How Can I Test for Parasitic Drain?

[HKJ]

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.

How did you do that, the tailcap is not even included in the circuit in post #2?

Anyway, it is very uncommon that the tailcap is the reason for any drain.
The methode from post #2 can be used on NiteCore D10 and EX10, but not on LiteFlux and NovaTac, because they uses 3 connections.
With the Fenix TK40 and EagleTac M2, you have to make two connections between the battery container and the head of the flashlight.

 

[Justin Case]

I applied the same complete the circuit concept as in Post #2, not the specific procedure outlined in that post. Sorry about the confusion. I connected a jumper between the tailcap center spring and the battery terminal. I put my DMM between the flashlight tube (on some non-anodized, bare metal) and the outer contact ring in the tailcap. Easy.

For the OpticsHQ tailcap, it isn't the tailcap per se that is the problem. It is the electronics that are located in the tailcap. Of course, the electronics can be located elsewhere besides the tailcap.

 

[HKJ]

I have been busy writing an article about what flashlight has standby drain, at the current time it is only in danish, but I will probably translate it to English when it is finished.
If anybody want a preview, it can be read here. I have calculated the expected lifetime of batteries with the actual standby drain, but ignoring any self discharge of the batteries.

 

[wapkil]

I have been busy writing an article about what flashlight has standby drain, at the current time it is only in danish, but I will probably translate it to English when it is finished.
If anybody want a preview, I have a google translated version here.

I looked at the results for Zebralight and saw that you measured 66uA for H60. Have you performed more advanced tests or simply connected a DMM to measure it? I don't have an H60 but measured my H501 and it showed ~1.5uA with a simple DMM test. I thought this result is correct since it was consistent with Zebralight claim of <1uA for H60 (they don't give that value for H501). Now I'm wondering whether my DMM test was not accurate or the H501 actually has such a low consumption while the H60 has more that 60 times larger than claimed...

 

[ZebraLight]

I looked at the results for Zebralight and saw that you measured 66uA for H60. Have you performed more advanced tests or simply connected a DMM to measure it? I don't have an H60 but measured my H501 and it showed ~1.5uA with a simple DMM test. I thought this result is correct since it was consistent with Zebralight claim of <1uA for H60 (they don't give that value for H501). Now I'm wondering whether my DMM test was not accurate or the H501 actually has such a low consumption while the H60 has more that 60 times larger than claimed...

While the drain of the H60 is listed as <1uA in the spec, it is actually WAY below that. The H501 circuit is different in that the DC/DC converter has to keep working to boost the 1.5V battery source to a voltage that can power up the CPU even when the light is Off. Both the DC/DC converter and the CPU contribute to the drain. However, we managed to cut the current drain to the 1.5uA range, very low compare to other electronic pushbutton based flashligts.

 

[HKJ]

I looked at the results for Zebralight and saw that you measured 66uA for H60. Have you performed more advanced tests or simply connected a DMM to measure it? I don't have an H60 but measured my H501 and it showed ~1.5uA with a simple DMM test. I thought this result is correct since it was consistent with Zebralight claim of <1uA for H60 (they don't give that value for H501). Now I'm wondering whether my DMM test was not accurate or the H501 actually has such a low consumption while the H60 has more that 60 times larger than claimed...

My test was done with a DMM. I did not publish the value for H501 because it was a bit strange, it is very low (i.e. below 1uA) and then has jumps to a higher value for a short time. The H60 may work the same way, but never get to the low current part, due to series resistance in my meter.
I will do some more measurements on the Zebralights and see if I can get closer to the official value.

 

[HKJ]

While the drain of the H60 is listed as <1uA in the spec, it is actually WAY below that. The H501 circuit is different in that the DC/DC converter has to keep working to boost the 1.5V battery source to a voltage that can power up the CPU even when the light is Off. Both the DC/DC converter and the CPU contribute to the drain. However, we managed to cut the current drain to the 1.5uA range, very low compare to other electronic pushbutton based flashligts.

I have checked the H60 again, with two different meters (on of them is a Fluke 189). My H60 is from the first batch, maybe Zebralight has changed it later?
I also measure the H501 at about the 1.5uA.

 

[wapkil]

My test was done with a DMM. I did not publish the value for H501 because it was a bit strange, it is very low (i.e. below 1uA) and then has jumps to a higher value for a short time.

I checked and my DMM also sees these current jumps. The maximum value is almost 1mA (887uA) but the DMM is able only to see the current pulses with the duration of at least 0.8ms. It seems that one would have to use a scope to see how the current really looks like. The averaged value as reported by the DMM (so in this situation with an unknown accuracy) is 1.5uA though.

 

[HKJ]

I checked and my DMM also sees these current jumps. The maximum value is almost 1mA (887uA) but the DMM is able only to see the current pulses with the duration of at least 0.8ms. It seems that one would have to use a scope to see how the current really looks like. The averaged value as reported by the DMM (so in this situation with an unknown accuracy) is 1.5uA though.

I have put the 1.5uA value in for H501 now and also translated the article to English (Link in first post has been updated).
But the H60 is a mystery, there is not reason for it to use 66uA, when H501 only needs 1.5uA.

