NiMH batteries ability to hold charge?

I've managed to accumulate more NiMH batteries than I'll ever need for my digital camera. 2 or 3 sets should be enough to rotate through my camera--especially considering my C-5050's excellent power management--but I have 5 or 6 sets (the reason for that is a long story). All of the sets have been used at least a couple of times.

So, my question is: If I don't use a set or two for a long time, can they completely lose their ability to hold a charge? I know that once you finish charging a set, it starts to lose a little bit of its charge every day. However, I've never found any info about whether new--or relatively new--NiMHs can lose their ability to hold a charge.

If it got to the point where I was using a set or two at all, would those sets essentially go back to the state they were in when I got them new...needing a few conditioning cycles to get them in to operating condition? Or would they be in a worse state?

As I'm sure you can tell, I just want to make that I don't have to toss away any of my battery sets simply because I wasn't using them. Right now, I'm just rotating all of my 5 or 6 battery sets through the camera, but I'm hoping to hear that I don't have to do this...please

Any help you kids could give me would be greatly appreciated Thanks.

--
Kevin

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Olympus C-5050Z

McKev25 said:

I wrote:
If it got to the point where I was using a set or two at all, would
those sets essentially go back to the state they were in when I got
them new...

Click to expand...

I meant to write:
If it got to the point where I WASN'T using a set or two at all, would
those sets essentially go back to the state they were in when I got
them new?...

--
Kevin

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Olympus C-5050Z

McKev25,

Good question. I have no idea what the answer is, but I too have many sets of batteries. I just retired a set I started using three years ago: the Kodak batteries from my DC280Z! I just rotate them, set-by-set through my various cameras and flash units. All get a "fresh" charge just before a big shoot or a trip. Never had a problem.

Cheers,

jim

--
galleries at: http://www.pbase.com/sandman3

Unfortunately, I don't know the answer, and I don't remember seeing it answered on any of the many battery info sites.

Maybe someone has actually tried not using a set of NiMh for a couple of years, and can tell us what their experience was.
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• Eric, http://www.InvisibleRobot.com/

From what I've read both NiMH and Lithium Ion batteries lose about 1% per day so after 1 month they are down to around 70% of the initial charge. So best to do a final top-up of all batteries before an outing.

However, if leaving batteries unused for long periods (maybe a couple of months or more) then it is advised that they be left in the flat state. Discharge before storing.

If left charged and they do the usual 1% per day loss then somehow they start to lose ability to hold full re-charges. With normal charge-discharge cycles in reasonable time periods it seems the memory effect is not a problem, it only seems to come into play when they do that long slow self-discharge.

Haven't tested any of this for myself but seemingly sensible battery sites repeat this info. Here's one for you to check out in their FAQ somewhere.
http://www.batterysupply.com/

My problem is that the initial set of NiMH batteries that I bought worked fine for the first few full charge-discharge cycles but within a short time they hardly hold a decent charge at all, even though they seem to take the full xx hours to re-charge (depends on whether slow or fast charger I use). They may have the capacity but they either seem to self-discharge faster than before or they have developed more internal resistance and can't supply the high current for long periods. Don't know, but they soon will be land-fill. (From now I use a better brand, cheapies are not worth looking at).

I repeat to all new-comers to digital cameras... batteries are the real pain area.

Regards................. Guy

From:
http://www.cliffshade.com/dpfwiw/batteries.htm#self-discharge

"Freshly charged NiMH batteries are commonly said to lose 10% of their capacity in the first 24 hours and 1-2% daily thereafter at room temperature. (High ambient temperatures speed self-discharge while cool temperatures slow it.) At a conservative 1.5% per day after the 1st day, that leaves a residual charge of 58% at the end of the first month. If you're coming down from, say, 1600 mAh, the remaining 928 mAh per AA will still power quite a few shots. And to put that into perspective, recall that 1200 mAh rechargeable AAs were considered "high-capacity" not so long ago."
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Olympus C5O5O, B-twenty eight, B-3OO, FL-4O

That has nothing to do with the question. We all already knew that.

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• Eric, http://www.InvisibleRobot.com/

I haven't read anything that said you should leave batteries discharged if you plan to store them for a long time. Can you please point to a specific place that has this information?

--

• Eric, http://www.InvisibleRobot.com/

--
Kevin

*********************************************************
Olympus C-5050Z

Guy- Thanks for the info. However, I wasn't able to find an answer to the question I am asking on the site you mentioned, nor on any other site. I will have to keep looking.
--
Kevin

*********************************************************
Olympus C-5050Z

Eric- I mostly want to know just out of curiosity, but I also want to know because I of course don't want to waste any of my many batteries.

I guess I could just contact Maha, and see what they say.

