Battery charging routine?

[AnonymousLurkerer]

For reference, I just got my first ebike and it came with a Bosch PowerTube 500Wh. After a few workouts, I find that I usually drain 70-85% of the battery after a ~20mile ride. Sometimes I do the same route on consecutive days, so I just put the bike on the charger right when I get home from a ride and let it sit at 100% overnight.

What kind of factors affect the charge-cycle lifetime of ebike batteries? Is it straining on the battery to leave it at 100% charge for days before I go for another ride? Is it better to just charge it right before I go for a ride so that the battery spends as little time at 100% charge as possible? I guess I am assuming that more charge left in a battery is what decreases its lifetime, because I saw a statistic that you can increase lifespan (ie. total charge cycles) of ebike batteries by +20% by only charging them to 80% max charge vs all the way to 100% every time. Additionally, I have found so far that the battery naturally drains 2-4% per 24hr while just sitting unused.

So my question is: Should I leave my battery at 10-20% capacity after my workout before I charge it for my next ride, or will charging it to 100% right after my ride not noticeably affect the battery’s lifetime?

Thank you all for your invaluable ebike knowledge that apparently is quite scarce, given the disappointment I have received from several bike shops I have tried to visit for guidance so far.

 

[ElevenAD]

1)wait a little while before charging after a ride, at least give it 20mins to cool off
2) constantly draining your battery below 20% will shorten the batteries life
3) i would not constantly leave my battery on the charger overnight,the charger has a shut of and the battery has a BMS but
its still not something i would advise doing every charge.
4) i dont like to leave my batteries at 100% for more than a day or two.

 

[Gionnirocket]

1)wait a little while before charging after a ride, at least give it 20mins to cool off
2) constantly draining your battery below 20% will shorten the batteries life
3) i would not constantly leave my battery on the charger overnight,the charger has a shut of and the battery has a BMS but
its still not something i would advise doing every charge.
4) i dont like to leave my batteries at 100% for more than a day or two.

All good advise.
I'd add... charge it to 80%....then to 100% just prior to a ride if you require the full capacity.
Losing 3% capacity just sitting is excessive.. 24 hour loss should be close to 0. Is this consistent? or just the first 24 hours after a charge?
If the battery has a switch turn it off. If not you may want to remove it from the bike while sitting and see if you have the same results.
If your display has the option to display volts instead of percentage, that is more useful information.

In the meantime.. You can give this a read Batter Guide

 

[Two is Better than Four]

This is all good advice. My question is, how do you check a battery that's being charged if you only want to get it to ~80%? Is purchasing a voltmeter worthwhile? Is there another rule of thumb - say charging for only 2-3 hours after a ride and using a timer to shut of the charger? I've heard that it's best to keep your battery in the 20% - 80% range. FYI - I have a Bafang Ultra 1000W Mid-Drive.
Thanks

 

[AHicks]

An opposing view, based on many years screwing around with batteries in radio control and a lot of research as crashes are expensive!

I AM a fan of frequently charging to 100% and leaving the charger on over night - especially the first few charges on a new battery. Why?

It's about balance charging, making sure ALL cells are getting a good charge. That's NOT happening with an 80% charge.

Not saying you need to fully charge a well balanced battery every time. It's just that I believe it needs to happen frequently, maybe 1 charge in 3 or 4 should be a full, 100% balance charge. Just don't leave one of those 100% fully charged batteries sitting for weeks. Try to do that knowing you'll be riding the bike within 24 hours or so of the full charge.

And more than anything else, as long as you aren't sucking every last drop of power from your battery prior to charging it, you really don't need to over think this charging thing. Not like a lot of guys do anyway.....

 

[Sierratim]

This is all good advice. My question is, how do you check a battery that's being charged if you only want to get it to ~80%? Is purchasing a voltmeter worthwhile? Is there another rule of thumb - say charging for only 2-3 hours after a ride and using a timer to shut of the charger? I've heard that it's best to keep your battery in the 20% - 80% range. FYI - I have a Bafang Ultra 1000W Mid-Drive.
Thanks

Some ebikes display the battery charge level as a %. For those that don't you'd need a voltmeter ($) or a programmable charger ($$$). The attached table gives battery voltage vs % charge for most common battery packs.

