NiMH rechargeable batteries

[Muse]

Don't know when they developed NiMH recharge batteries. Rechargeable battery technology has evolved, however it used to be that NiCads had longevity issues. Obviously they still do and so do NiMH batteries. Specifically, Nicads could possibly be recharged up to 500 times or more and they seemed to have a life expectancy in years - something like 5 years and you would notice that they didn't seem to hold as much charge as they used to. I see that they market NiMH batteries nowadays saying that you can possibly recharge them as many as 1000 times. I'd like to get some deeper knowledge about the issues.

1. Do NiMH batteries have a life expectancy? Are 5 good years (or 7 or 10) all you can "reasonably" expect out of them?

2. Do NiMH batteries have a shelf life? What happens if I put some new NiMH in a drawer and don't use them? Will they be the same in 5 - 10 years or will they have become relatively useless just sitting there? They used to say that NiCads did better when you used them frequently. NiCads have the famous memory effect, and evidently less so NiMHs. I figure that it's best to have a conditioning charger (optionally discharges cells before charging them, pretty essential for NiCads and at least occasionally for NiMHs), or a device that similarly safely discharges them (but not below around 1.0v).

I've read some FAQs, but haven't found anything that appears definitive. I have a booklet I got years ago about NiCads, and it helped me understand the issues pertaining to them, at least 10-12 years ago, but I haven't yet found something like that for NiMH. I figure there's something on-line that would provide similar in depth semi-technical information. Does anyone know some good links? Thanks.

 

[0roo0roo]

http://www.dansdata.com/gz011.htm


search site for more on nihm.

buy rayovac 15 min nihm and stop worrying about it.

 

[Muse]

Originally posted by: 0roo0roo
http://www.dansdata.com/gz011.htm


search site for more on nihm.

buy rayovac 15 min nihm and stop worrying about it.

Hmm. Advice, huh?

I read Dan's spiel linked above. I've read at least one other piece by him. He's smart but also very much the smart-ass, and I find this piece of very questionable merit. Impossible to sort out the truth. He's obviously heavily opinionated but he does little to nothing to put reason into his analysis. He may be entirely right about his premises, but I'd be an idiot to take his word for it. There HAS to be a lot better stuff around by people without peculiar attitudes, and I have to class his "peculiar."

Edit: I mean what can you expect from a piece entitled "Dan's Quick Guide to Memory Effect, You Idiots"??

 

[0roo0roo]

he does plenty more smart assing in letters he answers, just use the search on his site.

 

[Muse]

Originally posted by: 0roo0roo
he does plenty more smart assing in letters he answers, just use the search on his site.

Ya, know, I don't see a search on his site. Just Google and Dealtime searches. Also, his references are only concerning NiCads, not NiMHs. He DOES have a page listing his Articles and Tutorials and I guess I can search the list... Well, there are no hits for nimh.

 

[0roo0roo]

the google option has a search dansdata.com only.

http://www.google.com/custom?hl=en&ie=UTF-8&cof=AWFID:c047247881a20119%3BL:http://www.dansdata.com/images/cornlogo.GIF%3BLH:97%3BLW:178%3BAH:center%3B&domains=dansdata.com&sitesearch=dansdata.com&q=NIMH&spell=1

nihm google search

 

[Muse]

Yes, that works. All this stuff other than the "You Idiots" article is tangent to the topic. He's not discussing the topic in detail, just as seems appropriate the specific question addressed in these letters. I'm looking for a good reliable in-depth source for information about NiMH AA and AAA cells and chargers. Dan's apparent contention that conditioning these cells significantly reduces their life is something I've not seen anywhere else (quite the contrary, it would seem) and I wonder if he's right or wrong.

 

[Evleos]

If you're able to read Norwegian: http://www.akamera.no/art.php?artikkelid=1295

There?s a battery guide regarding cameras, it includes the differences between NiMh & NiCd.

They say about Nimh

*Not poisonous, at least not in comparison to NiCd
*Twice the energy density in comparison to NiCd
*They don't claim any differences between NiMh & NiCd in amount of recharges
*They claim that experience has shown that it is not favourable to drain all the power out of the NiMh battery before recharging.
*They don't point out any differences between NiCd & NiMh in battery life, both is 10+ years.

 

[JImmyK]

bottom line from my PERSONAL experience which is corroborated by what educated people say

NIcD- Do have a memory issue and are more punchy
NImH - longer life in general, I never have to drain them and recharge them

as you can see from my collection I have been thorugh quite a few batteries, and this is only half my collectionI have a buncha dead nicds sitting in my closet.

http://filebox.vt.edu/users/jkhan/IMG_3031%20(Large).JPG

 

[Muse]

Originally posted by: JImmyK
bottom line from my PERSONAL experience which is corroborated by what educated people say

NIcD- Do have a memory issue and are more punchy
NImH - longer life in general, I never have to drain them and recharge them

as you can see from my collection I have been thorugh quite a few batteries, and this is only half my collectionI have a buncha dead nicds sitting in my closet.

