[Slightly OT] Cutoff voltage of cameras favors Low Self-Discharge batteries?

[mishoo]

I should perhaps have posted this on dpreview, but their white-on-black color scheme hurts my eyes.

I've read this review of Sony Eneloops at Epinions, which says that, at least for Canon cameras, you get more practical short-term usage out of 2000mAh LSD batteries than out of 2500mAh regular ones:

Now, what about the fact that AA eneloops are rated at 2000mAh and most regular NiMH AA batteries are rated at 2500mAh and above? While waiting for my eneloops to arrive in the mail, I had bought a new set of Energizer 2500mAh batteries, charged them and tested them in my camera. I got 300 mostly flash pictures. So, despite the higher mAh rating, the Energizer batteries didn't run as long as the eneloops because their voltage dropped to the camera cutoff point sooner. Only if your device has a cutoff voltage of around 0.9 volts per cell would you benefit from higher capacity regular NiMH batteries

Can someone comment? Thanks.

 

[Mr Happy]

There are two facts I can give you:

1. Eneloops do maintain a higher voltage during discharge than many other NiMH cells,
2. Eneloops work nicely in my Canon camera.

I have never put anything other than Eneloops in my camera so I can't give you a comparison. The low self-discharge feature is what matters most to me.

 

[mdocod]

My Kodak 2xAA powered digicam is VERY picky about that low voltage cuttoff, I have tried tenergy 2600mAH, powerizer 2500mAH, Rayovac 1800mAH, Digital 2200mAH, Energizer 2500mAH, Nuon lithium primaries, and many brands of Alkaline, the eneloops have out-performed everything I have used in this camera by 2-6X the number of pictures. Before the energizers developed their major self-discharge problems (only took about 10 cycles), they were pretty close, but since they are junk within just a few cycles they really don't even compete, the Tenergy 2600mAH cells don't do too bad in most applications, my low drain lights (1 amp or less) perform perfectly well on them, and they will even power an ROP high reasonably bright. But there is something about the eneloops, that keeps the camera happy through most of the discharge.

Keep in mind when comparing cells, that there is a major difference between AH and WH, often times eneloops can deliver more WH for a similar AH.

In studying Silverfox's discharge charts, you will see something amazing when you compare eneloops to other more typical cells:

eneloop@2A discharge, 1.81AH, 2.16WH, do the math and you figure the cell averaged 1.19V through the discharge, pretty good..

Here's some other examples:
Titanium, @2A discharge 2.25H, 2.59, Meaning that it only averaged 1.15V through the discharge.
More examples @2A
Amsmann 2300mAH only averages 1.12V
Powerex 2300mAH only averages ~1.16V
AccuPower 2600s ~1.13V
Energizer 2100s ~1.13V
RayoVac 1800s ~1.13V




Anyways... the point being... lets say the camera draws 2 amps when charging the flash and running the LCD, (just guessing, I have no idea)... Then lets say the camera considered the batteries "dead" when the loaded voltage drops below ~1.15V(hypothetical), then most cells will cause the camera to think it's dead before the cell is half discharged. While eneloops will let you use maybe closer to 80-90% of actual capacity before the camera is fooled into thinking they are dead.

 

[coppertrail]

I've replaced all my standard NiMH AA cells with eneloop in my Canon AA DigiCams and have had great results. When I'm on vacation and taking a lot of shots, I load up the Powerex 2700 mAh cells, the best standard cells IMO.

 

[UnknownVT]

Most LSD batteries do seem to maintain a higher voltage than regular NiMH -
eneloop actually claims this on their Canadian site .

The Pentax K100D dSLR uses 4x AA, and is well known to be very battery fussy -
this Post #49 (link) in thread - K100D - "Low-Battery" Problem gives details of the cutoff voltage levels.

The poster said his Uniross Hybrios maintains higher voltage.

I use both Kodak Pre-Charged and eneloops as back up for the dSLR -
BUT charge up a set of 2500mAh regular NiMH (cheapo Digital Concepts/Sakar "generic" looking batteries from WalMart) on the day of the shoot (or night before) and get very good results - last long shoot I took 525 shots in one evening and the batteries only were depleted during an extended review at home - so they more than served their task - and well.

