HIGH internal resistance eneloops

[Lynx_Arc]

I've been using the light as a task light. I have it mounted on loc-line so I can position it. And it's constantly running down and I have to change the batteries.

Can I buy a "buck circuit" device that's easy to connect to my power supply? Does it keep max current constant as it drops the voltage? People talk about dropping the voltage with a resistor, but that means more heat (and wasted power). I haven't seen anybody suggest a more sophisticated approach...unless it's adding a capacitor to smooth out power variations.

Why would heat dissipation be different when running off a power supply? (Presumably the main concern would be if I tried to run it in Turbo for a long time and it was really not designed for continuous operation in Turbo.)

yes a buck circuit swaps current for voltage that is it takes less current to operate the higher the input voltage and when the input drops too low likely it will cut out.
As for heat dissipation you aren't using a battery which may help absorb some of the heat and if the light isn't a headlamp then your hand is also used to absorb heat from the light too and if the battery can only run for a short time on batteries instead of days on end using a power supply the chance increases that the heat has longer to build up.

 

[adrianmariano]

yes a buck circuit swaps current for voltage that is it takes less current to operate the higher the input voltage and when the input drops too low likely it will cut out.
As for heat dissipation you aren't using a battery which may help absorb some of the heat and if the light isn't a headlamp then your hand is also used to absorb heat from the light too and if the battery can only run for a short time on batteries instead of days on end using a power supply the chance increases that the heat has longer to build up.

So can I buy a buck circuit convertor or is it something that would be a component to solder onto a board? A reason I asked the question is that I found in my searches an adjustable voltage power supply, but it's advertised as being 3A at every voltage, so evidently when you lower the voltage the current does not go up---you just get less power. Seems odd that it wouldn't be a constant power supply.

I didn't think of the possibly of the hand being part of the heat sink. Most of the situations where I'd run a light for a long time would be like tailstanding on a table, say, not in my hand.

I tried skipping the tailcap and was able to measure the current at 325 mA in the brighter mode (which I believe is the non-turbo mode). This suggests that even the 1A supply might suffice to drive two of these lights.

However, I could not measure the parasitic current because I couldn't have the light turned off with my leads connected. I tried a Fenix and got 180 mA when on but couldn't measure it off for the same reason.

I tried a parasitic measurement on a zebralight and my meter just reports zero. This one has the switch in the side of the body, so I can turn it off while measuring.

 

[Lynx_Arc]

My Fluke has an Amp scale and a ma scale, if you set it to measure amps then fractions of ma likely won't register you have to change to that setting. Parasitic drain is always there when the battery is inserted regardless of turning off. The light would have to be locked out to stop the small drain. It basically is a tiny amount of power that queries the push button switch to see if you have pressed it or not without it digital switches would not work, you would need a mechanical switch likely a reverse clicky and I don't think Zebralights have clicky switches.
Likely the current should be in the tens of microamps range that would mean 5+ years to drain the battery when not used and not locked out.

As for power supplies most today using wall power are switching supplies not buck circuits as the input is AC and buck circuits are designed for DC input and convert it to a rough form of AC then run it through an inductor and essentially transforms it into lower voltage with higher current as power stays the same with some loss in conversion. The advantage of buck conversion is unlike using a linear regulator or resistor you aren't burning off excess voltage as heat so a lot less power loss and a lot less heat in some cases.
I seriously doubt the Zebralight has parasitic drain issues but it isn't out of the question as I think I have heard of someone that had to sned one back because it drained the battery in less than a month or something like that. I've had other devices that developed unusable parasitic drain mostly remote control stuff. I bought some LED puck lights that are wireless radio controlled and they worked fine but 2 days later the light was completely dead from parasitic drain. I also had some 3AAA incan tap lights that had a digital pushbutton switch on them that after 3 weeks were dead. The parasitic drain was 4ma so each day 100ma of the 1600mah batteries vanished. I ended up removing the switches and throwing them in the parts bin and replacing with mechanical switches.

 

[adrianmariano]

My Fluke has an Amp scale and a ma scale, if you set it to measure amps then fractions of ma likely won't register you have to change to that setting. Parasitic drain is always there when the battery is inserted regardless of turning off. The light would have to be locked out to stop the small drain. It basically is a tiny amount of power that queries the push button switch to see if you have pressed it or not without it digital switches would not work, you would need a mechanical switch likely a reverse clicky and I don't think Zebralights have clicky switches.
Likely the current should be in the tens of microamps range that would mean 5+ years to drain the battery when not used and not locked out.

As for power supplies most today using wall power are switching supplies not buck circuits as the input is AC and buck circuits are designed for DC input and convert it to a rough form of AC then run it through an inductor and essentially transforms it into lower voltage with higher current as power stays the same with some loss in conversion. The advantage of buck conversion is unlike using a linear regulator or resistor you aren't burning off excess voltage as heat so a lot less power loss and a lot less heat in some cases.
I seriously doubt the Zebralight has parasitic drain issues but it isn't out of the question as I think I have heard of someone that had to sned one back because it drained the battery in less than a month or something like that. I've had other devices that developed unusable parasitic drain mostly remote control stuff. I bought some LED puck lights that are wireless radio controlled and they worked fine but 2 days later the light was completely dead from parasitic drain. I also had some 3AAA incan tap lights that had a digital pushbutton switch on them that after 3 weeks were dead. The parasitic drain was 4ma so each day 100ma of the 1600mah batteries vanished. I ended up removing the switches and throwing them in the parts bin and replacing with mechanical switches.

I keep wondering if I should upgrade my multimeter. When I attempted to measure parasitic current I selected the mA scale and because the autoranging seems slow and flaky I selected the smallest scale, which showed 0.00 mA. It matters that the light is off because when it's on I get 325 mA---I just see the current to power the LED, not the parasitic current. The zebralight is not clicky. But if the parasitic current is 0.01 mA I can imagine my meter being unable to measure it. (Maybe I should upgrade my meter...but I probably do not want to spend what I'd need to get a meter that measures microamps.)

It would have been interesting if I could have measured parasitic drain on the Nitecore EA4W Pioneer, which runs a blue light around the power switch while it's off, and like I said, kills it's 4 AA batteries in a few weeks. I think I should be measurable by my meter, if I had a way to set up the measurement.

 

[Lynx_Arc]

I keep wondering if I should upgrade my multimeter. When I attempted to measure parasitic current I selected the mA scale and because the autoranging seems slow and flaky I selected the smallest scale, which showed 0.00 mA. It matters that the light is off because when it's on I get 325 mA---I just see the current to power the LED, not the parasitic current. The zebralight is not clicky. But if the parasitic current is 0.01 mA I can imagine my meter being unable to measure it. (Maybe I should upgrade my meter...but I probably do not want to spend what I'd need to get a meter that measures microamps.)

It would have been interesting if I could have measured parasitic drain on the Nitecore EA4W Pioneer, which runs a blue light around the power switch while it's off, and like I said, kills it's 4 AA batteries in a few weeks. I think I should be measurable by my meter, if I had a way to set up the measurement.

You would be surprised at how little current it takes to light up an LED. I have some USB dimmable LED modules and most power banks won't keep them on when they are dimmed all the way down and when I got a power bank that would stay on my USB meter couldn't measure the amount I bought a better USB meter and it was a fraction of a ma of current used I don't quite remember exactly but I can run 4 USB LED modules off 2 18650s in a power bank for 8-12 hours a day for 2-3 weeks without recharging. It is when you start approaching a ma things go bad as 24 hours a day is 24ma and not quite 200ma/week or about 700ma a month so in 3 months a 2000ma 18650 is dea and if you are using less powerful it goes faster or if you use the light and don't recharge it you may only have a half a charge to drain.
If you don't have it on the lowest scale then the accuracy at small currents usually is limited. If you have 0.005ma then it may measure 0.01ma or not may go back and forth as it rounds up/down.
I would consult the manual for your meter to see what it can measure it should tell you and tell you how to measure various things.
If a light is killing batteries in a few weeks likely it is in the 5-10ma range of drain.
I just read a CPF thread equating it would drain batteries in about 2 weeks if you don't lock it out. There is a lock out mode you need to put it in that reduces battery drain they say.

 

[adrianmariano]

You would be surprised at how little current it takes to light up an LED. I have some USB dimmable LED modules and most power banks won't keep them on when they are dimmed all the way down and when I got a power bank that would stay on my USB meter couldn't measure the amount I bought a better USB meter and it was a fraction of a ma of current used I don't quite remember exactly but I can run 4 USB LED modules off 2 18650s in a power bank for 8-12 hours a day for 2-3 weeks without recharging. It is when you start approaching a ma things go bad as 24 hours a day is 24ma and not quite 200ma/week or about 700ma a month so in 3 months a 2000ma 18650 is dea and if you are using less powerful it goes faster or if you use the light and don't recharge it you may only have a half a charge to drain.
If you don't have it on the lowest scale then the accuracy at small currents usually is limited. If you have 0.005ma then it may measure 0.01ma or not may go back and forth as it rounds up/down.
I would consult the manual for your meter to see what it can measure it should tell you and tell you how to measure various things.
If a light is killing batteries in a few weeks likely it is in the 5-10ma range of drain.
I just read a CPF thread equating it would drain batteries in about 2 weeks if you don't lock it out. There is a lock out mode you need to put it in that reduces battery drain they say.

I don't think my meter came with instructions. If it did, they were along the lines of "Insert batteries in the correct direction and don't operate under water". It's an unbranded model. It may show a scale going down to 0.00 mA but really only reliably measure signals that are significantly above 0.01 mA.

When looking through my instruction sheets to see if I had one for the multimeter I found the instructions for the EA4W which explains how to enter "lockout" mode, which is good to know.

What's the verdict on the high resistance batteries? Just toss them? What about shorting to another battery to try to get some charge in there?

 

[Lynx_Arc]

I don't think my meter came with instructions. If it did, they were along the lines of "Insert batteries in the correct direction and don't operate under water". It's an unbranded model. It may show a scale going down to 0.00 mA but really only reliably measure signals that are significantly above 0.01 mA.

When looking through my instruction sheets to see if I had one for the multimeter I found the instructions for the EA4W which explains how to enter "lockout" mode, which is good to know.

What's the verdict on the high resistance batteries? Just toss them? What about shorting to another battery to try to get some charge in there?

Easiest thing to do is get a couple of wires or paper clips and a charged battery and connecting them together for about 5-10 seconds and try to see if the charger can "see" it then. Sometimes if you catch the battery early after it has been discharged too much the damage is less disasterous but often when they are discharged below about 0.5v there is loss of capacity and even develop high internal resistance shows up. When a battery is discharged too low to be detected by a charger it may be time to run it through a refresh cycle and check the capacity as if it loses enough capacity it will be a lot more easy to damage further in series in a device that doesn't shut off when voltage drops too low. When I have a nimh battery that is less than 80% of listed capacity and don't have others of similar health I relegate it to use in non critical use such that I don't need to depend on it to perform and if it gets further damage it is no loss. When a battery drops to 50% of capacity then it is junk. I've got to the point when a battery drops below about 2/3 capacity I mark red lines on it to signify it is a fragile (bad) cell in use. When I have more than enough cells to go around the bad cells get tossed. I just tossed a pair of AAA nimh Rayovac hybrids that after a refresh cycle only measured about 50mah each. The chinese based LSD nimh from back then have shown to be rather fragile as about half of them I've tossed due to substantial losses of capacity and some develop HSD (high self discharge) that renders them useless for all but immediate use after charging. I did at one time keep some HSD Energizer 2500s that did have nearly full capacity for a 1AA LED headlamp that I used heavily at one time. I would keep 1-2 cells on a fast charger and swap them in/out of it all day as the runtime was about 1.5 to 2 hours a charge and I was using it constantly for 8-10 hours on a project and the higher capacity meant an extra 15-30+ minutes without having to stop and swap out the battery. Now I've gone to 18650 and I tossed those 2500s in the trash.

 

[snakebite]

http://aacycler.com/post/trickle-charging-lsd-cells/
its possible your "titanium"charger trickled them to death.
best to look at info HKJ posts on chargers.
lots of cheap chargers murder batteries.

 

[Lynx_Arc]

http://aacycler.com/post/trickle-charging-lsd-cells/
its possible your "titanium"charger trickled them to death.
best to look at info HKJ posts on chargers.
lots of cheap chargers murder batteries.

I agree, plus leaving batteries in chargers for weeks after they are "done" is IMO a no-no as who knows if he charger detection "pulse" to see if a cell is in the slot is not designed well and can also trickle charge batteries some too. i have an old Rayovac 1 hour charger that I use to "charge dead nimh to a high enough voltage that my other charger can "see" them. It blinks error but does charge it enough that my Lacrosse BC900 can then charge them as it will will charge batteries other chargers reject. I use it for my junk batteries and on occasion using the refresh mode it can restore batteries to normal enough that the other chargers accept them.

 

[adrianmariano]

It looks like four of the high resistance batteries got trashed. I had the one left that I pulled out of the zebralight. I measured it's no-load voltage and got something very low, like 0.15 V. I shorted it to a freshly charged eneloop. It was fairly slow to bring up the voltage---five to ten seconds wasn't even close to sufficient. Maybe it took about a minute to come up to 0.35 V. I tried sticking it in the C9000 at this point and the C9000 is willing to charge it. I'll run a refresh cycle and see what capacity it has.

 

[Lynx_Arc]

It looks like four of the high resistance batteries got trashed. I had the one left that I pulled out of the zebralight. I measured it's no-load voltage and got something very low, like 0.15 V. I shorted it to a freshly charged eneloop. It was fairly slow to bring up the voltage---five to ten seconds wasn't even close to sufficient. Maybe it took about a minute to come up to 0.35 V. I tried sticking it in the C9000 at this point and the C9000 is willing to charge it. I'll run a refresh cycle and see what capacity it has.

Yeah I guess it can take longer than that some of it depends on how deep the discharge below threshhold was.
Let me know how it goes. My "guess" would be about a 20-25% loss in capacity if the internal resistance goes back to near normal when refreshed but if it stays pretty high then likely half capacity or more lost.... I'm guessing however so don't take this as an "expert" on this subject as there are others who test these nimh batteries to death and have threads discussing them in great detail that if they chime in I would be glad to be pointed out at wrong if I am.

 

[adrianmariano]

Yeah I guess it can take longer than that some of it depends on how deep the discharge below threshhold was.
Let me know how it goes. My "guess" would be about a 20-25% loss in capacity if the internal resistance goes back to near normal when refreshed but if it stays pretty high then likely half capacity or more lost.... I'm guessing however so don't take this as an "expert" on this subject as there are others who test these nimh batteries to death and have threads discussing them in great detail that if they chime in I would be glad to be pointed out at wrong if I am.

When I checked the capacity listed was zero. And the voltage was still low. I tried shorting it with the good battery for longer and the voltage went up. And then I checked again...and now my charger is complaining about high resistance again. So it's not looking good.

I also noticed that my multimeter has a microamp setting. With this setting the Zebralight reports a 2.3 microamp parasitic drain. Though weirdly it sometimes gets stuck on a number around 1200 microamps. Not sure what's going on there. Meter flakiness?

 

[Lynx_Arc]

When I checked the capacity listed was zero. And the voltage was still low. I tried shorting it with the good battery for longer and the voltage went up. And then I checked again...and now my charger is complaining about high resistance again. So it's not looking good.

I also noticed that my multimeter has a microamp setting. With this setting the Zebralight reports a 2.3 microamp parasitic drain. Though weirdly it sometimes gets stuck on a number around 1200 microamps. Not sure what's going on there. Meter flakiness?

That is the problem with some chargers they won't charge cells that aren't healthy at all. 2.3uA is very low current probably 10 years to drain the battery in standby. I've had some lights that without an average current setting you can't get a good reading. From what I've read Zebralights unless they have a bad circuit have no problems with parasitic drain but I have heard on person that had to return a light due to it likely it was a rare occurrence. 1200uA is 1.2ma not sure but it could be the light tests the battery when it detects one in there perhaps.