Best voltages and methods to cycle lithium cells between?

[Mikes1992]

I've read it you cycle a lithium cell between 100%-0% you might only get 500 cycles while if you cycle between 10-90% you might get 2,000 cycle and 20-80% could get 5,000 cycles. and some claimed if you cycle right in the middle of the cell you can get upto 20,000 cycles!

Does anybody know the best voltages to cycle between? I barely use the capacity of my Ebike battery so I could probably goto the extremes of cycling between 60%-40%. the thing that I don't know though is the relationship between the charge level and voltage and if I cycle my cells between say, 4v(90%?) and 4.2v (100%) would that effect cycle life the same as going from 100-0%?

any input or any information about the best way to cycle cells would be great... currently I've been charging upto 4.1v/cell on my scooter and I usually use around 50% of the battery pack so maybe I should charge to a lower voltage? the performance drops a bit at lower voltages though

I was charging my ebike upto 4.2v and only use 25% of the pack, after reading more into cycling I think I might start reducing the voltage allot more.... performance isn't really effected because the voltage is already pretty high (it's a 48v battery, which tops out at 54.6v)

 

[Kinninvie]

Read the link below.
Its a bit long but may just save you destroying your batteries and a lot more besides.
If you discharge a Lipo to 0% then try charging it you will most likely end up with a serious fire!
https://endless-sphere.com/forums/viewtopic.php?f=14&t=52240

 

[flecc]

I've read it you cycle a lithium cell between 100%-0% you might only get 500 cycles while if you cycle between 10-90% you might get 2,000 cycle and 20-80% could get 5,000 cycles. and some claimed if you cycle right in the middle of the cell you can get upto 20,000 cycles!

With the exception of the 500 charges if fully charged and discharged within the limits set by e-bike controllers and battery BMS's, these are fantasy figures.

The only evidence is from satellite usage. In those only 13% of the battery content is used and then replaced in each 24 hour cycle. Their batteries are perfectly normal lithium types and last the specified 10 year span, meaning some 3700 daily charges.

That 13% will be from a full charge point, but no doubt the upper cutoff voltage is set lower than usual in the interest of long life Possibly around 80% of maximum capacity. That would leave the discharge/charge between 67% and 80%, but I can't say what the voltages are at those points.

That's academic of course, in practical e-bike use I don't think you'll get very much life extension by charge end constriction, since the charge ends are already constricted by design.

Probably the best you can do if your battery has a five LED meter is to operate over a middle two or three LED span.
.

 

[anotherkiwi]

If you use your bike for going places the calculation is completely different of course.

In the last year I have done +3000 km without worrying about charging to 90% and using it down to empty when it has to be done. Amortising the battery it has cost me 12.30€ / 100 km. If I had taken the bus to do the same 100 km it would have cost me 14.28€.

After a year the battery is showing no more wear and tear than after the first 3 months when performance went down slightly. I am already in the money every ride I do in the next year is only bringing my travel costs down. Get on your bike ride it, charge your battery, go to bed and sleep on both ears!

 

[Mikes1992]

Probably the best you can do if your battery has a five LED meter is to operate over a middle two or three LED span.
.

I use a multimeter to take messurements (and also to make sure the battery isn't overcharging) and divide the total pack voltage into the number of cells within the pack (54.6v / 13 cells = 4.2v per cell)

 

[flecc]

I use a multimeter to take messurements (and also to make sure the battery isn't overcharging) and divide the total pack voltage into the number of cells within the pack (54.6v / 13 cells = 4.2v per cell)

Either way, voltage or using the LEDs if provided, you can choose a middle span to operate within, for example 44 volts to 51 volts, if that span gave you enough range. Im basing that on the fact that a designed BMS for your battery would have a low voltage cut-off at 40 volts, so you'd be keeping around 4 volts away from either charge state extreme.

In the light of experience gained and range needed, you could adjust those figures to give more or less end cushioning. Of course you'd need a volt meter connected and preferably on the handlebars if using the voltage method, only taking readings when off motor load.
.

 

[Hermann R.]

Hello!
Cycle lifetime depends on Li-ion chemistry, depth of discharge (DOD), discharge current (!) and temperature.
Best you can do is check what kind of cells are in your battery and/or look up some manufacturer datasheets (for example 18650) to find out more about cycle life expectancy.
-Hermann-

 

[KeithMac]

I've always run my phones from 100% down to 5% or less and never had to replace a battery in any of them (my old one's still going at 5 years old).

The battery/ charging curcuit shoud have built in failsafes to avoid damage from overcharge or low voltage.

I have various drills and tools that use lithium batteries, I always run them down and let the charger condition and recharge the batteries.

As said above, best off leaving the electronics to sort it out and just enjoy the bike.