 

[Gionnirocket]

An opposing view, based on many years screwing around with batteries in radio control and a lot of research as crashes are expensive!

Different battery chemistries, pack configurations, discharge needs and the absence of a BMS.
Good as some background experience but & my friend.

 

[J.R.]

I don't charge directly after a ride, usually wait an hour or so. Then I'll bring the charge up to 60 to 80% capacity. 60 if it will sit for a day or so, 80 if I'm going to ride the next day. I will top up the battery before the ride. I have also used a timer to top up the pack if I am riding early. One of my packs is 5 years old and still going strong. I'm amazed how well my packs are doing. One six year old pack that is ready to be replaced, but it is a LiFePo4 older chemistry for an old bike. One 5 year old pack that has lost very little in range, maybe 15%. And two packs going on 2 years old (~1-1/2). I also have friends with both old and new packs, treated well they can last a long time.

 

[Gionnirocket]

I don't charge directly after a ride, usually wait an hour or so. Then I'll bring the charge up to 60 to 80% capacity. 60 if it will sit for a day or so, 80 if I'm going to ride the next day. I will top up the battery before the ride. I have also used a timer to top up the pack if I am riding early. One of my packs is 5 years old and still going strong. I'm amazed how well my packs are doing. One six year old pack that is ready to be replaced, but it is a LiFePo4 older chemistry for an old bike. One 5 year old pack that has lost very little in range, maybe 15%. And two packs going on 2 years old (~1-1/2). I also have friends with both old and new packs, treated well they can last a long time.

Sounds like a plan that is working... a few questions if I may.
What do you mean by top up? And how much capacity do you use up on a typical ride

 

[AHicks]

Different battery chemistries, pack configurations, discharge needs and the absence of a BMS.
Good as some background experience but & my friend.

RC matteries are Lithium based, and run at the same voltages as the cells we use, making them close enough to be very relevant. As far as not having a BMS, the RC charging technology is far more sophisticated and include real time displays so you can see exactly what's going on. Chargers can display voltages for any cell during the charge - which leads to some pretty decent insight regarding what's going on during any phase of the charge cycle. And last, I've been using these long enough to know what kills them, how they act when you can no longer trust them, and how long they last.

You want to believe apples and oranges, then go for it. I know better.... -Al

 

[Gionnirocket]

RC matteries are Lithium based, and run at the same voltages as the cells we use, making them close enough to be very relevant. As far as not having a BMS, the RC charging technology is far more sophisticated and include real time displays so you can see exactly what's going on. Chargers can display voltages for any cell during the charge - which leads to some pretty decent insight regarding what's going on during any phase of the charge cycle. And last, I've been using these long enough to know what kills them, how they act when you can no longer trust them, and how long they last.

You want to believe apples and oranges, then go for it. I know better.... -Al

Will you accept & ?
Yes I am quite aware of how hobby charging works and you forgot to mention that you can even monitor internal cell resistance
But I think what you believe you know better is clouding your understanding of the differences. And just because people think, doesn't mean that they are over thinking about it or stressing.
After all I thought this forum was here for discussion.

 

[AHicks]

Read your last reply, the one that said I was comparing apples and oranges, then repeat what you just said - the part where " I thought this forum was here for discussion".

I think I'm here for the same reason. The fact my opinion may differ from yours doesn't necessarily mean I'm comparing apples to oranges.

I don't like to see this 80% charge topic brought up with no mention, or additional info, regarding the need to balance charge frequently. It's that simple really.... -Al

 

[Gionnirocket]

The fact is that your opinion isn't that different than mine... I too agree that you need to balance... maybe just not as frequent as you.

Where we differ is that I don't equate our batteries to high discharge rate Lipo's.
How about peaches & nectarines?

 

[AHicks]

Close enough. I give up.

 

[Gionnirocket]

Close enough. I give up.

