HIGH internal resistance eneloops

[adrianmariano]

I've had a few eneloops report HIGH resistance on my C9000 charger. I've had them for several years, but I don't think I've put them through very many cycles. I did have some batteries that were stored in a "Titanium" branded charger. Is it possible it killed them? I had another battery that sat in a Zebralight (unused) for several years. I'm pretty sure it was OK when it went in, but I get the HIGH error now. Can a battery get damaged just sitting in a light? Is there any way to "fix" these batteries?

 

[Lynx_Arc]

Yes batteries can be damaged by sitting in some devices if they have parasitic drain to them. I would NOT store batteries in any charger long term. It is fine to leave them there for awhile after you charge them but storing them is not recommended. There are some lights and devices that are poorly designed and can drain batteries in a few months.. dead. A decent light should not drain a battery on standby faster than about 5-7 years. multiple batteries in series can be drained such that one goes dead and the other reverse charges it some and this can damage batteries big time. In situations where this type of thing can happen you have to take steps to eliminate any chance of over discharging them in the device they are in.

 

[adrianmariano]

The battery could have been in the zebralight for 5 years. (I thought zebralight was decent!) But is drained the same thing as having high resistance?

 

[xxo]

The battery could have been in the zebralight for 5 years. (I thought zebralight was decent!) But is drained the same thing as having high resistance?

I some ways, yes. Internal resistance is not fixed, it generally gets higher the lower the state of charge - you might be able to get them to charge on your charger by first charging part way on a dumb charger or any charger that doesn't reject them. This will decrease the IR, maybe to the point that it will charge next time if you don't run it all the way down. Chances are though, being over discharged for years, that the cells are pretty badly damaged.

 

[Lynx_Arc]

The battery could have been in the zebralight for 5 years. (I thought zebralight was decent!) But is drained the same thing as having high resistance?

Not necessarily. It is possible you left the battery in the light discharged some and the parasitic drain of the light drained it the rest of the way. The only way to tell for sure is to either look up and see if someone checked the lights drain or check it yourself with a meter. Typically when a battery gets high IR it causes it to self discharge a lot faster but often by it being discharged too deeply it could be damaged by and the IR could be higher as a result.

 

[adrianmariano]

Not necessarily. It is possible you left the battery in the light discharged some and the parasitic drain of the light drained it the rest of the way. The only way to tell for sure is to either look up and see if someone checked the lights drain or check it yourself with a meter. Typically when a battery gets high IR it causes it to self discharge a lot faster but often by it being discharged too deeply it could be damaged by and the IR could be higher as a result.

Is there a way to check this with a regular multi-meter? I was actually thinking of trying to run a flashlight from a power supply and wondering what current it requires when it's turned on, but it's not obvious how to measure things since the light is closed up when operating. (The power supply that comes with the replacement battery kit is 1A, but it seems hard to find supplies with higher current.)

Neither of my two chargers seem to be dumb enough to try to charge the bad batteries. I saw a suggestion to take overly drained batteries and short them together with fully charged good batteries to try to partly charge them up. Is that a reasonable thing to do? Or should I just give up on my "HIGH" batteries? (I don't want to kill more batteries trying to fix the bad ones.)

 

[louie]

I am no expert on the phenomenon by any means, but have another data point.

I have a group of Eneloop AAA used constantly in my bike flashers. After maybe 10 years, some started to read HIGH in my C9000, yet the cells definitely had decent power and worked. I put these cells into a light and drained them for a while, then found the C9000 would charge them. This got tiresome, but I also wanted to try a new charger (an Xtar); I found that it happily charged these cells, and even do capacity tests. However, I thought it best to just replace the cells.

I've never had an AA Eneloop have this problem.

 

[Lynx_Arc]

Is there a way to check this with a regular multi-meter? I was actually thinking of trying to run a flashlight from a power supply and wondering what current it requires when it's turned on, but it's not obvious how to measure things since the light is closed up when operating. (The power supply that comes with the replacement battery kit is 1A, but it seems hard to find supplies with higher current.)

Neither of my two chargers seem to be dumb enough to try to charge the bad batteries. I saw a suggestion to take overly drained batteries and short them together with fully charged good batteries to try to partly charge them up. Is that a reasonable thing to do? Or should I just give up on my "HIGH" batteries? (I don't want to kill more batteries trying to fix the bad ones.)