 

[wapkil]

While the drain of the H60 is listed as <1uA in the spec, it is actually WAY below that. The H501 circuit is different in that the DC/DC converter has to keep working to boost the 1.5V battery source to a voltage that can power up the CPU even when the light is Off. Both the DC/DC converter and the CPU contribute to the drain. However, we managed to cut the current drain to the 1.5uA range, very low compare to other electronic pushbutton based flashligts.

Thank you for the answer ZebraLight. It's good to hear that the parasitic drain of the H501 is as low as I measured. With the drain orders of magnitude lower than the self discharge of NiMH batteries I don't have to worry about it. I don't need the lock-out the light to eliminate it and I even informed other CPF members that I think it's not necessary. Good to know that I was right.

I think that you could place the information about the H501 parasitic drain in the specification on your website. I couldn't find it there. Perhaps there could be an explanation that this drain makes the lights functionally equivalent to the lights that exhibit no drain at all because of their construction.

Can you comment on the current pulses that HKJ and I saw measuring the current with our DMMs? They seem to be short but almost a thousand times higher than the average consumption so I wasn't sure if the value measured by the DMM is correct.

 

[Justin Case]

I have been busy writing an article about what flashlight has standby drain, at the current time it is only in danish, but I will probably translate it to English when it is finished.
If anybody want a preview, it can be read here. I have calculated the expected lifetime of batteries with the actual standby drain, but ignoring any self discharge of the batteries.

To add to your list for your article:

SureFire 12ZM, 3P, 6P, 9P, 6R, 8NX, L4, G2 all have zero parasitic drain. I"m sure there are other SureFires.

 

[cave dave]

With the drain orders of magnitude lower than the self discharge of NiMH batteries I don't have to worry about it. I don't need the lock-out the light to eliminate it and I even informed other CPF members that I think it's not necessary.

I think the drain is irrelevant because lock out on the H501 is virtually mandatory. Otherwise the slightest bump will turn the light on in your pocket or pack. It will most likely turn itself on in Max and drain your battery in less than 2 hrs.

The only place I wouldn't worry about it turning itself on for bedside
nightstand duty, but I think its good practice to always turn the H501 off by unscrewing the tailcap instead of using the switch.

 

[wapkil]

I think the drain is irrelevant because lock out on the H501 is virtually mandatory. Otherwise the slightest bump will turn the light on in your pocket or pack. It will most likely turn itself on in Max and drain your battery in less than 2 hrs.

The only place I wouldn't worry about it turning itself on for bedside
nightstand duty, but I think its good practice to always turn the H501 off by unscrewing the tailcap instead of using the switch.

The discussion I was referring to was specifically about the parasitic drain and the lack of necessity to eliminate it.

I do agree that it is generally good practice to lock out the H501. I don't see it as mandatory though. One of my zebras usually sits on my desk or stands near the bed. I don't bother to lock it out - I don't see the need to.

The one I frequently take outside is modified with a tailcap glued on top of the head:



It no longer turns on "by itself". If it goes to the backpack, I lock it out but I usually don't do it if it's in my pocket.

 

[HKJ]

To add to your list for your article:

SureFire 12ZM, 3P, 6P, 9P, 6R, 8NX, L4, G2 all have zero parasitic drain. I"m sure there are other SureFires.

I believe that nearly all SF has zero drain, the exception being the Titan and the coming headlamp. If someone, with a better knowledge of SF lights, can confirm that any other lights (as listen in SF comparison chart) has a tail switch that breaks the circuit, I will add them.

 

[Mikellen]

I was told by Henry from RA Lights that the RA Twisty has a parasitic drain. Does anyone know how much? According to HKJ, the Clicky has a 5 uA drain.

Thank you.

 

[recDNA]

I have been busy writing an article about what flashlight has standby drain, at the current time it is only in danish, but I will probably translate it to English when it is finished.
If anybody want a preview, it can be read here. I have calculated the expected lifetime of batteries with the actual standby drain, but ignoring any self discharge of the batteries.

I have a TK40 that I can't lock out because when I unscrew the cap or tail it has to get to the point of falling off before the clicky doesn't turn on the light. I know you said in your article the TK40 will drain AA's in 1.1 years but how long before it loses turbo function? In other words...if I leave batteries in it how long before I should replace them?

 

[HKJ]

I have a TK40 that I can't lock out because when I unscrew the cap or tail it has to get to the point of falling off before the clicky doesn't turn on the light. I know you said in your article the TK40 will drain AA's in 1.1 years but how long before it loses turbo function? In other words...if I leave batteries in it how long before I should replace them?

Fenix recommend unscrewing the head, but try checking the connection between the battery holder and the head, you might be able to bend the blades a bit, making it easier to do a lockout.

My drain rate is calculated from the specified battery capacity and does not include any self discharge of the batteries. I would recommend recharging at least every 6 month with eneloop, to keep some power on the light.

 

[recDNA]

Fenix recommend unscrewing the head, but try checking the connection between the battery holder and the head, you might be able to bend the blades a bit, making it easier to do a lockout.

My drain rate is calculated from the specified battery capacity and does not include any self discharge of the batteries. I would recommend recharging at least every 6 month with eneloop, to keep some power on the light.

Thanks.