Battery maintenance....

[markaus]

I am wondering what is the best approach to maintaining a 36v 16ah GM lithium ion battery in the following scenario.

A trip into town and back is 24 km. I reckon I will get about 3 trips on a fully charged battery (doing a bit of pedalling).
Is it best to;
1. Charge after each trip.
2. Charge after 3 trips when battery is near depletion.
3. Use some other strategy?

My bike use is a bit haphazard. I might go to town 3 times in one week and then only once the next.

All thoughts/recommendations appreciated.

[Andrew]

keep the  battery topped up to lengthen the lithium batteries life.  So after every trip. the less drainage the better

[Hardcore]

charge whenever you can ;P

[Sangesf]

I try to keep the charge cycles low while still not waiting to go to low on SOC.
I have a 36v 15ah that has over 1,000 cycles and still has 90-95% of it's rated AH (over 2.5 years of use) and I would say that 75% of the time, I waited until about 75% depletion before recharge.  15% of the time after 10-70% depletion and 10% of the time after full depletion.  

[_GonZo_]

In your case that you only use around 25-30% of the battery capacity on every use, the best will be to charge the battery just before every use up to 90-95%
I don't think that your charger let you do that. So then the best strategy is to top charge the battery just before you are going to use it.

What I mean is that if you are not going to use the battery next day, leave like it is at 70-75% and just charge it fpr example the night before the day you are going to use it.

If you can not exactly plan when you are going to use it, just charge it after every use.

[markaus]

Thanks folks for the ideas.

I wonder about whether a charge to full from say 75% full, ie after each trip to town counts as a charge cycle?
If a battery lasts approx 800 charge cycles, does it mean that this charging regime will shorten its useful life, as opposed to charging less often at near depletion?
I am confused about this which prompted the initial post.

Can anyone clarify this for me?

[Hardcore]

it's 1000 cycles from about 5-10% and if you charge it at 50-55% you'll get 2000 cycles, maybe just a bit less

[_GonZo_]

Actually it is not a question of cycles.

A battery is able to Charge discharge a certain capacity (Ah) throw its life.
For example:
If you discharge/charge 100% every time it may do 1000 cycles.
If you discharge/charge 50% every time it may do 2000 cycles.
But actually in both cases the battery have made the same charge/discharge work...

Although the way the cycles are done may influence the battery life.
Lithium batteries works better and suffer less on medium cycles, never fully discharged never fully charged.
So if you discharge/charge 50% every time it may do 2500 cycles instead of the 2000 logically estimated.

Hope it is clear.

[markaus]

Actually it is not a question of cycles.

A battery is able to Charge discharge a certain capacity (Ah) throw its life.
For example:
If you discharge/charge 100% every time it may do 1000 cycles.
If you discharge/charge 50% every time it may do 2000 cycles.
But actually in both cases the battery have made the same charge/discharge work...

Although the way the cycles are done may influence the battery life.
Lithium batteries works better and suffer less on medium cycles, never fully discharged never fully charged.
So if you discharge/charge 50% every time it may do 2500 cycles instead of the 2000 logically estimated.

Hope it is clear.

thanks Gonzo,
that clears the waters for me a lot!
regards

[GM Canada]

Actually it is not a question of cycles.

A battery is able to Charge discharge a certain capacity (Ah) throw its life.
For example:
If you discharge/charge 100% every time it may do 1000 cycles.
If you discharge/charge 50% every time it may do 2000 cycles.
But actually in both cases the battery have made the same charge/discharge work...

Although the way the cycles are done may influence the battery life.
Lithium batteries works better and suffer less on medium cycles, never fully discharged never fully charged.
So if you discharge/charge 50% every time it may do 2500 cycles instead of the 2000 logically estimated.

Hope it is clear.

Thanks for that! I learned something today

Gary

[Andrew]

So the higher capacity(Ah) battery you can carry with you the better! Due to less creating less drain. 

[_GonZo_]

So the higher capacity(Ah) battery you can carry with you the better! Due to less creating less drain. 

Extremely correct.
A golden rule for any battery powered device:
SAVE WEIGHT ON EVERYTHING SO YOU CAN ADD IT TO THE BATTERY

Trying to save weight or money on a small battery is the worst you can do because at the end you finish with a device that do not work properly, not enough range, not enough power, and at the end the battery dies prematurely because it was undersized... so you have to buy again...

Think for example on the cheap cell phones that the battery runs for less than a day... it is a night mare. Will not you prefer for example a 15gr more weight on the cell phone but that it last 3 days?
BTW my cell phone battery last around a week with out charging  it weights 12gr. more