depth of Discharge of 80%-85% (which I believe means using a battery from 90%-10% or 90%-15%). This is a 75% loss in battery capacity compared to using a DoD of 60-65% (charging up to 80% and using it down to 40%) which would give me 4,000 cycles. Are you saying that regardless of these figures our ebike batteries will only give us 1,500 cycles no matter what because of Calendar Aging? We should disregard these numbers? Doesn’t this study support the notion that I could get 4,000 cycles in each battery if I only charge them up to 80% and use them down to 40%? Or is this just theoretical?

Thanks for the link, @Oski1997 .

I actually wrote a detailed Electric Bike battery guide to help folks gain better understanding: https://electricbikereview.com/forums/threads/e-bike-battery-guide.24443/

Feel free to check out some of the attached videos and the whole thread could help you cover a lot more ground in terms of understanding the best practices.

 

[Oski1997]

Thanks for the link, @Oski1997 .

I actually wrote a detailed Electric Bike battery guide to help folks gain better understanding: https://electricbikereview.com/forums/threads/e-bike-battery-guide.24443/

Feel free to check out some of the attached videos and the whole thread could help you cover a lot more ground in terms of understanding the best practices.

Thanks Ravi, these studies seem to reference 4,000 life cycles with a 40% DoD used. Is there a reason you only go up to 1,500 cycles? Actually I found one of your slides. It shows a 4,500 life cycle when using a 60% DoD. This number is better. Is there a reason you believe a better DoD won’t yield a 4,000 life cycle?

 

[Ravi Kempaiah]

these studies seem to reference 4,000 life cycles with a 80%-40% DoD used. Is there a reason you only go up to 1,500 cycles?

The particular case you are referring to is DST (Dynamic stress test) conducted at 20'C and some other lab conditions. The chemistry of the cell would be different.
In real-life conditions, the results would be different. In the figure you shared in this post: https://electricbikereview.com/forums/threads/electric-bike-battery-care.36481/page-6#post-391973

If you are charging 85%, you would be able to eek out 1000+ cycles. That's pretty good.

For example, Li2TiO3 (lithium titanate) chemistry lasts 10,000 cycles or more, Lithium Iron phosphate also has a high cycle life but other chemistries used NCA (Tesla Model S) or NMC (Chevy Bolt/ Audi e-tron, etc) have slightly lower cycle life. there is a lot more to cycle life than just the chemistry. BMS, cooling system, charging protocols, usage, etc. all matter.

In summary, if you do a couple of things right, you get the benefit but trying to control the smallest details may or may not yield the results you are looking for.

 

[Oski1997]

The particular case you are referring to is DST (Dynamic stress test) conducted at 20'C and some other lab conditions. The chemistry of the cell would be different.
In real-life conditions, the results would be different. In the figure you shared in this post: https://electricbikereview.com/forums/threads/electric-bike-battery-care.36481/page-6#post-391973

If you are charging 85%, you would be able to eek out 1000+ cycles. That's pretty good.

For example, Li2TiO3 (lithium titanate) chemistry lasts 10,000 cycles or more, Lithium Iron phosphate also has a high cycle life but other chemistries used NCA (Tesla Model S) or NMC (Chevy Bolt/ Audi e-tron, etc) have slightly lower cycle life. there is a lot more to cycle life than just the chemistry. BMS, cooling system, charging protocols, usage, etc. all matter.

In summary, if you do a couple of things right, you get the benefit but trying to control the smallest details may or may not yield the results you are looking for.

Thanks Ravi. I trust you. I know there is nothing better than just using the bike/battery and seeing how long it lasts for me. Thank you for indulging me. I usually start all of my major purchases (from TVs to cars to A/C units for my home, to computers and now to ebikes) with fact-finding missions (lol). Then, once I believe I understand the “math/chemistry”, I do my real world experiments (which often means many returns and exchanges when the numbers don’t look right in the real world). Thank you for your time and thoughts.

 

[Handlebars]

Ravi, I recently bought a Yamaha Civante ebike. I bought an extra battery ($900) so I can save money in the long-run. My thinking is “if I spend $900 today, I shouldn’t need to buy another battery in a long time because I’m using a 75-25% rule” (i know it’s 80-20 but at $900/battery, I’m being more conservative). I’ve read that I can better maximize the cycles of a Lithium Ion battery if I use it from 75% down to 25% than if I used it from 70-20% because more damage can be done by charging below 20% (I hope that’s right). Do you agree? If not, I think I’d rather charge my batteries 70% down to 20% because less heat is produced by the battery if I stop charging at 70%. Since my bike can utilize active balancing at a lower threshold than 95%, do you happen to know what the threshold is for a 500wh Yamaha battery? If it’s 90%, then I’m not doing my batteries any good by only charging up to 75%. If it’s impossible to find out, then I’ll just charge to 100% 2x/year. Thanks in advance for your thoughts.