Thanks.
--
Kevin

*********************************************************
Olympus C-5050Z

--
Kevin

*********************************************************
Olympus C-5050Z

In addition to the useless stuff I wrote, I've been using NiMH batteries that are 3 1/2 years old. One set is the, I believe 1100 MAh ones that came with my 2020. I retired the 2020 when the detents of the program knob gave out this spring and I bought a 5050.

I've been doing a macro shoot using two external flashes and am powering the flashes with the batteries I bought for my 2020 ( I bought 3 sets). I've also been using the 2020 to document the setup using the 3+ year old batteries.

I don't have any numbers on remaining capacity, but I've fired the flashes at least 40 times and they recycle very quickly using the old batteries. The 2020 is working fine on them too.

At least we know they're not totally bad after 3 1/2 years.

--
Olympus C5O5O, B-twenty eight, B-3OO, FL-4O

I've got some 20+ year old Nicads somewhere. I wonder if they still work. Not that I would try to use them for anything. I guess I should try to find them, and take them to the local battery disposal facility.

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• Eric, http://www.InvisibleRobot.com/

Reading the FAQ on this site should give you your answer about documentation for storage:

http://faq.alltekpower.com/faq/index.asp?a=4&q=21

to quote "3. Always store your NiMH batteries in a Discharged state."

I was also wondering if using rapid chargers would in any way decrease the max charge of a battery. I have a rayovac 1 hour charger and wonder if I should occassionally use one of the slow chargers that I have to recharge them or does the rapid charger do a better job?

Thought there might be some interest in this 15 minute rapid charger from Rayovac expected out in Oct 2003:

http://ir.thomsonfn.com/InvestorRelations/PubNewsStory.aspx?partner=MzgwTVRZNVAkWQEQUALSTOEQUALSTO&product=MzgwU1ZJPVAkWQEQUALSTOEQUALSTO&storyId=80093

any thoughts?

Interesting, but it seems you have to use their special batteries in addition to the charger as some of the charging "smarts" are embedded.

I wonder if it includes the liquid nitrogen cooling system that'll be needed. ;-)

Tom Pfennigwerth said:

Thought there might be some interest in this 15 minute rapid
charger from Rayovac expected out in Oct 2003:

http://ir.thomsonfn.com/InvestorRelations/PubNewsStory.aspx?partner=MzgwTVRZNVAkWQEQUALSTOEQUALSTO&product=MzgwU1ZJPVAkWQEQUALSTOEQUALSTO&storyId=80093

any thoughts?

Click to expand...

Inigo Montoya said:

I wonder if it includes the liquid nitrogen cooling system that'll
be needed. ;-)

Click to expand...

Naw, but there is an optional kettle.

Sandman said:

McKev25,

Good question. I have no idea what the answer is, but I too have
many sets of batteries. I just retired a set I started using three
years ago: the Kodak batteries from my DC280Z! I just rotate them,
set-by-set through my various cameras and flash units. All get a
"fresh" charge just before a big shoot or a trip. Never had a
problem.

Click to expand...

I had two 1300 mAh NiMeHydride batteries that failed, but all the others have been fine for up to three years. I now use them in a radio that gets used every day. But I don't rely on them in emergency flash lights. The self-discharge is not too bad in regularly used equipment though.

The problem was big with Nickel Cadmium batteries, which needed full cycles to remain alive. My NiCads in handheld transceivers were always kept at full charge in a power supply unit, so they often died when I needed them for portable use.

Henry

--
H. Falkner

Eric Carlson said:

I haven't read anything that said you should leave batteries
discharged if you plan to store them for a long time. Can you
please point to a specific place that has this information?

Click to expand...

A few bits that are interesting off the FAQ found at Thomas Distributing via the http://www.batterysupply.com/ FAQ mentioned above.

"Generally speaking, NiMH batteries do not suffer from the "memory effect" and thus do not require conditioning. Nevertheless, to ensure top performance, conditioning is recommended at once for every ten charges."

And follow the "about NiMH batteries" link at the bottom of the page at http://www.batterysupply.com/ and you find some more stuff....

This was at http://faq.alltekpower.com/faq/index.asp?a=4&q=21

"Yes, here are some tips for storing your NiMH Batteries:
1.Always store your batteries in a cool dry place.

2. Do not expose your batteries to direct sunlight or temperatures below 30 degrees F or above 95 degrees F during storage for prolonged periods of time.
3. Always store your NiMH batteries in a Discharged state ."

And at http://faq.alltekpower.com/faq/index.asp?a=4&q=17

"At normal room temperature, NiMH batteries can generally retain 70% of their charge after 30 days. Normal self discharge of NiMH batteries is about 1 percent per day at normal room temperature. Of course, environmental factors and higher temperatures will play an important role in the above said value and will cause NiMH batteries to discharge at a slightly higer rate. Lower temperatures ( 40° to 60° F ) on the other hand will cause NiMH Batteries to hold their charge longer."

I've seen similar stuff elsewhere but can't put my finger on it right now.

Regards...... Guy