I keep the LSD in the camera (and a spare set in the bag) when not on a shoot so it is always ready for use.

see also this thread -

My Eneloops charge to and hold a higher voltage than other LSD's ...

 

[Mr Happy]

Apart from being made in China, the Uniross Hybrios look very similar to Eneloops. Possibly the same technology made under license?

I bought some Kodak Pre-Charged to test, but I found them to have a very low voltage. On a discharge test at 500 mA they started out at 1.16 V and decreased to 1.10 V towards the end of the run. This is a much lower voltage than Eneloops.

 

[UnknownVT]

I bought some Kodak Pre-Charged to test, but I found them to have a very low voltage. On a discharge test at 500 mA they started out at 1.16 V and decreased to 1.10 V towards the end of the run. This is a much lower voltage than Eneloops.

WoW! that is really low - so low that the Kodak Pre-Charged shouldn't even work in the Pentax K100D, if that Pentax K100D post measurements were correct - that poster claimed 1.19V (per battery) was the cutoff voltage.

I don't have means to take discharge readings -
but the open-circuit voltages (I realize are less meaningful) at about 3 months storage were the same for Kodak Pre-Charged and eneloops (measured for a set of 4 for each) - about 1.33V. I then also did "flash amps" (thanks to you they are now more realistic:thumbsup eneloops averaged 10A and Kodak Pre-Charged 9A - then o-c voltage readings after the flash amps were both about 1.32V.

However maybe I should switch to two sets of eneloops as back up for the Pentax K100D, and use Kodak Pre-Charged for other uses.
Thanks for the info.

Apart from being made in China, the Uniross Hybrios look very similar to Eneloops. Possibly the same technology made under license?

Of all the LSDs the Hybrios seem the be the most differently spec'd from eneloops -

eneloop - 2000mAh, 1,000 cycles
Uniross Hybrio - 2100mAh, 500 cycles

I always thought the Hybrios were the "typical other" (Yuasa made) LSDs -
but like I said, I do bow to your better knowledge in these battery matters.

 

[Mr Happy]

My test on the Kodak Pre-Charged was with the cells straight out of the package as purchased. All four cells measured 1.29 V open circuit before I started, but the voltage dropped down to 1.16 V almost immediately I began the discharge test. It's possible they are suffering voltage depression and they might improve if I do a break-in cycle on them.

The Kodak cells did have a respectable initial charge at 1700 mAh for each cell. But the mAh capacity doesn't tell the whole story, since if the voltage is lower devices will either run at lower power or will draw more current to compensate. It is the mWh measurement that really gives the best information about energy storage.

Regarding LSD designs, there do seem to be two basic types; those with white tops and a squarish button like Eneloops, and those with black tops and a rounder button like the Kodak cells. The Uniross Hybrios have the white top and squarish button. I don't know if that means anything beyond appearance. I might run a couple of Hybrios side-by-side with Eneloops on the C9000 to see if their electrical characteristics are similar.

The black top cells also have a slightly different shape on the negative end. I have not looked closely enough at various different brands to see if there is variation within these two categories.

As others have reported, the Kodak cells are significantly larger in diameter than many cells and will not fit in devices where clearance is tight. It would be interesting to know if other black top, made in China cells also have a larger diameter.

 

[UnknownVT]

Regarding LSD designs, there do seem to be two basic types; those with white tops and a squarish button like Eneloops, and those with black tops and a rounder button like the Kodak cells. The Uniross Hybrios have the white top and squarish button. I don't know if that means anything beyond appearance. I might run a couple of Hybrios side-by-side with Eneloops on the C9000 to see if their electrical characteristics are similar.
The black top cells also have a slightly different shape on the negative end. I have not looked closely enough at various different brands to see if there is variation within these two categories.
As others have reported, the Kodak cells are significantly larger in diameter than many cells and will not fit in devices where clearance is tight. It would be interesting to know if other black top, made in China cells also have a larger diameter.

I haven't read of any other LSD batteries being fatter other than the Kodak Pre-Charged.

There's a comparison photo that's been posted on CPF between the Kodak, eneloop and RoV Hybrid - in Post #9 - I know the photo came from some other post originally - that's why I haven't just linked it here as I would not be able to give proper credit.

