Best way to maintain AIW 18650 batts long term?

[infinitium]

Hi guys, I just got my paws on a TK12 R5 w/AIW 18650 batt... I don't use my light often (maybe 1x-2x/month for 10 mins per time)... what's the best way to ensure I manage to keep my batts at optimum performance?

Also, with the AIW 18650 rechargeables, should the practice in recharging these be - I need to always ensure I fully discharge the batt before I charge 'em up to 100% again?

 

[HarveyRich]

Hi infinitium,

Welcome to the forum. First, the post is likely to be moved to the battery section by the mods since this is strictly a battery question. Second, although there are many here who know much more than I, my understanding is that li-ion batteries (AW, I assume you're saying) are better served for the long run when not fully charged--charged to say 4.0 - 4.1 V) and recharged when only partially discharged, unlike NiCd batteries, which should be fully discharged since they get a memory effect. NiMH rechargeables can be fully discharged or partially, but I've read that they last longer if recharged before full discharge also. You can recondition them, though by going through several full discharge cycles first. If you overdischarge a li-ion cell, you will kill it. That's why PCB overdischarge and overcharge protection is built into many of them.

 

[FroggyTaco]

Per AW's sales thread:


"Please keep the voltage of all LiIon batteries above 3.8V for healthy storage. Recharge as soon as possible when you have run them down. Storing a depleted ( less than 3.6V open voltage ) battery may damage/ shorten life/cycle permanently."

Also storing in the refrigerator in a baggie is a good idea as well.

 

[march.brown]

Hi guys, I just got my paws on a TK12 R5 w/AIW 18650 batt... I don't use my light often (maybe 1x-2x/month for 10 mins per time)... what's the best way to ensure I manage to keep my batts at optimum performance?

Also, with the AIW 18650 rechargeables, should the practice in recharging these be - I need to always ensure I fully discharge the batt before I charge 'em up to 100% again?

I have three Solarforce L2 torches that use a 18650 battery ... On full power the battery lasts two and a half hours continuous ... If I was to only use it for 15 minutes a month , it would be ready to be re-charged about every 9 or 10 months ... If I used it for 20 minutes per month it would need to be charged every seven or eight months.

Ideally you need to measure the battery voltage as it will be fully charged at 4.2 volts and fully discharged at 3.6 volts ... I would re-charge the battery at about 3.8 volts when it has still got 40% charge left in it ... So really in my case it would need charging every six months or so if it had the same use as yours does.

The big advantage of the 18650s is that you can top up whenever you want with no problems as long as they come off the charger at 4.2 volts maximum.

If you use protected 18650 batteries , the light will turn off on its own when the battery voltage gets too low ... Ideally you should have charged the battery before this happens though , otherwise you will be in the dark without a light ... Most people have an every-day-carry torch (EDC) and my preference is for one of the iTP torches ... I have iTP A3s (AAA) and iTP A2s (AA) which will fit on a keyring or clip in a pocket ... After much debate , I now have an iTP A3 on each of my two keyrings, and an A2 clipped into a pocket ... Can't have too many torches.

The Solarforce L2 is a great "dog-walking" torch ... I can get three dog walks (in the dark) per charge.
.

 

[psychbeat]

yeah- I just charge mine before I use em and dont really worry
about trying to keep em at a certain voltage- theyre pretty tuff
batts and will probably last a few years depending on how much you
use them. + replacement of batts is pretty cheap compared to how
much we spend on lights etc

if you run them down really low then recharge them as soon as
you get a chance but I wouldnt agonize over it too much-
unless yer into that kinda thing

 

[infinitium]

super... very helpful info. thanks so much guys!

 

[jhc37013]

I own a bunch on different Li-Ion and the ones that I don't use that often I top off every month or so just to keep it above 3.6v. If you have just a few you can just use a meter and charge as necessary but I have many so I just have a monthly or bi-monthly chargeathon.

 

[DM51]

Moving this to the Batteries section...

 

[bstrickler]

Maybe, since you rarely ever use it, you should consider getting primary CR123 cells. They should last you plenty long enough, and then you can keep the AW with the light, so when you know you'll need longer runtime, you can just pop the AW in, and put the 123's where you kept the 18650.

~Brian

 

[jasonck08]

It's best to store them at about 40% capacity which is around 3.7-3.8v.

It's never best to store them at very low or high charge levels.

 

[Battery Guy]

It's best to store them at about 40% capacity which is around 3.7-3.8v.

It's never best to store them at very low or high charge levels.

Right on target!:thumbsup:

The higher the state of charge, the faster a lithium-ion cell degrades. So from that perspective, you want to keep your lithium-ion cells fully discharged...

BUT...

If a cell is overdischarged, then you can do permanent damage that will lead to performance, reliability and maybe even safety issues.

So to mitigate against unintentional over discharge (via either self-discharge or discharge through leakage current in a circuit), you don't want to store a lithium-ion cell fully discharged. This is why manufacturers always recommend that you keep your lithium-ion cells charged up. They are trying to minimize the chance that you will fully discharge your battery in a light, then put it in a drawer and forget about it for a few months, because doing so could easily result in an over discharged lithium-ion cell.

Therefore, the compromise is to store lithium-ion cells at a moderate state of charge. I typically recommend storing lithium-ion cells removed from the light, at a 20-30% SOC (3.7V).

Cheers,
Battery Guy

 

[Duglum]

It's best to store them at about 40% capacity which is around 3.7-3.8v.

It's never best to store them at very low or high charge levels.

Right, ~40% and in the Fridge. See also: http://www.batteryuniversity.com/parttwo-34.htm