Parasitic drain values?

robertsig · 2019-03-03T12:45:35.000Z

I'm reading several flashlight reviews and for those with electronic switches, sometimes the parasitic drain value is mentioned, like 22µA or 0.7mA etc. What I don't know is how much a given micro or milliamp value effects the drain on the batteries. I often read that it is "negligible", but that word means different things to people. To me negligible is 5+ years, but for others it could be less than a year.

So that we don't have to do the math each time, can anyone give us a calculation chart of common batteries and µA values so we know how long is long? Maybe a spreadsheet where you can plug in the values and cross reference against battery types to actually know how much drain a given flashlight has?

I'm not that person to do it!...only to suggest it. Even among the experts, I've seen people mistake their math. Perhaps we can get a consensus.

bmengineer · 2019-03-03T13:24:20.000Z

Just divide the cell capacity by the current.

3500mAh / 0.022mA = 159091 h

WalkIntoTheLight · 2019-03-03T13:42:32.000Z

Yeah, we’re not talking General Relativity math. Just get out your calculator and press the divide button. Easy.

robertsig · 2019-03-03T17:11:23.000Z

Easier not to do the math each time, but I suppose I can. I'll make a spreadsheet..

toddcshoe · 2019-03-03T18:12:24.000Z

I think what would be more useful is lights with a abnormally high parasitic drain. If the drain takes more than a few years to drain a cell is that really a problem for some people? I don’t think I have ever left a cell in a light that long. I guess some people might but that seems highly unlikely with this group on BLF.

I know there are some lights that can kill a cell in a few months. Now that is good information to have. I don’t keep flashlights with those kind of drain rates. I don’t care how nice it is, it serves no useful purpose to me if it kills itself every other month.

Lightbringer · 2019-03-03T18:28:53.000Z

Dunno about anyone else, but if I know I’m not going to be regularly using a light, even with a tail-clicky, I do a TCLO to keep it from being accidentally turned on.

Give it a ½-turn… how hard is that?

Jack_Kellar · 2019-03-03T19:34:35.000Z

toddcshoe:

I know there are some lights that can kill a cell in a few months. Now that is good information to have. I don’t keep flashlights with those kind of drain rates. I don’t care how nice it is, it serves no useful purpose to me if it kills itself every other month.

No Nitecore for you then, Todd.

jon_slider · 2019-03-03T19:52:08.000Z

here btw is a list of lights with Standby or Parasitic current Drain … not because I avoid them, just because I was curious

since I charge the batteries in my EDC lights every week or two, a light with a 1 year parasitic drain does not concern me

for lights that are stored for emergencies… maybe better to store the battery outside the light, or use physical lockout

toddcshoe · 2019-03-03T20:28:19.000Z

Jack Kellar:

toddcshoe:

I know there are some lights that can kill a cell in a few months. Now that is good information to have. I don’t keep flashlights with those kind of drain rates. I don’t care how nice it is, it serves no useful purpose to me if it kills itself every other month.

No Nitecore for you then, Todd.

Do they have bad drain? The only Nitecore lights I have had are the Tini and Tip. They always come on in my pocket so they are always dead anyway.

robertsig · 2019-03-08T00:25:04.000Z

Lightbringer:

Dunno about anyone else, but if I know I’m not going to be regularly using a light, even with a tail-clicky, I do a TCLO to keep it from being accidentally turned on. Give it a ½-turn… how hard is that?

Well I use BLF not just to buy lights for me, but to research lights as gifts for F&F. That being said, even as somebody in the know, I try to avoid any flashlights with substantial standby drain. I'm also not a fan of lights with complicated UI's. It's easier for me to use the same lights I recommend to others.

On a personal note, I think it's completely silly that flashlights need 6 modes with 8 steps and various blinky options. Not once in my life, ever, have I come remotely to needing an SOS flashlight. And if I put myself into that situation, I'd have a light dedicated to do that. I don't need my EDC to do that.

BlueSwordM · 2019-03-08T00:43:17.000Z

Most BLF lights have extremely low standby drain, and BLF lights can be set to have very simple UIs, like a simple 4 mode with moonlight and hidden blinkies when needed.

jon_slider · 2019-03-08T01:05:56.000Z

robertsig:

I try to avoid any flashlights with substantial standby drain.

how substantial are we talking about here?
like, drains the battery in a year, or a week?