JimmyK's collection

Looking at that pic I see you also have the Winfast TV card (I recognized the remote!). By saying the NiCads are more punchy I suppose you mean they give short bursts of greater energy than the NiMH. I'm not sure that's true. They say you don't have to drain the NiMH to get full capacity but unless you do drain them periodically (maybe once a month) they will lose some capacity, moreso than if you "condition" them occasionally. I've read posts from people who say a conditioning charger has revived some NiMH's. I'm contemplating the Maha C204F charger, which is an optionally conditioning charger. I'm also wondering if it's worth it to also get 8 Powerex 2200 mah NiMH in the bargain. It seems like more batteries than I need right now, but if they have a shelf life or can be expected to last 10+ years in occasional rotation it would be more worth it.

 

[Muse]

Originally posted by: Evleos
If you're able to read Norwegian: http://www.akamera.no/art.php?artikkelid=1295

There?s a battery guide regarding cameras, it includes the differences between NiMh & NiCd.

They say about Nimh

*Not poisonous, at least not in comparison to NiCd
*Twice the energy density in comparison to NiCd
*They don't claim any differences between NiMh & NiCd in amount of recharges
*They claim that experience has shown that it is not favourable to drain all the power out of the NiMh battery before recharging.
*They don't point out any differences between NiCd & NiMh in battery life, both is 10+ years.

No, my Norwegian is as weak as can be imagined. My iRiver SlimX IMP-350's instruction manual says I'll get longer life out of the included NiMH batteries if I condition them once a month. They are a proprietary 1.2v design (flat), but otherwise I suppose they are like ordinary NiMH batteries. The SlimX features charging via a wall wart that plugs into the unit and also features an optional discharge before recharging the batteries - what's called conditioning. I've read a very similar thing elsewhere concerning NiMH AA batteries - that monthly conditioning will extend their life (and I think, possibly, tend to maximize capacity).

The 10+ years is a welcome concept. I'd read 10-15 years ago (before NiMH batteries were in use) that NiCads only lasted 5 years before they started to go bad, regardless of other factors. Maybe they've improved them. I hadn't heard ANYTHING prior to reading what you say here concerning the life expectancy in years of NiMH batteries.

 

[Mark R]

The life of consumer grade rechargeable batteries, is very much limited by poor quality chargers, and poor matching of cells within a pack.

Overcharging (most fast chargers will overcharge to some extent) kills batteries quickly, particularly if charged quickly. High-voltage battery packs (e.g. 6V or higher) should not be deep discharged or 'conditioned' because you run the risk of 'reverse charging' a weak cell - and that will kill it even faster than overcharging. Poor quality 'battery fuel-guage' systems give the illusion of 'memory' if the battery is shallow cycled (the battery has the power, but the device thinks it is flat).

I remember my old cell phones with NiCd batteries - I'd need a new pack every 6 months, because it would only last about 8 hours standy instead of 24. New devices use NiMH or Li-ion batteries which are far more fragile than NiCd, yet the batteries last much, much longer - testament to decent charge/discharge control systems.

Industrial batteries should be able to last 10 years, but whether cheap mass-produced domestic grade batteries can is open to debate. All rechargeable batteries are physically fragile (this is a particular problem with extra-high capacity ones) drop one, and you can damage it reducing its capacity or causing it to lose charge quickly.

For what it's worth, specially designed NiCD batteries for ultra-reliable UPSs are probably the most reliable, longest lasting batteries available - with zero risk of sudden failure, and an expected 20 year life-time.

 

[Muse]

Mark R - It looks like you are into digital photography. This is my main immediate usage, really, although I'll also use them in a cassette walkman and possibly in flashlights. What do you use for batteries and a charger (I assume you use rechargables)?

I'm considering the Maha C204F combination with the Powerex 2200 mah AA's. That charger has optional conditioning.

 

[Mark R]

I have surprisingly little use for batteries.

My gadgets all have proprietary Li-ion batteries, which seem to work perfectly well - and have sufficient capacity that I do not need to carry a spare.

I have a few NiMH batteries, and a 15 year old NiCd trickle charger which I use with a handheld GPS unit - I get 16 hours on a charge, so the fact that it takes 30 hours to charge a set doesn't really matter.

 

[0roo0roo]

Originally posted by: Muse
Yes, that works. All this stuff other than the "You Idiots" article is tangent to the topic. He's not discussing the topic in detail, just as seems appropriate the specific question addressed in these letters. I'm looking for a good reliable in-depth source for information about NiMH AA and AAA cells and chargers. Dan's apparent contention that conditioning these cells significantly reduces their life is something I've not seen anywhere else (quite the contrary, it would seem) and I wonder if he's right or wrong.

oh, he provides good links in some of those letter answers. i've seen answers to your questions before, but i don't remember much, and well i wasn't going to dig for u.

 

[Muse]

Originally posted by: Mark R
I have surprisingly little use for batteries.

My gadgets all have proprietary Li-ion batteries, which seem to work perfectly well - and have sufficient capacity that I do not need to carry a spare.

I have a few NiMH batteries, and a 15 year old NiCd trickle charger which I use with a handheld GPS unit - I get 16 hours on a charge, so the fact that it takes 30 hours to charge a set doesn't really matter.

A Li-on battery came with my new digicam, but it's not rechargable. They have a rechargable Li-ion kit available but it's around $100! I figure I'll do better using NiMH's. Like I say, the Maha C204F with 8 x Powerex 2200 mah is at the top of my list but I'm going to keep doing research before buying. I have several chargers including a NiCad trickle charger that I could use instead, but the conditioning is something I figure might be worth it. It's not easy finding out about NiMH's online, at least that's my experience of the last couple days.