How do you discharge

So how do you discharge batteries that you want to store?

I have some lights that have two batteries I rotate. When I feel the need to switch them sometimes it has not been used enough to get it down to 3.6V.

What is your method?

Following. Good to know some of the good habits flashaholics here maintain.

rigged up a 1 ohm (I forget the watt dissipation) resistor, battery carrier and a switch. Put battery in, flip the switch, monitor the voltage on the battery till it gets to 3.3 volts under the 3+ amp load. I tend to store mine at 30% of max charge for long term storage, ie months. This is for 18650s, i wont put my 14500 or 16340 under that kind of load. Those i just leave the flashlight on and periodically check the no load voltage.

Use the discharge function in my Opus BT C3100 at 1A for 18650 cells until it hits 3.6 to 3.7v.
For 16340, 14500 and 18350, I uses 0.5A

I just use a flashlight to take them down. Could be any one of several high amp users in my flock. Been doing this for years and seems to be the quickest way to get them down to resting voltage. And I have a herd of RC chargers that do that same job but a decent flashlight ends up being faster in the end. A quick check with a DMM and I know I put the cells away at the right voltage.

When I want to store an 18650 at 3.6 volts, I use my charger! It's a Nitecore Digicharger D4. It has a setting for LiFePO2 batteries that stops right at 3.6 volts.

Obviously, this is a two-step process.

1. Use battery in flashlight until voltage is lower than 3.6 volts.
2. Use charger to charge back up to 3.6 volts.

akhyar said:

Use the discharge function in my Opus BT C3100 at 1A for 18650 cells until it hits 3.6 to 3.7v.
For 16340, 14500 and 18350, I uses 0.5A

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I keep seeing this charger come up here, will need to check one out.

The discharge function can be set to stop at a certain amount or needs to be stopped manually?

KeepingItLight said:

When I want to store an 18650 at 3.6 volts, I use my charger! It's a Nitecore Digicharger D4. It has a setting for LiFePO2 batteries that stops right at 3.6 volts.

Obviously, this is a two-step process.

1. Use battery in flashlight until voltage is lower than 3.6 volts.
2. Use charger to charge back up to 3.6 volts.

Click to expand...

This is what I have been doing except have no LIFePO2 on my XTAR VC2 Plus so have to stop it manually. Of course my charge does not show voltage just a percentage of complete charge.

31% is 3.6V on my charger in case you was wondering.

HarleyXJGuy said:

I keep seeing this charger come up here, will need to check one out.

The discharge function can be set to stop at a certain amount or needs to be stopped manually?

Click to expand...

IIRC, it will discharge all the way down to 2.8v, so I normally remove the batteries once the display shows 3.6 or 3.7v

akhyar said:

IIRC, it will discharge all the way down to 2.8v, so I normally remove the batteries once the display shows 3.6 or 3.7v

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Ok then so not really an upgrade to what I have. Use my VC 2 Plus as a ups power pack and try and catch it at 3.6V. If I do not catch it and leave it till it cuts itself off at 3.10V so no danger of over discharge.

I am pretty sure I am being overly concerned with rotating fully charged cells out more often them is nessesary but I enjoy messing around with the charger and batteries.

HarleyXJGuy said:

Ok then so not really an upgrade to what I have. Use my VC 2 Plus as a ups power pack and try and catch it at 3.6V. If I do not catch it and leave it till it cuts itself off at 3.10V so no danger of over discharge.

I am pretty sure I am being overly concerned with rotating fully charged cells out more often them is nessesary but I enjoy messing around with the charger and batteries.

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3.1v is not over discharge, without splitting hairs, maybe 30-40% left in the tank at 3.6v , cell dependent........My mods work down to 3.3v so there is enough in the tank to supply 9a for 5-8s bursts.....

Most cells are rated at 2.5 or 2.7v min, so past that is over discharged and even then its not the end of the world...........as long as its not left for a long period, it will charge up fine!

3.6v is a nice V as it gives a good buffer, reduces the charging time back to 4.2v and is also a part cycle(not a full cycle). So again without getting anal, charging back up at 3.6v could be argued its 1/2 a cycle, cell may be rated at 300 cycles, so 600 part cycles .............many years of use from an $8 ish cell.........

Learn the light, before you know it you will be guessing the V before it goes on charge!!!

Remember that the 3500mah or 3000mah(cell dependent) is measured from say 2.5v to 4.2v which many will get no where near!!! So if a 3000mah is a good bit cheaper than a 3500mah cell, there is no real reason imho to spend the extra premium unless you use your cells right down. I know there is a little more to it than that, just keeping it simple(all be it a rough round the edges example).

So maybe your new light, use it and check the V after 30m of use, use again and so on, build up a rough idea of use time , then charge back up. Thats all i do, dont have time (nor enough interest to get really anal). I am interested in cells and chargers, no question there and kind of a little hobby in itself, but having a life and time restrictions lean me more to just using common sense and enjoying them. Yet to happen, but if i do ruin a cell, its not exactly like a big expense to replace........imo!

Dont worry about being overly concerned at the start, lots to take in, soon fall in place and you will just enjoy them for what they are..........high performance food for your lights

Most fun way of storing at 3.6v is using the light to achieve that nominal voltage

ven said:

Learn the light, before you know it you will be guessing the V before it goes on charge!!!

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This happened to me the other day with my oldest quality light, a SWM V11R. I was out back playing around.....I mean doing important stuff with it when I was like this thing is getting low.

Checked it and it was at 3.4V. Was pretty pleased with myself.