I'm of the opinion that it seems not to be a straightforward go, from looking at graphs of single cells' performances and lifespan under varying conditions to understanding whole-battery performance and lifespan due to draw and balancing issues.
If you have smart-balancing all the way during charging it may be that simple, but probably most do not have that kind of smart-balancing BMS.
If that is the case (it is for me), then the plan is more like "don't run the battery down past "x" volts, whether your belief is that 20% or 30% is "x" volts, the low limit.
On the belief of how often is best to charge past the "start balancing the cells" point, obviously if you have a simple BMS, it's an exercise in guesswork, shots in the dark, crossing fingers, etc.
I've kind of settled on charging to 100% every so often, but "how often is 'every so' ", is still in question.

I'd rather not charge to 100% if it's not doing any good and I'd do it more often if it is doing good. I have no way of knowing.

 

[Oski1997]

I'm of the opinion that it seems not to be a straightforward go, from looking at graphs of single cells' performances and lifespan under varying conditions to understanding whole-battery performance and lifespan due to draw and balancing issues.
If you have smart-balancing all the way during charging it may be that simple, but probably most do not have that kind of smart-balancing BMS.
If that is the case (it is for me), then the plan is more like "don't run the battery down past "x" volts, whether your belief is that 20% or 30% is "x" volts, the low limit.
On the belief of how often is best to charge past the "start balancing the cells" point, obviously if you have a simple BMS, it's an exercise in guesswork, shots in the dark, crossing fingers, etc.
I've kind of settled on charging to 100% every so often, but "how often is 'every so' ", is still in question.

I'd rather not charge to 100% if it's not doing any good and I'd do it more often if it is doing good. I have no way of knowing.

I have come to learn that I have a smart balancing BMS so I can use the battery from 90%-10% with very little effect on capacity degradation. I don’t quite understand why the two batteries won’t benefit from using them with a Depth of Discharge of 50% (i.e. only charging them up to 75% and rarely using them below 25%). It just doesn’t prolong their lifespan. For some reason batteries only last 3-4 years, period. Thank you for your reply.

 

[AHicks]

I have come to learn that I have a smart balancing BMS so I can use the battery from 90%-10% with very little effect on capacity degradation. I don’t quite understand why the two batteries won’t benefit from using them with a Depth of Discharge of 50% (i.e. only charging them up to 75% and rarely using them below 25%). It just doesn’t prolong their lifespan. For some reason batteries only last 3-4 years, period. Thank you for your reply.

That's it in a nutshell! If you take good care of them, with regular use and a little luck, you MIGHT get another year or 2, but it's difficult to plan on that....

As an example, I have a 4 year old RAD battery that's not showing any degradation I can see at this point. Still, it would be hard to find much fault with it if it started it's down hill slide the next time it's charged.....

 

[WinterKill]

What effect will storing lithium batteries for a few months, (disconnected from charging or load) at temperatures of 32F/0C to -25F/-32C have on the rated life of a lithium battery? (Note this is for a off grid cabin running off solar, note my bike batteries)

 

[Oski1997]

What effect will storing lithium batteries for a few months, (disconnected from charging or load) at temperatures of 32F/0C to -25F/-32C have on the rated life of a lithium battery? (Note this is for a off grid cabin running off solar, note my bike batteries)

According to one study, storing batteries at 0c has a small effect on lithium ion batteries if only charged up to 40%. I know the lower the temps get -32C the greater the degradation but I’m not sure by how much.

 

[WinterKill]

Thanks for the chart.

I have a small off grid cabin in Northern Minnesota that I need to upgrade my solar system to get enough capacity to charge two ebikes. I am thinking that I should be able to leave the batteries installed in the winter as long as I totally isolate them from any loads and the solar panels when I am not there and leave them some where between 40-60% charged.

I do use occasionally in the winter. When doing this I would not turn anything on if the battery temp is below 0F, only on small lighting loads until battery temp is over 32F. And then charge only after batteries are warmed up to 50F.

I am thinking that if I operate under these parameters my lithium battery life should not be overly degraded.

Am I missing anything with this thinking?

 

[Oski1997]

Thanks for the chart.

I have a small off grid cabin in Northern Minnesota that I need to upgrade my solar system to get enough capacity to charge two ebikes. I am thinking that I should be able to leave the batteries installed in the winter as long as I totally isolate them from any loads and the solar panels when I am not there and leave them some where between 40-60% charged.

I do use occasionally in the winter. When doing this I would not turn anything on if the battery temp is below 0F, only on small lighting loads until battery temp is over 32F. And then charge only after batteries are warmed up to 50F.

I am thinking that if I operate under these parameters my lithium battery life should not be overly degraded.

Am I missing anything with this thinking?

Form what I’ve read it’s better to not charge them over 50% when storing.

 

[Old Don]

The Satiator is an excellent product although a bit pricey. There have been many posts on the product if you do a search. I own one but find myself using the OEM charger on a simple timer most of the time. It's fairly easy to estimate the charge time to get the % charge I want.

I would use the Satiator more but it doesn't play well with the BMS in my battery. Whenever I connect it, I get a message that says to "connect a battery" even though it is already connected. I have to discharge the battery slightly or connect the OEM charger first to get the Satiator to recognize it. Once I do this, the charger works fine. It's a pain though, so I wind up using the OEM charger instead.

