Batteries and stress - What do you do?

So, do we just accept the fact that we are hard on our batteries or do we try to go easy on them? Should we care?

The way I look at it I want as full of battery as possible in my flashlight or at least available to put in when I need it. Full charge = brighter light and longer run time.

However, to get the most life out of a Lion they recommend storing at 40%. I don't want to put a 40% cell in my light when I need it and I have a slow charger. Therefore, I tend to keep my batteries full. Guess they won't last as long but I look at my laptop and a couple of years is not out of the question even with such abuse. $6 or so a cell on the flashlight is much easier to take than the $50 or so on the laptop.

What do you do?


Well , that's life .. The higher the performance of the flashlight , the more stress imposed on the battery , the shorter its life cycle ..

If you use a charger that takes a long time [ low charge current ] this may help ..

The number one thing , = Initial cell quality .... There is no getting past this

If you buy cheap batteries , they may test well to begin with , but come back and test again 12 months latter , and how did they do ?

So the better the battery to begin with , the longer its life cycle ...

Some of my 18650 have begun to degrade after 3 months of use , some died after 6 months , and one died after 12 months , and that sort of thing is really a no no for multi cell lights , you test , you match , only to find 6 months latter that one cell has seriously degraded and no longer comes close to being a match to the other ... yikes

Welcome to the Li-ion world . Its interesting to say the least . And the more you want to understand , the more tools you need to measure and probe ...

I think old4570 hit the nail on the head.

I have a bunch of batteries and have found the cheaper cells die pretty fast no matter what you do to them. My trustfires and Ultrafires where ok performers when new but they went down hill pretty fast. Some of them where down to 1/2 their capacity in just 1 year.

Some of my higher quality cells where within 40-50mah after the same period. Basically what I do is put all my batteries in rotation. When their not in a flashlight their at 3.7-3.8v I don't know if it really helps any but I think its better than just having them sit for months on end.

At first, I bought the cheapest batteries BUT I also bought several kinds of flashlights, like 16340, 10440, 14500 -based lights.

It was a good decision IMO, because now I´m more concentrated on 14500 and 18650, some 18350. Otherwise almost no li-ion usage on other sizes ATM. So, it´s not a bad thing that some of my oldest cells are already gone, they did their job long enough. (10440)

Now when I know what I use the most, I buy better ones.

On storage voltage:

I have an option in my Imax B6, to set batts to storage volts but I never use it. They are always either full and waiting to get used or standing by inside a light in use or waiting to get used.

When I need the light, I want it full. I have quite few spare batts, so not ruining many of them anyways.

By the time your batteries are getting worn out you'll be wanting to upgrade them with the latest and greatest anyway.

Don't sweat it. Keeping them charged is fine and you just need to accept a little degradation. The best advice I could give is to only buy as many as you absolutely need. Something better is always just around the corner.

The 40% recommendation is primarily for long-term storage, since a fully-charged Li-Ion loses ~20% capacity per year at room temperature, but only a few percent at 40% state-of-charge. That’s not self-discharge, it’s actual reduction in mAh rating (i.e. a cell which measures 2000 mAh new will have only 1600 mAh after sitting fully-charged for a year).
But you can have the reduced capacity loss of 40% charge with a fully-charged battery – just stick it in your refrigerator (not freezer!).

Good advice until you find a great deal like the rev Jim batteries …then you buy twice what you need and charge them fully and don’t worry about it at all …:slight_smile:

Almost on topic- if I use a TR 801 as a glove box/emergency light for my car- how long will a fresh 18650 last if not in use?

In other words in 3 months if I need to use the light to change a tire etc. will the 18650 still hold a charge or do you need to top them off every so often?

Thats a tough one ...

It depends on the individual cell , every six months or so I charge all my batteries ...

A few are depleted , most are around 3.8v to 4v , some are 4.15ish , a small number might be 4.17 or better ...

If you want to charge a battery , then put it away , buy quality ...

Also the glove box may be subject to extreme temps , Hot - Cold , bad news for the Li-ion ... as it wants stable temps on the cool side to maintain charge .

You may wish to buy a AA light , and store it in the glow box with a 4 pack of AA's rather than Li-ion ...

I only just remembered today the flashlight in the trunk of my car , its been there at least 12 months , might be time to change the AA's

I turned it on and it worked ,

Flashlights are a crossover hobby for me, stemming from my love of RC, firearms, and batteries (im obsessed with batteries. lol). anyway, I've been surprised by what people consider an abusive environment for these 18650s. I have a 11.1v 2100mAh lipo pack I've pulled 600 watts out of continuously until its "dead" (80% discharge) through hundreds of cycles. Thats hovering around 25C discharge rates I think. And then for my big helicopter I have a 10 cell LiFe4 pack made from A123 26650 cells that has pumped out over 1500 watts at times or 19-20C and its done it for many many cycles as well. These 2-3C discharge rates should be cake, but I guess the 18650s are designed for lower amp jobs.

Is anyone putting together high amp lights with the A123 26650 cells? those would seem to be the go-to cell for high current jobs.

Even a triple XML wouldn’t take advantage of the current capabilities of an A123 26650. We just don’t need that much power and the capacity is far less than a LiMn 26650. I use the 18650s all the time and they are fantastic. What I would love is an A123 14500! :slight_smile: