Parasitic Drain---Basic Questions

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AFAustin
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Parasitic Drain---Basic Questions

Please help a guy (who had problems with high school chemistry) understand the basics of parasitic drain.

From a little quick reading, here is what I think it means when it comes to flashlights:

__Flashlights with electronic switches on them have to have some current flowing through the switch so when they’re pressed, they activate the light.

__Mechanical clicky and twisty lights have no parasitic drain – their circuits are fully broken.

I want to be sure I know which of my lights have parasitic drain. And I want the simplest method for dealing with it. Several have mention in the user’s manual for how to lockout the light by means of a certain number of clicks, etc. Frankly, I can’t remember the different instructions for all the lights and don’t want to have to look them up every time.

So, is the simplest overall method to just give a twist to the tailcap (or head) when putting away any flashlight with an electronic switch?

Thanks,

Andrew

Edited by: AFAustin on 12/13/2020 - 19:13
zoulas
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Your definition is pretty accurate. Best thing to do is un twist the tail cap half turn when storing them.

flydiver
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Turn it on. Unscrew the tail until the light goes out. No drain now. Should work with about any light.

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jon_slider
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unscrewing only works with anodised lights
copper, titanium, brass wont break contact by unscrewing a half turn

however, parasitic drain is not a big drain.. some lights can go for years before they kill a battery inside

imo people tend to think all parasitic drain is bad, but if it takes more than a year to kill a battery, I dont think it matters much.

I have many lights with electronic switches. They all work fine. I dont unscrew them. If I really dont plan to use a light for more than I year, I dont store it with a battery inside.

I suggest to people concerned about parasitic drain, that they take the time to learn how large the drain is, and how long it would take to drain a battery.

If you quantify the drain, you may learn it is insignificant. Zebra for example, tells us the parasitic drain on their lights is less than the self discharge rate of the battery. Nothing to worry about.

Yokiamy
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Yep, basically only an e switch has parasitic drain, or lights with lighted tailcaps.

What John said, it really depends on the light. Some will drain a cell in weeks, while others might do that in years.

I disabled the lighted tailcap of my Lumintop Tool lights, since they drained 14500 in a few weeks.

jon_slider
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Yokiamy wrote:
I disabled the lighted tailcap of my Lumintop Tool lights, since they drained 14500 in a few weeks.

I would do the same, however, that is not actually an eSwitch..

I would destroy the LEDs in the tailswitch of the AA Tool, IF I was to use 14500..

but I use Eneloop, which does not turn on the tailswitch LEDs. The tailswitch itself is mechanical, not electronic, so Zero parasitic w Eneloop.

the OP should specify which exact lights he has, that cause him a parasitic concern

AFAustin
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Thanks for the comments and advice.

Jon asked about the lights I have that cause concern. The ones with e-switches are:

Acebeam E10

Thrunite Neutron 2C V3

Sofirn SC31 Pro

Thrunite T10 II (1xAA)

Sofirn SP10S (1xAA)

I think all my others have mechanical switches (and no copper, brass or titanium bodies).

jon_slider
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AFAustin wrote:
Sofirn SC31 Pro

I googled Sofirn SC31 Pro parasitic drain and found this

you may need to spend some quality googling the others

another term for parasitic drain is standby drain

once we know the drain, we can learn to calculate how long it would take to drain the size battery in the light

maybe someone here can help confirm the calculation needed.. to determine how long the battery would last, at parasitic drain rate…

I think it goes like this.. battery is 3000mAh, divide by drain of 0.23mA (info from the video caption) =13,043 hours, divide by 24 hours = 543 days, div by 30 = 18 months…

iow, if you recharge the battery in your SC31 at least once a year.. the parasites wont hurt you. Smile

you can see from the video, that some people also know how to actually measure the drain themselves (Im not one of them)

I hope this helps point you in the right direction

AFAustin
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Thanks. In general, it doesn’t seem like a huge concern then.

