Recurring Eneloop probs

[paulr]

I've experienced a problem several times since I've started using eneloops, that I'm not sure quite how to characterize (I have no measurements or anything like that). The basic behavior is the cells work fine when fully charged, but appear to poop out fairly early in the discharge cycle, especially at high currents. For example they stop being able to charge up the flash in my digicam after a fairly low number of shots. However, open circuit voltage measurements indicate that the cells are near-full as expected, and discharge on my BC-900 (usually at 250 mA) indicates plenty of remaining charge as well. It's as if the partially discharged cells sag severely under load partway through the cycle. A bit weirdly, I get the impression that this behavior stops further in the cycle when the cells are more discharged, i.e. it happens the most at maybe 75% charge. It occurs to me that this is also around the point where negative delta v happens during a charge cycle. I wonder if there's a local rise in internal impedance just around that point.

Any idea what might be going on? I'm reconsidering my plan of replacing all my various NiMH AA's with Eneloops because of this.

 

[TorchBoy]

This is with AA cells only? Have you done any discharge testing at higher currents?

 

[LuxLuthor]

Paul, I have not found a similar problem when using them with incand maglites. I have 24 cells, and have used 20 of them. Are you finding it with multiple sets, or just one set?

I also wonder what would happen if you did a couple of discharge/charge cycles even though supposedly they don't need it.

 

[MrAl]

Hi there,

I had this problem with the old Rayovac Renewal cells, but that was a different technology.

Are you using a charger that charges each cell individually? If not, one cell might
be halting the charge process too soon for the other cell to get fully charged.
This is why i went to a charger that does each cell individually, not in pairs.

 

[paulr]

I've noticed this with 2 sets of Eneloops. Just AA's, I think. I'm only using one Eneloop AAA right now, in a L0D CE, and haven't noticed this problem though it might be occurring. I'm usually charging in a BC-900, occasionally with an Energizer 15 minute charger. Both these chargers have 4 independent channels.

 

[carbine15]

Ive got 8 running a 6 cell magstar bulb and have no complaints. Only on the first cycle though.

 

[thekobk]

Were did you buy the batterys? most of us have had nothing but good things to say about the eneloops. Could the batterys be fakes?

 

[viorel00]

try to discharge them on the BC-900 using a high current (500 mA, I am not sure if you can discharge at higher current, I don't think so) and watch the voltage closely (yeap, very boring!) to see if there is a drop in voltage around 75% or so.

Even better, if you can set up the camera (either stand alone to connected to computer) to take shots every 30 seconds or so, the use the camera to take picture of the BC-900's display as you discharge the batteries, then watch the "movie" later at your convenience.

 

[paulr]

When charging there is -supposed- to be a drop (-dV) at 75% or so: should I be concerned the charger or cells might be missing it? I did charge up a set with an Energizer 15 minute chargeronce and they didn't get excessively hot or anything like that, and the charge ran about as long as expected.

I bought the cells at Wolf Camera.

 

[SilverFox]

Hello Paulr,

A point of clairification... The -dV occurs after full charge.

I have seen this this type of behavior with damaged cells. Looking at a discharge graph, you will see two voltage plateaus. This can also be observed in packs when one cell is driven to a reverse charge state.

There are two electrode's in a cell. They are at different voltage potentials, and one is larger than the other. Normal use only usually involves one of them, but if the discharge continues beyond its capacity, the voltage drops and the other electrode is discharged. This transition, in a healthy cell, occurs below the 0.9 volt cut off that is usually considered a fully discharged cell.

A faulty or damaged cell and upset this balance and exhibit dual voltage plateaus during discharge.

My best guess is that there is something strange going on...

Mark the cell and use it in single cell applications. It should get worse with use.

Tom

 

[paulr]

This is happening with more than one cell. I don't know how to diagnose which cells might be affected, if it's not all of them.

 

[paulr]

I begin to think something has gone wrong with my camera. It will only take about one flash shot with nimh batteries even if they're basically fully charged (though not hot off the charger). I tried this with two sets of eneloops and one set of Sanyo 2500's (that weren't self-discharged). I'm now putting all those cells through a discharge/charge cycle on my bc900 and will try with the hot-off-charger cells in the morning. I currently have a pair of L91 lithium primaries in the camera and those are working fine, fast flash cycling etc. So I think the camera has gotten less tolerant to slightly low battery voltage. It was not always like this. I used to take lots of flash shots. In fact not that long ago I took about 40 flash shots in a few minutes so maybe I fried something, though I don't remember the camera getting warm (Canon A530). I got the camera last year but I -think- it's still in warranty, so I may send it in for inspection.