If you have a digital meter with a low dc ma scale you can check it I think the light has a tailcap to it of some sort you take off the tail cap and put the meter on the lowest ma scale and touch one terminal to the battery, the other to the tube of the light that isn't anodized and you should see a reading on the meter. You can take the total mah of the battery in the light and divide it by that amount on the meter and that gives you the number of hours it should take to drain the light. You will have to first divide by 24 to get days then 365 for years. If the years are less than 1-2 you've got a light that you can't store a battery in at all. If it is 5-7+ years then you should check the light every year or so. Lights that drain batteries too quickly either need to be locked out (circuit broken) or batteries removed.
If a light can drain itself in less than a year then if it were mine I would replace it as it will sooner or later ruin batteries if you don't use it once a week then it may be sooner or later you don't use it once a year even.

 

[Lynx_Arc]

I am no expert on the phenomenon by any means, but have another data point.

I have a group of Eneloop AAA used constantly in my bike flashers. After maybe 10 years, some started to read HIGH in my C9000, yet the cells definitely had decent power and worked. I put these cells into a light and drained them for a while, then found the C9000 would charge them. This got tiresome, but I also wanted to try a new charger (an Xtar); I found that it happily charged these cells, and even do capacity tests. However, I thought it best to just replace the cells.

I've never had an AA Eneloop have this problem.

I'm not familiar with the C9000, someone with the charger may chime in about it. I have several chargers I use for nimh 3 of them. I use one old fast rayovac 1 hr charger to charge low voltage nimh cells that chargers reject, a second one to charge healthy cells that is gentle on them (Duracell mobile charger) and my analyzing and refreshing charger (BC900). My Duracell won't charge some cells that are old and not healthy and won't charge when the voltage is too low also. The BC900 will charge any battery as long as the voltage is high enough to detect. The Rayovac won't charge damaged cells properly but the pulsing of it checking the battery raises the voltage high enough to be detected by the other 2 chargers. I have a single cell BTC100 charger I've not used for nimh (bought it for lithium ion cells).
My BC900 charger is a good charger but people have had serious issues with it frying cells and catching fire etc which pretty much killed it as a contender for charging. If I were to try a new charger I would probably get a BTC3100 or 3400 charger so I can charge 4 cells at once.

 

[louie]

For reference, the C9000 would be the popular Maha-Powerex MH-C9000 WizardOne 4-slot NiMH charger.

 

[adrianmariano]

If you have a digital meter with a low dc ma scale you can check it I think the light has a tailcap to it of some sort you take off the tail cap and put the meter on the lowest ma scale and touch one terminal to the battery, the other to the tube of the light that isn't anodized and you should see a reading on the meter. You can take the total mah of the battery in the light and divide it by that amount on the meter and that gives you the number of hours it should take to drain the light. You will have to first divide by 24 to get days then 365 for years. If the years are less than 1-2 you've got a light that you can't store a battery in at all. If it is 5-7+ years then you should check the light every year or so. Lights that drain batteries too quickly either need to be locked out (circuit broken) or batteries removed.
If a light can drain itself in less than a year then if it were mine I would replace it as it will sooner or later ruin batteries if you don't use it once a week then it may be sooner or later you don't use it once a year even.

I tried to measure current of my light in operation (not parasitic) as follows: I connected one lead to the spring in the tailcap and pressed the other lead against the back of the battery in the light. Then I tried to turn the light on...but nothing happened. No light. No current reading. What am I doing wrong here?

 

[louie]

You haven't completed the circuit. The body of the light to the sides of the tailcap is the other conductor.

Even then, it's not clear where you have your ammeter connected.

 

[Lynx_Arc]

I tried to measure current of my light in operation (not parasitic) as follows: I connected one lead to the spring in the tailcap and pressed the other lead against the back of the battery in the light. Then I tried to turn the light on...but nothing happened. No light. No current reading. What am I doing wrong here?

If the tailcap is removeable set it aside. With the battery in the light touch one lead to the battery center and the other to the body of the light where the tailcap screws on. Set the meter to ma scale and if required you may have to change the lead sockets of the + lead on some meters. If it has an electronic switch you should measure some ver low current numbers likely a fraction of a ma, the lower the better.

DO NOT TURN THE LIGHT ON as it is likely more than a low amp scale can handle you may damage your meter.

 

[adrianmariano]

If the tailcap is removeable set it aside. With the battery in the light touch one lead to the battery center and the other to the body of the light where the tailcap screws on. Set the meter to ma scale and if required you may have to change the lead sockets of the + lead on some meters. If it has an electronic switch you should measure some ver low current numbers likely a fraction of a ma, the lower the better.

DO NOT TURN THE LIGHT ON as it is likely more than a low amp scale can handle you may damage your meter.