Chicken Drumstick
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jon_slider wrote:
AFAustin wrote:
Sofirn SC31 Pro

I googled Sofirn SC31 Pro parasitic drain and found this

you may need to spend some quality googling the others

another term for parasitic drain is standby drain

once we know the drain, we can learn to calculate how long it would take to drain the size battery in the light

maybe someone here can help confirm the calculation needed.. to determine how long the battery would last, at parasitic drain rate…

I think it goes like this.. battery is 3000mAh, divide by drain of 0.23mA (info from the video caption) =13,043 hours, divide by 24 hours = 543 days, div by 30 = 18 months…

iow, if you recharge the battery in your SC31 at least once a year.. the parasites wont hurt you. Smile

you can see from the video, that some people also know how to actually measure the drain themselves (Im not one of them)

I hope this helps point you in the right direction

Thanks, I think that is a good example of why it is such a problem.

Lots of batteries are well under 3000mAh. Even 18650’s…. And of course that would be the assumption that it is fully charged when you put the torch away.

I suspect the reality is, lots of people might have a part used battery, say 3.9 or 4.0v (resting). If you leave it for 6 months….. even on a high displacement battery, it’ll mean it is mostly no good unless you go and recharge it. As it will be mostly flat by this time.

If it is something like a 14500/16340 then with only 500-700mAh you may well have ruined that battery.

jon_slider
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AFAustin wrote:
Thanks. In general, it doesn’t seem like a huge concern then.

that is my impression as well,

still, you asked a good question, and its always good to seek confirmation regarding specific lights

for example, I got rid of a Folomov C01 because every time I tried to use it, it was dead. From sitting on my nightstand for a week or two at a time (because I use so many other lights)

and as mentioned above, the AA Tool definitely has a problem on 14500.. but not on AA

My most used lights are Jetbeam Rotaries.. it took some time to locate parasitic drain info.. it ended up being slightly less than 0.03mA and that light can use a 700mAh 16340..

the math says it would drain the battery in 700 div by 0.03 = 2.7 years
thats a long time..

Chicken Drumstick wrote:
If you leave it for 6 months… you may well have ruined that battery.

I dont recommend storing a light for half a year, with batteries inside, but it wont ruin a protected battery. It is just unrealistic to expect a light that has been ignored for many months, to hold a charge indefinitely.

It would be better to store the batteries outside the light, imo.. and they should still be freshly charged when put back in service..

and, it is always prudent to have spare batteries, and a backup light Smile

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It would have been interesting if the supply voltage in that video had also been reduced to test at below ~2.8 VDC where Anduril's built-in low voltage protection is supposed to activate as I am curious if the parasitic drain would have stopped, decreased or remained the same.

 

I'm guessing it would have remained the same.

How many flashlights does a "real man" need?

None, real men are not afraid of the dark.

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If you don’t use flashlight for years why you care about it (some parasitic drain) ;)) It is possible to active fuse on attiny85 to switch off at 2.7v

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roostre wrote:
I’m guessing it would have remained the same.

your guess is the LVP does not turn off the switch, after 1.5 years sitting idle?

maybe you can find out if your guess is true, by asking TK about how anduril LVP works..

my guess is once LVP is triggered, the switch sees 0 volts, so the light wont work… until we install a fresh battery

roostre
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jon_slider wrote:
your guess is the LVP does not turn off the switch, after 1.5 years sitting idle? maybe you can find out if your guess is true, by asking TK about how anduril LVP works.. my guess is once LVP is triggered, the switch sees 0 volts, so the light wont work... until we install a fresh battery

Sorry if my post was not clearly understandable.

My concern was whether the low voltage protection provided at ~2.8 VDC by Anduril for the micro processors Anduril operates on would eliminate all parasitic drain on the battery so that the battery can never be discharged below a safe level and if the voltage supply in the video had been reduced to test at below ~2.8 VDC the answer to my concern would have been answered.