.

BlueSwordM:

extremely low standby drain

How low is extremely, drains the light in a year, or 3 years, or?

.

just looking to quantify the drain in calendar time…
the mAh numbers mean little to me (how little you ask? well, meaningless really )

BlueSwordM · 2019-03-08T01:16:52.000Z

GT Mini: 20uA in lockout(max value I’ve seen with my sample: 22uA, min value: 15,96uA)

3,0Ah/0,00002A = 150 000h = 17,1 years.

Basically, the cell will have self-discharged completely before the light drains it noticeably.

BLF Q8:

12,0Ah/0,00002A = 68 years.

Again, this is very low, and lower than the cell’s self-discharged, and can be considered negligible.

Still, if you want the absolute best, get a tailswitch only light.

But e-switches can now fight on the same level of standby drain.

Pete7874 · 2019-03-08T02:13:26.000Z

jon_slider:

here btw is a list of lights with Standby or Parasitic current Drain … not because I avoid them, just because I was curious

Link not working.

ChrisGarrett · 2019-03-08T02:21:15.000Z

BlueSwordM:

GT Mini: 20uA in lockout(max value I’ve seen with my sample: 22uA, min value: 15,96uA)

3,0Ah/0,00002A = 150 000h = 17,1 years.

Basically, the cell will have self-discharged completely before the light drains it noticeably.

BLF Q8:

12,0Ah/0,00002A = 68 years.

Again, this is very low, and lower than the cell’s self-discharged, and can be considered negligible.

Still, if you want the absolute best, get a tailswitch only light.

But e-switches can now fight on the same level of standby drain.

That is the important part—parasitic drain in quality lights is less than the self discharge rate of quality cells. It’s practically a non issue today.

Chris

jon_slider · 2019-03-08T03:45:01.000Z

Pete7874:

jon_slider:

here btw is a list of lights with Standby or Parasitic current Drain
Standby/parasitic current drain … not because I avoid them, just because I was curious

Link not working.

thanks
fixed:?
https://lygte-info.dk/info/standbyCurrent%20UK.html

BlueSwordM:

GT Mini: 20uA in lockout(max value I’ve seen with my sample: 22uA, min value: 15,96uA)

so 3000mAh battery, 20uA drain, 17 years
50uA drain from a 1200 mAh 18350 = 2.72 years?
or
50uA drain from a 700mAh 16340, 1 year 7 months?

Lithium primaries are a better choice for lights that dont get used for months at a time, imo, and would last 3 years ?w a CR123 draining at 50uA

ChrisGarrett:

That is the important part—parasitic drain in quality lights is less than the self discharge rate of quality cells. It’s practically a non issue today.

how much time do you think is long enough to be a non issue?
how often do you suggest rechecking batteries on stored lights?

If the new RRT-01 50uA standby drain might last 1 1/2 years on a 16340
do you consider it useful for EDC?

BlueSwordM · 2019-03-08T03:33:49.000Z

Damn. Where did you find a 45625Ah 16340 for the RRT-01?

I’d like to buy your nuclear fission powered 16340.

jon_slider · 2019-03-08T03:36:25.000Z

lol
I told you the numbers were greek to me

help!

I give you data, you give me math?
50uA drain from 1200mAh… how long will it last?

BlueSwordM · 2019-03-08T03:38:42.000Z

@jon_slider

If the new RRT-01 draws 50mA… for 1,5 years…

That’s why I said such a huge number

At 50uA, the cell will last:

1,2Ah/0,00005A = 2,73 years.

You’re good at math don’t worry.

jon_slider · 2019-03-08T03:51:41.000Z

aargh, fixed, thank you
I suck at power of 10 math nomenclature… LOL

so, does the RRT-01 have a “reasonable” or even, “trivial” parasitic drain if it pulls 50uA of those power of ten units you were talking about, out of a 16340, full of 700mAh of those other little power of 10 units you were talking about?

and
I would like to buy a few decimal places please… lol