Keep in mind, the problem is with my battery, not the Satiator. I'm not knocking the product in any way.

 

[Old Don]

On one of my batteries, my Satiator will not start until I press the "force start" command on the Satiator menu.

 

[tomjasz]

On one of my batteries, my Satiator will not start until I press the "force start" command on the Satiator menu.

See this thread for force start information. https://endless-sphere.com/forums/v...p=1552601&hilit=satiator+force+start#p1552601

Or RFD!
5 Additional Features and Details
5.1 Force Start
In some scenarios, you may have a battery attached to the charger but the charger still says CONNECT BATTERY. For instance, this can happen if the battery has been drained so low that the battery management system's (BMS's) protection circuit inside your pack has shut off and disabled the battery output. If there is no voltage on the battery terminals, the charger will be unaware that a pack has been plugged in.
Figure 28: Force Start if battery not detected from tripped BMS
In this situation, pressing and holding the lower button on the CONNECT BATTERY screen will force the charger output to go active for a few seconds in order to begin a charge process. If it detects current flowing into the battery at a voltage

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www.ebikes.ca/satiator [email protected] +1(604) 569-0902

higher than the start voltage for the selected profile, the normal charge process will begin.

 

[Old Don]

See this thread for force start information. https://endless-sphere.com/forums/v...p=1552601&hilit=satiator+force+start#p1552601

Or RFD!
5 Additional Features and Details
5.1 Force Start
In some scenarios, you may have a battery attached to the charger but the charger still says CONNECT BATTERY. For instance, this can happen if the battery has been drained so low that the battery management system's (BMS's) protection circuit inside your pack has shut off and disabled the battery output. If there is no voltage on the battery terminals, the charger will be unaware that a pack has been plugged in.
Figure 28: Force Start if battery not detected from tripped BMS
In this situation, pressing and holding the lower button on the CONNECT BATTERY screen will force the charger output to go active for a few seconds in order to begin a charge process. If it detects current flowing into the battery at a voltage
View attachment 80547 View attachment 80546
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www.ebikes.ca/satiator [email protected] +1(604) 569-0902 View attachment 80548

higher than the start voltage for the selected profile, the normal charge process will begin.

Thanks for the reply. I have read this entire thread with great interest. Lots of information and ideas on charging and balancing batteries and cells here.
Presently, I believe that I may have slight problem with my 21ah, 48v. battery.
Have about 500 miles on the bike and never since day one, (Aug 2020) have i been able to have it reach more than 53.5 v. (with the stock charger or the Satiator).
Have ridden the voltage down to 43V approximately 4 or 5 times but never experienced a system shut down.
Should I be attempting to go for a shut down and then another full charge ? or does anyone have other ideas for a fix. Maybe 53.5 V is OK ?
Presently, bike is in storage until the snow goes, so really not that anxious to charge it up to full and store it right now.
thanks, Old Don

 

[legsofbeer]

never since day one, (Aug 2020) have i been able to have it reach more than 53.5 v.

What are you using to measure the battery? When the 9v reference battery in my multimeter starts to get old, the voltage measurements get wonky. Also, my controller display usually reads 0.2v lower than the fluke multimeter, which I will trust more than the display.

Have you ever done a balancing charge on the battery, however the manufacturer (bike or battery) says to do it? Mine recommends a once a month balance charge if one is riding regularly. My 48v battery at full charge tends to measure 53.7-9 near the end of the month, then 54.2 after balancing.

I would not recommend discharging the battery to BMS shutoff level for this; I don't see how that would help and it is extra wear on the battery.

 

[Old Don]

What are you using to measure the battery? When the 9v reference battery in my multimeter starts to get old, the voltage measurements get wonky. Also, my controller display usually reads 0.2v lower than the fluke multimeter, which I will trust more than the display.

Have you ever done a balancing charge on the battery, however the manufacturer (bike or battery) says to do it? Mine recommends a once a month balance charge if one is riding regularly. My 48v battery at full charge tends to measure 53.7-9 near the end of the month, then 54.2 after balancing.

I would not recommend discharging the battery to BMS shutoff level for this; I don't see how that would help and it is extra wear on the battery.

Thanks for the reply. Actually I believe that I did notice a difference of o.1 V between the multimeter and the display voltage.
I am only talking about a tad over 1 volt that I am missing, but that equates to a bit of range loss and top end performance.
Also, I don't see temperature as being a factor.
Just sitting tight for the present, waiting for a good weather window or spring to come to get the bike on the road again. thanks, Old Don

 

[Oski1997]

Hopefully Ravi will confirm this, but buying that second 900 dollar battery now is only useful if you need the additional capacity that it will give you. Buying now, for the purpose of extending the life of each battery, is a false economy.

That second battery, even if you only rarely/never use it, is deteriorating all by itself.

Using up the first battery, assuming only that it will get the job done for you most of the time, THEN buying a replacement battery that will do the same, will let you get more use than buying both to begin with.

I think you are right. I didn’t heard of calendar aging when I bought the 2nd battery. But, I do have some 50+ mile rides (now once every 6 weeks), so I will benefit from the 2nd battery. Thank you for your thoughts.