How Can I Test for Parasitic Drain?

recDNA

Flashaholic
Joined
Jun 2, 2009
Messages
8,761
I have a multimeter but I don't know how I can test drain with the flashlight closed and if open contact is lost so no dra?
 

Morelite

Flashlight Enthusiast
Joined
Nov 29, 2005
Messages
2,253
Location
Central PA
What light do you need to test?
If you can remove the tailcap put your test leads between the battery and the metal contact area of the tube. With your multimeter set on A or mA and your leads plugged into A or mA and common, put one lead on the battery's negitive contact and the other lead on the battery tube where the tailcap would normally make contact. While the light is off any reading you get is the parasitic drain.
 

recDNA

Flashaholic
Joined
Jun 2, 2009
Messages
8,761
What light do you need to test?
If you can remove the tailcap put your test leads between the battery and the metal contact area of the tube. With your multimeter set on A or mA and your leads plugged into A or mA and common, put one lead on the battery's negitive contact and the other lead on the battery tube where the tailcap would normally make contact. While the light is off any reading you get is the parasitic drain.

Der...makes perfect sense. I'm embarrassed. Thanks!

Fenix TK40, Fenix E20, Fenix LD01
 

Morelite

Flashlight Enthusiast
Joined
Nov 29, 2005
Messages
2,253
Location
Central PA
Not positive on the TK40, but the others definitely have no parasitic drain.

The TK40 does have a nasty parasitic drain, even the manual says "If you leave the flashlight unused for a couple of days, please unscrew the head 2.5 turns to prevent slow discharge of batteries."
 

recDNA

Flashaholic
Joined
Jun 2, 2009
Messages
8,761
The TK40 does have a nasty parasitic drain, even the manual says "If you leave the flashlight unused for a couple of days, please unscrew the head 2.5 turns to prevent slow discharge of batteries."

You'd think they could design a fix
 

Marduke

Flashaholic
Joined
Jun 19, 2007
Messages
10,110
Location
Huntsville, AL
Well, since "parasitic drain" is a feature of the design and not a flaw, why?

If you are storing your cells in the light long enough for it to matter, the cells don't need to be stored in the light even if it has no parasitic drain.
 

woodrow

Flashlight Enthusiast
Joined
Feb 7, 2006
Messages
2,027
Location
New Mexico
I was quoted that the TK40 would take about a year to deplete its nimh batts or 20 months to deplete lithium AA's. This is covered by HJK in the TK40 thread part three. Im not that worried about it after those numbers.
 

HKJ

Flashaholic
Joined
Mar 26, 2008
Messages
9,715
Location
Copenhagen, Denmark
I have a multimeter but I don't know how I can test drain with the flashlight closed and if open contact is lost so no dra?

It is rather tricky to do that, any light, with a tail switch, where you can just remove the tailcap and measure the current drain, will not have any parasitic drain. It usual has to be lights with the switch mounted on the head or with 3 connections from the battery tube to the head.
 

techwg

Flashlight Enthusiast
Joined
May 4, 2007
Messages
1,268
Location
United Kingdom
I was quoted that the TK40 would take about a year to deplete its nimh batts or 20 months to deplete lithium AA's. This is covered by HJK in the TK40 thread part three. Im not that worried about it after those numbers.

Im glad i don't have this light then. 20 months till complete drain may sound "ok", but when you considder your usage of the light, and a crucial need for light... If your batteries are not fresh, but "should" provide enough emergancy light even after months of non use, a paracitic drain may drain the batteries to the point of being useless.

If i am aware of a paracitic drain, i will simply not buy that light. It would have to be so small drain that it would take 10 years to drain the power, in order for me to even considder it. I heard that there is a light that has memory, yet no drain. I think that should be saught after by all manufacturors
 

HKJ

Flashaholic
Joined
Mar 26, 2008
Messages
9,715
Location
Copenhagen, Denmark
Im glad i don't have this light then. 20 months till complete drain may sound "ok", but when you considder your usage of the light, and a crucial need for light... If your batteries are not fresh, but "should" provide enough emergancy light even after months of non use, a paracitic drain may drain the batteries to the point of being useless.

