18650 storage question

HI. Please don`t rip my head off if these questions were asekd before. I looked but couldn`t find a direkt answer .

I just bought a set of AW`s 18650 for my two UF W-400`s. I plan to have them in my cars as emergency light.

1.st question: do i neeed to recharge them every tvo, three or six months?

2nd.: does it damage the 18650`s to have them stored fully charged?

3rd: is is save? I read the thread about the Li-ions going off in the toolbox. If this happens in my car while driving on the motorway it gets dangerous. i know that AW has good quality but i must admit that i am a littlebit concerned.

Thank you all in advance - and thank you all for this incredible forum!

Li-ions display very low self-discharge ~5% per month according to sources I've read. As for what charge to store them at, I've read anything between 40 and 60% is better to prolong cell life than 100%. If one started at 60% and wanted to keep them there, a recharge every 5%*4 months (20%) will keep them up in that range. Keep in mind that from the date of manufacture, Li-ions lose 20% capacity per year no matter how they're used, it's just a function of the chemistry. (If my sources are correct of course)

If it were me, for an emergency light, I'd just keep it fully charged and check it every 6 months, because in an emergency you won't really care about the life of your cells, you want that sucker to run as long as it possibly can.

A 18650 powered light is not the best for emergency stand by. A primary powered light is best. I would use a Fenix L2d with lithium AA's or any 123 lithium cell flashlight. Primary lithiums have a Long, Long shelf life with very long run times. You can just store these type lights away for about 10 years! Thats what I'd do.

Hello Barnefko,

Welcome to CPF.

The best way to prepare your light that uses an 18650 cell for long term emergency storage is to charge the cell up, and then run it for awhile. You are trying to get the battery voltage to be at around 4.05 - 4.10 volts. Run the light for a few minutes, take the cell out and let it rest for around 15 minutes, then measure the voltage.

The reason for this is to allow the chemistry to respond to changes in temperature during storage, but still be charged enough to give you adequate runtime if you need to use it.

You can check the voltage of the cell from time to time. When it drops below 4.0 volts, you can charge it back up a little. Make sure that you are checking battery voltages at room temperature. If you check it under cold or hot conditions, your voltages will be a little off.

Plan on replacing the cell every 5 years. You may still have some use left in the cell, but it may not be suitable for "emergency" use.

Tom

wkoukios said:

A 18650 powered light is not the best for emergency stand by. A primary powered light is best.

Click to expand...

I can't argue a basically common sense statement such as that, but I'll add that I actually do have a "plan" that involves the use of 18650's as emergency power.
What I do is the basics whereby I make sure that all my 18650's that are in my "full charge" case have been charged within the last 6 months at most. That's a reasonable period of time to still expect them to still have quite a charge left.

However, my "plan" revolves around the fact that in my location, I rarely lose power for more than maybe a few hours up to most of a day.
So what happens is that the 18650's have always been enough to get me through that period even if they didn't have a completely full charge due to storage loss (up to that 6 months).
At the same time, the rest of my "plan" is that I keep approximately 50 to 60 CR123's for use as backup "just in case".

So it is possible to rely on 18650's as backup batteries, but having backups (CR123's) to the backups (18650's) is also a good idea which fits in with your common sense statement.

storing 18650 batteries

hi guys,

what is the proper way to store 18650 batteries over a certain period of time.
my 18650 flashlight broke and my batteries are gathering dust at the moment.
any recommended way of storing the batts?
do i need to keep them fully charged after a few weeks or months?

i want them in tip top condition once i can get a new flashlight

thanks

Re: storing 18650 batteries

ya just put them in your RC charger and select the "Storage" option, it discharges/charges them to about 3.8v Resting voltage.
the idea being to get them to about 40-50% before storage. If they are old and self discharging , just toss them after storage they wont be any better.
if they are good batteries they will store fine.
depending on the quaility of the battery and the time you will store it, you might not want to store it at all, been there done that, storing cheap china trash is just a waste of effort because when you go back to get it its not worth all the work you did to store it. (not to mention that they are volitle items that were stored)