 

[Hans]

I begin to think something has gone wrong with my camera. It will only take about one flash shot with nimh batteries even if they're basically fully charged (though not hot off the charger).

I had a similar problem with one of my large flashguns for my Nikon SLRs a few years ago. After a couple of shots the flashgun seemed to decide the voltage was too low, so it just stopped working. In that case I noticed very quickly it was the flashgun because I've got two identical flashguns, and the NiMH batteries that didn't fire the defective unit anymore one still worked fine in the other flashgun.

Hans

 

[PhotoWiz]

Well, this probably doesn't apply, but no one has mentioned sync voltage and camera sensitivity, so I'll throw that out.

Every flash has a voltage that it puts across the contacts (or sync cord) that goes to the camera. In newer flashes, that voltage is almost always quite low. But if you have a flash that's been hanging around for years, that voltage could be several hundred volts. If you sync one of these old flashes with your camera, it's possible to fry something internal to the camera. I have an old Nikon film camera that can only stand about 8 volts and an old Vivitar flash that puts out somewhere in the range of 280 volts. Needless to say, combining those two items together would be a very bad idea! Different cameras (including digital) have different sensitivities to high voltage.

I've never damaged a camera, but from what I understand this does not cause an instant failure in most cases. Instead I suspect your camera might start to behave erratically for a long time before it fails.

Of course, if you are using a dedicated flash that is made for the camera, this shouldn't be a problem. None of this would harm the flash by the way, only the camera you connect it to. So, you should always be able to use the flash test button and get correct functioning of the flash.

Also, firing a flash too many times over too short a time period can overheat the flash and that could create erratic behavior in the flash.

Just make sure you have ruled out all these things as contributing causes when you are trying to evaluate what is happening with your camera/flash/batteries.
Bill

 

[SilverFox]

Hello Paulr,

Have you checked your camera battery compartment lid against the recall notice for those cameras?

I believe some of the battery lids could short, or soft short out the batteries. If I remember correctly, there is a piece of wire that can bridge between the two contacts. Cannon should have information on this.

Tom

 

[wptski]

Well, this probably doesn't apply, but no one has mentioned sync voltage and camera sensitivity, so I'll throw that out.

Every flash has a voltage that it puts across the contacts (or sync cord) that goes to the camera. In newer flashes, that voltage is almost always quite low. But if you have a flash that's been hanging around for years, that voltage could be several hundred volts. If you sync one of these old flashes with your camera, it's possible to fry something internal to the camera. I have an old Nikon film camera that can only stand about 8 volts and an old Vivitar flash that puts out somewhere in the range of 280 volts. Needless to say, combining those two items together would be a very bad idea! Different cameras (including digital) have different sensitivities to high voltage.

I've never damaged a camera, but from what I understand this does not cause an instant failure in most cases. Instead I suspect your camera might start to behave erratically for a long time before it fails.

Of course, if you are using a dedicated flash that is made for the camera, this shouldn't be a problem. None of this would harm the flash by the way, only the camera you connect it to. So, you should always be able to use the flash test button and get correct functioning of the flash.

Also, firing a flash too many times over too short a time period can overheat the flash and that could create erratic behavior in the flash.

Just make sure you have ruled out all these things as contributing causes when you are trying to evaluate what is happening with your camera/flash/batteries.
Bill

I think that was the old Vivitar 283 but not the newer 285.

 

[petersmith6]

the newer 285!!lol.if you want a 285 to cycle quikely...get some Nicd's.the 285 has a thyristor in it to hold the charge to fire the flash.firing it to fast wont damage it.the 285 was avalable with a lead acid external power pack to allow profetionals to take pictures in rapid sucsetion.mine you that was 20 years ago.didnt know they still made them

 

[PhotoWiz]

Bill,

I have two, identical Vivitar 283s. On one the sync voltage is about 280 volts. On the newer one it is less than 12 volts. But they are both 283s. There may be a serial number difference, but you would be hard pressed to tell them apart!

I don't think any of the current flashes are in the 200+ volts range, but I do think there are some cameras that are very sensitive and some flashes that are above that sensitivity level.

Bill

 

[kurni]

I'm actually experiencing the opposite; my Canon PowerShot S3 IS keeps flashing beyond my expectation. I don't know how Eneloops perform with Speedlites tho.

 

[viorel00]

I'm actually experiencing the opposite; my Canon PowerShot S3 IS keeps flashing beyond my expectation. I don't know how Eneloops perform with Speedlites tho.

Same here. I took a brand new set of 4 AA Eneloops, discharged them in BC-900 and charged them back up, then put them in my Pentax dSLR *istD a few weeks before Thanksgiving and they're still going strong as of today, probably 600 shots so far. Not bad at all.