If you know about the drain, you can always lock out the light, then it has no drain.

If i am aware of a paracitic drain, i will simply not buy that light. It would have to be so small drain that it would take 10 years to drain the power, in order for me to even considder it. I heard that there is a light that has memory, yet no drain. I think that should be saught after by all manufacturors

The drain has nothing with memory to do, only with the user interface. Keeping the power on, makes it possible to make more advanced user interfaces.

Some light also has a very low drain, LiteFlux is usual good and the OLight M30 is very very good.
 

recDNA

Flashaholic
Joined
Jun 2, 2009
Messages
8,761
Well, since "parasitic drain" is a feature of the design and not a flaw, why?

If you are storing your cells in the light long enough for it to matter, the cells don't need to be stored in the light even if it has no parasitic drain.

Would you want to try to install 8 AA's in that holder in the dark?
 

recDNA

Flashaholic
Joined
Jun 2, 2009
Messages
8,761
Well, since "parasitic drain" is a feature of the design and not a flaw, why?

If you are storing your cells in the light long enough for it to matter, the cells don't need to be stored in the light even if it has no parasitic drain.


Ya, I prefer a bezel ring to a memory function anyway. Only chose the Fenix due to readily available AA's in an emergency
 

Th232

Flashlight Enthusiast
Joined
Dec 25, 2008
Messages
1,064
Location
Sydney, Australia
Would you want to try to install 8 AA's in that holder in the dark?

Why not keep the batteries in the holder, then only install the holder when needed? There's definitely no parasitic drain in the battery holder itself. And if you drop it, easier to find one big holder rather than one (or more) AAs.
 
Last edited:

Nimravus

Newly Enlightened
Joined
Jan 8, 2006
Messages
21
Location
Canada
Keeping your light clean will avoid parasites. Rubbing alchool works well and helps keep the contacts clean also.

Sorry I couldn't resist.

Sounds like it's a simple enough way of doing this test.

Thank you.
 

recDNA

Flashaholic
Joined
Jun 2, 2009
Messages
8,761
Why not keep the batteries in the holder, then only install the holder when needed? There's definitely no parasitic drain in the battery holder itself. And if you drop it, easier to find one big holder rather than one (or more) AAs.

In a word...my wife. I want her to be able to use the light in an emergency and if there is more to it than on/off she won't listen when I try to explain it. I'm not knocking her...she's just anti-techie. Why she married a bio/computer/teckie nerd I'll never know!
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
It is rather tricky to do that, any light, with a tail switch, where you can just remove the tailcap and measure the current drain, will not have any parasitic drain. It usual has to be lights with the switch mounted on the head or with 3 connections from the battery tube to the head.

It's a little hard for me to parse your sentences above, but I've measured the parasitic current drain of an OpticsHQ multifunction tailcap using the technique described by Morelite in Post #2. Hardly tricky. Simply complete the circuit.
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
Why not keep the batteries in the holder, then only install the holder when needed? There's definitely no parasitic drain in the battery holder itself. And if you drop it, easier to find one big holder rather than one (or more) AAs.

Of course there are workarounds to the parasitic drain problem, but turning your fancy flashlight into a glorified stick seems to point to a bad flashlight design if that's what's required to use the light effectively. For me, the last thing I want to do is separate my power source from my light and then try to remember where all the parts are 12 months later, in the dark, in an emergency. Parts have a bad tendency to migrate.
 

Justin Case

Flashlight Enthusiast
Joined
Mar 19, 2008
Messages
3,797
Well, since "parasitic drain" is a feature of the design and not a flaw, why?

It could be a flaw, depending on what IC controller is used. The popular ATMEL Tiny13V PWM controller, for example, has a high parasitic drain on the order of 1mA in idle mode. But if you implement the right power saving features, you can get the drain down into the microamp range. So, IMO a high drain for a design that uses this controller is a flaw since one can program the chip to draw 3 orders of magnitude less parasitic current drain. If I really wanted to be hard on the TK40 design, I would claim that the high drain is definitely a design flaw since they selected the wrong PWM controller to begin with.
 
Top