My guess is that once Anduril's low voltage protection is activated at ~2.8 VDC that the micro processor will no longer allow power to be provided to the main or aux LEDs (including the switch LEDs) but that the micro processor will still have a parasitic drain on the battery in order to determine when the battery's voltage is above the low voltage cutout or else how would the micro processor be able to differentiate between a freshly charged and low voltage battery and it would be this parasitic drain that would continue to discharge the battery to an unsafe voltage even with Anduril's low voltage protection activated.

Power to the micro processor is probably more a function of the physical hardware than of the Anduril software but I do not know how the various processors used with Anduril operate. It may be possible that the micro processors used for Anduril contain some built-in electronic circuitry that will not pass any power below a certain voltage.

How many flashlights does a "real man" need?

None, real men are not afraid of the dark.

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roostre wrote:
It may be possible that the micro processors used for Anduril contain some built-in electronic circuitry that will not pass any power below a certain voltage.

I believe that is correct
my understanding is that Low Voltage Protection is like a switch, that shuts off power from the battery, for all parts of the light, both head and tail.

this built in LVP is what allows Anduril to work with UnProtected batteries safely, by preventing overdischarge below 2.8v

I believe this LVP is also the reason there are no Anduril lights that run on AA batteries, whose voltage of 1.5v is too low to operate, given the LVP shutoff at 2.8v.

(Until someone feels it is profitable to design a circuit that can recognize the difference between a dying LiIon and a fully charged AA. This imo is why there is no AA/14500 Sofirn with Anduril.. even though it was discussed for a long time)

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Yokiamy wrote:
Yep, basically only an e switch has parasitic drain, or lights with lighted tailcaps. What John said, it really depends on the light. Some will drain a cell in weeks, while others might do that in years. I disabled the lighted tailcap of my Lumintop Tool lights, since they drained 14500 in a few weeks.

 

How did you do this, if I might ask? Any special tools (no pun intended) required? I'm on the fence as to whether or not I want to disable the LED's in my Tool's. As I use one of them as a "nightstand" light, for now I just back off the tail cap in the morning,  and crank it down at night.

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TIFisher wrote:
I use one of them as a “nightstand” light, for now I just back off the tail cap in the morning,  and crank it down at night.

LOL! Brilliant Smile

Tail Cap Glowing Blue – How to turn off? Tool AA 2.0

or you could just remove the 14500 and use AA
the tail does not light up on AA, only on 14500

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jon_slider wrote:

I dont recommend storing a light for half a year, with batteries inside, but it wont ruin a protected battery. It is just unrealistic to expect a light that has been ignored for many months, to hold a charge indefinitely.

It would be better to store the batteries outside the light, imo.. and they should still be freshly charged when put back in service..

and, it is always prudent to have spare batteries, and a backup light Smile


No harm storing lights with batteries in as a rule…… that is how they are backup lights Wink

But backup lights that drain the batteries are by definition flippin useless Sad

Given the choice, I’d much rather not have an electronic switch. There really seems few use cases to say they are truly better. The ramping is ok, but I’d still like a physical switch to turn it on and off. Then it simply is a non issue. Rather than fishing around looking for workarounds to solve a problem that doesn’t need to exist.

BTW – I hardly ever use protected batteries. Nearly all of mine are IMR’s… Smile

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Chicken Drumstick wrote:
BTW – I hardly ever use protected batteries. Nearly all of mine are IMR’s… Smile

I use unprotected IMR in my unprotected EDC

but I check and charge it every few weeks.

I dont leave any type of battery in a light for 2 years at a time
without doing a voltage check at least twice a year.

