Battery care?

Hovlev2

Pedelecer
Jul 24, 2020
117
27
I'm probably opening up a can of worms here..... but having a new ebike (Oxygen S Cross MTB MkIII), I'm totally confused by advice regarding battery care.

Oxygen themselves advise to keep it fully charged (ie topped up every time you use it) for maximum life, but others insist that you never charge beyond 80%, then someone else tells you to take it down to 25% before charging.
Then another person will tell you that if you charge say only 25% every time, then when you've carried out 4 charges it only counts as one charging cycle, then yet another piece of advice will be that even a partial charge will count as a full cycle, so you'll be replacing your battery a lot sooner.

Does anyone have any definitive advice on this, as I'm totally confused! My battery, incidentally is an Oxygen 36 volt 16Ah, with (apparently) LG cells.

Thanks

Mick
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
1,862
1,278
You'll see lots of threads on that can of worms already. It is indeed confusing: I suspect that when all the answers are in on this thread you'll be more confused rather than less. My comments below based on what seems to be consensus opinion, not on my first hand knowledge.

* Try not to leave the battery on charge once it reaches 100%. Some chargers cut out at that point, but many continue providing small charge current which is bad for the battery.

* If you don't regularly charge to the full you should do so once a month or so to keep the battery balanced.

* Don't let the battery get very low, though the BMS should protect it if it does.

* If you need to store for more than a week or so make sure charge is somewhere between 50-80%.

* I understand that on modern batteries partial charges take a partial toll on it's life; and that suggestions that a partial charge is as bad as a full one are based on experience with earlier battery technology.

I tend to charge to 100% when the battery is about 1/2 full, or when I know a longer ride may be coming up. That's convenient and I think/hope it won't significantly reduce battery life.
 

Benjahmin

Esteemed Pedelecer
Nov 10, 2014
1,751
1,142
66
West Wales
Use it, charge it, enjoy it.
Try to charge as near to next use as possible.
Partial charges don't harm Li-ion technology. This comes from old Ni-cad technology.
If you're not going to use the bike for a period (weeks), charge it then go out and put 10-15 miles on it, then store it. Don't store fully charged.
Bike batteries need to be charged to full (charger lights green) in order for the cells to be balanced. Don't listen to those who advocate charging to 80%, they are taking information from sources talking about individual cells or e-car batteries. This does not apply to bike batteries with their simpler (less weight/expense) technology.
Get to know your usage pattern and terrain you're cycling. A fully charged battery is better than range anxiety and/or runnung out just on that last climb to home.
 
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Edward Elizabeth

Pedelecer
Aug 10, 2020
63
84
Central England
You'll see lots of threads on that can of worms already. It is indeed confusing: I suspect that when all the answers are in on this thread you'll be more confused rather than less. My comments below based on what seems to be consensus opinion, not on my first hand knowledge.

* Try not to leave the battery on charge once it reaches 100%. Some chargers cut out at that point, but many continue providing small charge current which is bad for the battery.

* If you don't regularly charge to the full you should do so once a month or so to keep the battery balanced.

* Don't let the battery get very low, though the BMS should protect it if it does.

* If you need to store for more than a week or so make sure charge is somewhere between 50-80%.

* I understand that on modern batteries partial charges take a partial toll on it's life; and that suggestions that a partial charge is as bad as a full one are based on experience with earlier battery technology.

I tend to charge to 100% when the battery is about 1/2 full, or when I know a longer ride may be coming up. That's convenient and I think/hope it won't significantly reduce battery life.
Good advice.

And every 30 or so charge cycles discharge it fully (as above, the BMS won't allow it to totally empty itself, and thus risk damage) and recharge it to 100% again.
 
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WallyM

Pedelecer
Aug 10, 2020
39
18
I assume the manufacturer of the bike has a manual with instructions how to charge the batteries....just read that and do as he suggests.

(Conspiracy theorists of course will say that some manufacturers he will mislead in order to sell more spare batteries, but that sort of scam would be outed within a few weeks and people could then successfully sue that manufacturer.)
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
1,862
1,278
I assume the manufacturer of the bike has a manual with instructions how to charge the batteries....just read that and do as he suggests.

(Conspiracy theorists of course will say that some manufacturers he will mislead in order to sell more spare batteries, but that sort of scam would be outed within a few weeks and people could then successfully sue that manufacturer.)
I agree, except if there were such a scam it would take much longer to become apparent. Look how long it took for the VW emissions scam to become apparent. Battery life issues are of their nature something that will not be obvious until the batteries start to wear out too quickly; even then the cause won't necessarily be at all clear.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
11,777
4,557
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West Sx RH
Use and ride it, if on a long run no harm will generally be caused by draining to LVC but be aware of voltage sag in higher assist level so better to use a lower assist to prevent the cut outs.
Charge up to 80% but not 100% unless going o use it straight away, a final top up too 100% a few hours before use is needed. If leaving battery unused for several weeks/months store at 50 - 80%. % can be hard to judge accurately so aim for 3.8v - 3.85v per cell group.

My town bike usually is only used for very short trips of about 5 or 6 miles, so batteries are only charged about once a week. Even then after some 40 miles between charges it still registers 36v +.

Simply put 100% charge at any stage is bad for lithium cells for a long period.
 
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Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
1,550
348
74
You'll see lots of threads on that can of worms already. It is indeed confusing: I suspect that when all the answers are in on this thread you'll be more confused rather than less. My comments below based on what seems to be consensus opinion, not on my first hand knowledge.

* Try not to leave the battery on charge once it reaches 100%. Some chargers cut out at that point, but many continue providing small charge current which is bad for the battery.

* If you don't regularly charge to the full you should do so once a month or so to keep the battery balanced.

* Don't let the battery get very low, though the BMS should protect it if it does.

* If you need to store for more than a week or so make sure charge is somewhere between 50-80%.

* I understand that on modern batteries partial charges take a partial toll on it's life; and that suggestions that a partial charge is as bad as a full one are based on experience with earlier battery technology.

I tend to charge to 100% when the battery is about 1/2 full, or when I know a longer ride may be coming up. That's convenient and I think/hope it won't significantly reduce battery life.
Very good. :) :) :)
Andy
PS. Having two batteries allows you to run one battery down to 10% or less and swap "on the road" with the other one, for the best life of both batteries.