LED flashlights use any power when not on?

[passive101]

I'm simply wondering how long a set of 2 CR123As or a single AA would last in a flashlight. I know the lithiums have a 10 year shelf life. How long would they last in a flashlight?

For reference I'm ordering a Quark 2x123A and considering a AA light.

If they do use any power while off would an Alkaline or Lithium discharge slower?

 

[Lynx_Arc]

power drains less than a milliamp will not effect lithium any different than alkaline batteries. If you are going to let a light sit more than 6 months without checking it I would recommend taking the batteries out altogether.

 

[yellow]

if a light has a mechanical switch, there should be no drain at all
(very very small but possible chance of parasitic drain, check for that)

an electronic switch (= a monentary button) will drain the batts and thus such a light is no good idea to leave ready to use. At least unscrew the tailcap till there is no connection any more.
(example for such a light: Streamlight Argo HP, the only one with such a switch I own)

 

[Justin Case]

power drains less than a milliamp will not effect lithium any different than alkaline batteries. If you are going to let a light sit more than 6 months without checking it I would recommend taking the batteries out altogether.

1 mA draw IMO is excessive. Assuming your typical CR123A capacity of 1400mAh, a 1mA draw corresponds to 24mAh. That gives about 60 days shelf life (excluding any actual flashlight usage, which will shorten the life even more), which I think is very poor since the shelf life of a bare CR123A is about 10 years.

 

[kramer5150]

Any light that uses a switch that breaks conduction when off will not drain. How long a cell will last in a light like this will depend on the self discharging characteristics of the cell.

I have had AA alkalines last as little as 3-4 days before they leaked, at that point their charge holding capabilities are a moot point. Other Alkalines I have had for close to a year without problems.

My unprotected RCR123 cells (DX:2086) drop from 4.2V to 4.08V in about 2 months, sitting indoors on my desk.

You should also note that the protection circuit in Lithium-ion cells also draws current.

 

[Justin Case]

At least with AW's protected cells, the protection circuit draws on the order of microamps. If we use the high value of 6 uA, that gives 144 uAh per day drain. For a typical CR123A capacity of 1400mAh, that gives about 9700 days shelf life (ignoring any other sources of discharge), or 26 years.