Even lights rotating through my storage case, some with partially used cells, get their batteries checked and charged every couple of months.

so to me, a parasitic drain measured in years, is not a limiting variable.

there are good reasons to choose mechanical switches, if multi year storage is a priority.. it just does not apply to my use case scenario

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jon_slider wrote:
TIFisher wrote:
I use one of them as a "nightstand" light, for now I just back off the tail cap in the morning,  and crank it down at night.
LOL! Brilliant Smile "Tail Cap Glowing Blue - How to turn off? Tool AA 2.0 ":https://budgetlightforum.com/node/71464 or you could just remove the 14500 and use AA the tail does not light up on AA, only on 14500
Thanks for the link! I keep a second Tool 2.0 in my work vehicle that's fitted with the mag tail cap to attach to the insides of metal cabinet machines I work on. I run NiMH in that one as I don't need the extra juice or lumens the 14500 provides, but at home or out and about after dark I'm diggin' the extra output and the rear clicky.

 

Sorry OP, didn't mean to hijack your thread.

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Lights with magnetic switches usually have a higher parasitic drain. A DV-S9 with magslider will drain a fully-charged 26650 in something like 3wks.

Then again, even (ironically) protected cells have a circuit that sniffs the voltage across the cell, and that’s parasitic drain. Granted, it’ll take a year or more, but they do drain the cell they’re mounted on, even if it’s sitting in a box and not a flashlight.

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jon_slider wrote:

so to me, a parasitic drain measured in years, is not a limiting variable.

With the 18650 lights this is more the case. But as I said earlier, if you have 14500 or 16340 lights, then it is a different ball game, as it isn’t years due to the much lower capacity of the batteries. Smile
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I wasn’t concerned about it until I got a Tool ti with blue lit tailcap switch.
I didn’t know it’d drain the 14500 down to 0V until I found out the hard way

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TIFisher wrote:

Yokiamy wrote:
Yep, basically only an e switch has parasitic drain, or lights with lighted tailcaps. What John said, it really depends on the light. Some will drain a cell in weeks, while others might do that in years. I disabled the lighted tailcap of my Lumintop Tool lights, since they drained 14500 in a few weeks.

 


How did you do this, if I might ask? Any special tools (no pun intended) required? I’m on the fence as to whether or not I want to disable the LED’s in my Tool’s. As I use one of them as a “nightstand” light, for now I just back off the tail cap in the morning,  and crank it down at night.

I opened the tail by unscrewing the retaining ring and popped off the LED’S from the pcb.
Assemble it (tighten it firm) and voila

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Chicken Drumstick wrote:
jon_slider wrote:
so to me, a parasitic drain measured in years, is not a limiting variable.
With the 18650 lights this is more the case. But as I said earlier, if you have 14500 or 16340 lights, then it is a different ball game, as it isn’t years due to the much lower capacity of the batteries. Smile

no, you are speaking in vague generalities.. I suggest you give a specific example

as I wrote regarding the RRT-01 above
that you dont seem to understand yet…
2.9 YEARS FROM A 16340

dont take my word for it, read it yourself:

selbuilt wrote:
For a typical… 750mAh RCR, this would translate into ~2.9 years before a fresh cell would be fully discharged… This is not a concern

again… 2.9 years from a 16340 in an RRT-01!!!

lionheart_2281 wrote:
I wasn’t concerned about it until I got a Tool ti with blue lit tailcap switch. I didn’t know it’d drain the 14500 down to 0V until I found out the hard way

IF you used a protected cell
and protection tripped, that is how you got a 0 Volt reading..

the protection circuit in the battery flipped the fuse, so the battery “seemed” to read 0 volts.. which actually happened at about 2.7volts.. the 0 volt reading on a Protected Cell, is not real.

and
the blue aux lights are NOT a parasitic eSwitch drain,
the switch is mechanical, there is no parasitic drain

the blue LEDs are actually Auxiliary lights. The instructions say to twist the tailcap to turn off the Aux lights. (this does not work on my all copper AA Tool).

I dont have 14500, maybe do a test.. do the aux lights on the tail turn off by unscrewing the HEAD of the light?

I do agree the blue lights on the tail of the AA Tool are a stupid idea, with much too high a constant ON power drain.

Or, use AA, and no blue tail lights to worry about.