Battery Re-charging

FatBob

Pedelecer
Apr 15, 2020
138
36
Greater Manchester
What's the 'best' level at which to re-charge a Li-ion battery? Are you supposed to avoid running down a battery to prolong its life?
 

Michael Price

Esteemed Pedelecer
Sep 7, 2018
276
177
It depends on what your intentions are
If you are planning a long ride tomorrow then a full charge seems to be fine
If you are planning to leave the battery in storage for several weeks or months then you are supposed to charge to about 50-70% . How you do this depends - the best idea I have seen is to do a full charge then go out for a ride.

If the battery is a good make then the BMS will protect the battery and stop you doing too much damage. Mine is a Bosch system and I asked them specifically.
Main things are
a) don't charge it is cold temperatures -
b) don't leave for months on full charge

c)Try to use it every few months even if not for long

d) Under no circumstances leave it on minimum charge for a long time. It always looses a small amount of charge when unused - and if it drops below a certain amount it cannot recover!
 
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FatBob

Pedelecer
Apr 15, 2020
138
36
Greater Manchester
Thanks Michael.

For everyday use, is it best to re-charge when level gets to say 50% or 20% or 10%?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,143
8,233
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West Sx RH
The best level to recharge is the nominal voltage or voltage it is left at, nominal being 3.6 - 3.7v. If you are using the bike regularly it doesn't really matter but once you get to 50/60% it depends on your usage/range, it may be more critical depending on the battery capacity and intended range. For local use of say < 4 miles pottering about on errands one doesn't need to keep charging, if going further a field then if below 80% then worth charging up.

My errand/commute bike now only uses a 6ah battery with only a real world usage of 5.3ah at the given minimum current discharge I use, and is capable of 30 miles. I use miles per charge rather then being pedantic about voltage and will charge any where after 20 miles of use.

If there is no real need to go very deep discharge wise then stop at about 40/50%, deep discharge won't hurt and is a safety minimum limit should you need to use the max out of the battery on a ride.
 
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Michael Price

Esteemed Pedelecer
Sep 7, 2018
276
177
I generally get 2 bikes rides out of each charge
So - assuming I am riding most days - I recharge every other ride
If I am planning an especially long ride I will probably charge it anyway just to prevent any problems.

If I was probably not riding it for a few week - e.g. if we were going on holiday soon - then I would try to leave it at about 50% while I was away
 

FatBob

Pedelecer
Apr 15, 2020
138
36
Greater Manchester
Thanks. I just didn't want to think re-charging a battery currently at 50% to 100% (to give full range at the next outing) would cause the battery harm or risk explosion, even if the charging unit light was already green (indicating "full charge"), or letting the capicity fall below, say, 10% would shorten the life of the battery.
 

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