The main reason for my thinking that they are different is the high discharge rate and the typical use of Lipo's which are designed to unload thier energy quickly which in turn creates a lot of heat. Heat is the number one factor in battery degradation and what leads to unbalanced cells. Whenever I've removed a Lipo from an RC just after use, it was way above ambient temperature. I've yet to see my battery feel even slightly above ambient temp except for sun exposure.
Granted I do a lot of the work when riding and someone who is riding competitively or in a taxing terrain may have greater strain on their battery which would probably benefit from more frequent balancing.
Bananas & Plantains... my final offer

 

[Lectric Bill]

In thinking about how to consistently charge to 80% , I came up with a spreadsheet which I keep in my phone: Charge Time Calculator
I start with the percentage SOC at the end of a ride.

Using trial and error, I came up with a factor to determine the time I need to charge to get from the initial percentage to 80%.
(Note: The factor I came up with is based on a Specialized Turbo Como 5.0, the OEM charger and I started with the published time for a full charge, tweaking it until I hit 80% fairly consistently.)

The spreadsheet gives me the hours and minutes I need to charge which I use to set my phone's countdown timer.

 

[linklemming]

An opposing view, based on many years screwing around with batteries in radio control and a lot of research as crashes are expensive!

I AM a fan of frequently charging to 100% and leaving the charger on over night - especially the first few charges on a new battery. Why?

It's about balance charging, making sure ALL cells are getting a good charge. That's NOT happening with an 80% charge.

Not saying you need to fully charge a well balanced battery every time. It's just that I believe it needs to happen frequently, maybe 1 charge in 3 or 4 should be a full, 100% balance charge. Just don't leave one of those 100% fully charged batteries sitting for weeks. Try to do that knowing you'll be riding the bike within 24 hours or so of the full charge.

And more than anything else, as long as you aren't sucking every last drop of power from your battery prior to charging it, you really don't need to over think this charging thing. Not like a lot of guys do anyway.....

Im also from an RC background(FPV drones, helis and cars) FWIW.

It was standard practice to break in pack by cycling about 3-5 times. Charging 1-2C and discharging around 1C. I noted a definate difference in pack power and longevity if I didnt do it. I also parallel charged but not while cycling a battery.

While I somewhat agree with Al that its good to go to 100% charge sometimes, it really all depends on the BMS. Some BMS only balance at full charge and some do not require full charge from what I have researched. Best to be safe and just go to 100%.

I usually keep my packs about 1/2 full until the night before I want to use them then go to 100%.

I did try 80% and 90% charge a few times but then encountered range anxiety too much so I just go with 100%

 

[FlatSix911]

Here is a handy charging guide, thanks to Ravi... charging from 20-80% will provide the maximum lifespan.

 

[6zfshdb]

Here is a handy charging guide, thanks to Ravi... 20-80% will provide the maximum lifespan.

As others have said, there is no reason to over think this. If you follow Ravi's 9 step chart above, you'll be fine.

In my case, I always charge to 100% before a ride simply because I need the extra range it provides. I never maintain 100% for more than a day or so. My batteries are 4 years old now and bench tests show they have lost less than 6% of their original capacity. How much of this loss is due to age vs usage is unclear.

Another thing to consider: Does your OEM charger really charge to 100% before shutting off? According to measured voltage, my charger cuts out at 92%. From what I've seen, this can vary by manufacturer. To get a true 100% charge, I bought a Grin Satiator programmable charger which cost about half that of a new battery!

I see no reason to "baby" a battery to the point where it outlasts the useful life of the e-bike. There are new, cheaper, higher capacity and lighter weight batteries on the horizon and I may well want to replace the ones I have anyway.

 

[Dale C]

I charge my Bosch gen 2 battery when i get home from work. It stays on the charger overnight and shuts off on its own. Just my opinion, the minor gains in battery life are not worth the effort of trying to outsmart the battery management system. The engineers who designed this system have far more experience and education than I do. I paid for their expertise and manufacturing allowing me to just enjoy the ride without worrying about it.