Chevrofreak has a comparison photo of the -ve ends between the Kodak P-C and Hybrio in Post #10 of thread - new Kodac "Pre Charged" NiMH batteries? -
he also did some runtimes in a flashlight comparing the Kodak P-C and Hybrio - in posts #13 and #14

Anyway with my limited knowledge and experience I tend to feel that although there may be absolute measurable differences - eneloops and Kodak Pre-Charged behave for me in the overall scheme of things very similarly - of course taking these to extremes may show one is better than the other - but for my usage and variation/inconsistency - for all intents and purposes I feel they are kind of "the same". My apologies for this very non-objective view of things.

I can, and will, happily stand corrected

 

[Mr Happy]

Thanks for digging those pictures up, Vincent. One of those pictures certainly indicates there are at least three different kinds of cell where outward appearance is concerned.

Your comment about them being "the same" is quite valid. For most practical purposes I'm sure that's true.

When it comes down to details, we could say that Eneloops will run brighter in high power incandescents, while Kodaks will run a little longer in regulated LEDs. A note of caution is the Kodaks may not fit in some devices where the batteries are a tight fit.

 

[UnknownVT]

Your comment about them being "the same" is quite valid. For most practical purposes I'm sure that's true.
When it comes down to details, we could say that Eneloops will run brighter in high power incandescents, while Kodaks will run a little longer in regulated LEDs. A note of caution is the Kodaks may not fit in some devices where the batteries are a tight fit.

Even though in practice they're probably similar -
that doesn't prevent me from wanting to know which are better -
or even the "best" LSD.

My ad-hoc (read: unscientific) impression as of now -
eneloops are the most well known and popular - the benchmark that other LSDs are compared to
(also lots of reports suggesting that they are very well made batteries - I agree, but don't know how people can actually know that)
- so by default I regard them as the "best", until I read otherwise.

However almost all LSD batteries have had good reports -
so I can buy them by price with some confidence -
other than the CostCo eneloop pack ($26 for 8x AA, 4xAAA 4-position charger, and D&C adaptors) and the now all gone $15/8, then on closeout $13/8 at Circuit City, also HH Gregg seems to have them at good prices - eneloops are mostly "premium" priced.

Whereas Kodak Pre-Charged are $7.88/4 from any local WalMart -
this would seem bargain priced for LSDs -
especially considering Chevrofreak's positive report in
new Kodac "Pre Charged" NiMH batteries? - runtime tests in a flashlight comparing the Kodak P-C and Hybrio - in post #14

The measurements for Kodak Pre-Charged being fatter was in
Kodak vs Rayovac (Low self discharge) NiMH

Mr Al posted the measurements in Post #7
and a summary by LEDninja in post #12
"Standard alkaline
0.555 in. 14.097 mm Rayovac AA alkie
0.555 in. 14.097 mm Energizer "Industrial" AA alkie
NiMH
0.560 in. 14.2240 mm +0.005 in. +0.1270 mm RS 1800
0.562 in. 14.2748 mm +0.007 in. +0.1778 mm Empire 2000
0.562 in. 14.2748 mm +0.007 in. +0.1778 mm Energizer 2500
0.569 in. 14.4526 mm +0.014 in. +0..3556 mm Kodak PreCharged"

 

[Mr Happy]

On close examination of some Uniross Hybrios that I have, I have decided they are outwardly identical to Eneloops. The shape and appearance is identical, and on measuring with calipers the length and diameter are identical.

Hybrios are available in Fry's at $9.99/4.

I am currently doing some tests to see if their electrical properties are the same as Eneloops. Initial impressions suggest this to be likely, but I will report back later when I have completed my testing.

Note for reference that Eneloops are about 14.1 mm in diameter.

 

[UnknownVT]

On close examination of some Uniross Hybrios that I have, I have decided they are outwardly identical to Eneloops. The shape and appearance is identical, and on measuring with calipers the length and diameter are identical.
I am currently doing some tests to see if their electrical properties are the same as Eneloops. Initial impressions suggest this to be likely, but I will report back later when I have completed my testing.

Very cool - thank you very much - looking forward to reading your results.

If you wouldn't mind please also compare the Kodak Pre-Charged you have?