Note that my meter is autoranging and has two current scales. For this particular test I had the meter on the amp scale. My intention was to determine whether a 1A power supply can run this light or not. The tailcap has the light's power switch, so it's not clear that I can omit the tailcap from the measurement. As noted, I pressed the power switch. The light didn't turn on, though. I tried the same test with a second light that also had a switch in the tail with the same result. Hmmm. I need a wire connecting the tailcap to the main body, don't I?

 

[Lynx_Arc]

Note that my meter is autoranging and has two current scales. For this particular test I had the meter on the amp scale. My intention was to determine whether a 1A power supply can run this light or not. The tailcap has the light's power switch, so it's not clear that I can omit the tailcap from the measurement. As noted, I pressed the power switch. The light didn't turn on, though. I tried the same test with a second light that also had a switch in the tail with the same result. Hmmm. I need a wire connecting the tailcap to the main body, don't I?

If you are not powering it with a battery you will need to run a wire down inside to the contact on the circuit board as you have to mimic the battery connections with an external Power supply You shouldn't need the tail cap just touch one lead to the body the other to the center pin/spring on the circuit board inside hopefully without shorting things out.

 

[adrianmariano]

If you are not powering it with a battery you will need to run a wire down inside to the contact on the circuit board as you have to mimic the battery connections with an external Power supply You shouldn't need the tail cap just touch one lead to the body the other to the center pin/spring on the circuit board inside hopefully without shorting things out.

I was measuring with batteries installed. But to close the circuit I need the tailcap to touch the body. Note also that this light uses tailcap touches to change brightness. I guess I don't know if brief power interruptions are all that's needed to signal the electronics to switch modes. I suppose I can try testing with the tailcap out of the circuit and see if the light comes on.

For using a power supply I was planning to go the easy route and use a dummy battery, otherwise it seems hard to get a decent connection deep inside the light. With a dummy battery the only challenge is cutting a slot for the wires that doesn't prevent me from screwing the tailcap back on. Well, that and confirming that the power supply can provide sufficient current. Based on the specs the 1A supply should be OK as long as I avoid Turbo mode, which is supposed to last only 1.5 hours. High is supposed to last 4.5 hrs, which would be 0.9 A, so getting kinda close to 1A.

Here's an example of the dummy battery setup with included 1A supply:
https://www.amazon.com/gp/product/B082W3TFH5/?tag=cpf0b6-20

I was looking around a bit for a higher current supply, but hard to find anything really substantially higher. I might want to run two lights on one supply eventually.

 

[Lynx_Arc]

I was measuring with batteries installed. But to close the circuit I need the tailcap to touch the body. Note also that this light uses tailcap touches to change brightness. I guess I don't know if brief power interruptions are all that's needed to signal the electronics to switch modes. I suppose I can try testing with the tailcap out of the circuit and see if the light comes on.

For using a power supply I was planning to go the easy route and use a dummy battery, otherwise it seems hard to get a decent connection deep inside the light. With a dummy battery the only challenge is cutting a slot for the wires that doesn't prevent me from screwing the tailcap back on. Well, that and confirming that the power supply can provide sufficient current. Based on the specs the 1A supply should be OK as long as I avoid Turbo mode, which is supposed to last only 1.5 hours. High is supposed to last 4.5 hrs, which would be 0.9 A, so getting kinda close to 1A.

Here's an example of the dummy battery setup with included 1A supply:
https://www.amazon.com/gp/product/B082W3TFH5/?tag=cpf0b6-20

I was looking around a bit for a higher current supply, but hard to find anything really substantially higher. I might want to run two lights on one supply eventually.

Running lights off power supplies could have issues on the highest modes from heat buildup. I'm not sure if removing the battery helps or harms heat dissipation or not but likely if you avoid running on Turbo should be fine. Not sure why you see a need to run lights off a Power Supply though. As for power supplies you could get a buck circuit and a 5v or 12v high current supply and step down the voltage to whatever you desire

 

[ChrisGarrett]

First question is, is are they Eneloop Pros, which are their High-Cap offerings?

If so, a couple/few years out of them is totally expected before high I.R.s kill them.

Chris

 

[adrianmariano]

First question is, is are they Eneloop Pros, which are their High-Cap offerings?

If so, a couple/few years out of them is totally expected before high I.R.s kill them.

Chris

No, regular eneloops, not Pro.

 

[adrianmariano]

Running lights off power supplies could have issues on the highest modes from heat buildup. I'm not sure if removing the battery helps or harms heat dissipation or not but likely if you avoid running on Turbo should be fine. Not sure why you see a need to run lights off a Power Supply though. As for power supplies you could get a buck circuit and a 5v or 12v high current supply and step down the voltage to whatever you desire

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.)