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Kite Land Talk => Website Discussion => Topic started by: Zeke on May 16, 2010, 02:04 PM

Title: Nimh question
Post by: Zeke on May 16, 2010, 02:04 PM
I have 3 sets of AA that all seem to go dead within a week or so while sitting in the camera bag. I though Nimh were supposed to keep their charge.  Al are AA, either 2650mah or 2000mah bought in stores locally like CVS or WalMart.  Charger is for up to 8 AA or 8AAA and is a  radio shack #23-422.  Camera is a Fuji S700.  Thoughts or suggestions?

Title: Re: Nimh question
Post by: fidelio on May 16, 2010, 02:26 PM
how long have you had them, and how many times have you charged them?
all rechargeables have a lifespan so if you've used them consistently for a year or more it's likely they're reaching the end of their life-cycle.

as great as the manufacturers claims for duty rating are, they rarely meet them. the sad truth is, you sometimes just have to start over with fresh batteries.

a new rechargeable nihm battery, properly and fully charged, should only lose about 1% charge per week, but a worn out one can lose most of it in a couple of days.

if your batteries are newer, please disregard my comments.

Title: Re: Nimh question
Post by: Jeepster on May 16, 2010, 05:01 PM
In practice, the older style of NiMh cells seem to discharge at a much higher rate than advertised.  If you're charging and using them all the time, you don't notice that problem.  But, if you let them set for quite awhile (especially when the cells get some age and cycles on them) than the problem becomes very noticeable.  I just threw out about two dozen cells that only charged to about 75% of capacity ... that seems to be the point at which they're not worth the trouble to have in your stock.  Two of those cells would self discharge to an unusable condition within three days.

For replacements, I bought some standard EverReady NiMh cells and some Sanyo Eneloop cells.  I don't have enough experience with the Eneloop cells to give a glowing recommendation.  However, from a limited three month experience, I'll only be buying the Eneloop cells in the future.  There are some other brands on the market, but the Sanyo cells seem to be the only ones made in Japan ... the other brands are manufactured in China.

These newer cells come precharged from the factory ... how's that for maintaining a charge.  They are advertised as maintaining 85% of their charge after one year in storage.  I haven't checked it out, but can believe it's true.

I don't have knowledge of the Radio Shack charger, so these comments are not directed at it.  Fast charging your cells will shorten their life ... heat is the enemy of longevity.  If you want reliable, long life from AA NiMh cells, then a 500~750 mAh charge rate is recommended.  Most of my charging is done on an older La Crosse BC900 charger set to 500 mAh.  That rate helps keep the cells very cool.  Some of the cells I threw out were over five years old and had seen lots of cycles.  Nowhere near the 1000 cycles that are advertised though ... you do know that's under carefully controlled laboratory conditions with lots of babying, lots of luck and maybe a little fibbing.


Title: Re: Nimh question
Post by: ko on May 16, 2010, 06:33 PM
if you buy the type that say's pre charged i have found they are pretty much similar and they definatly hold a charge longer ..try completly discharging and then charging the batteries you have now, some of the older type have memory,and this will allow them to fully charge. i use the rayovac hibrid they seem to work better than anything i have tried walgreens has the AA's on sale 4 for about 10bucks

Title: Re: Nimh question
Post by: xuzme720 on May 16, 2010, 08:26 PM
Not sure the cycle will help. NiMH don't have the memory Nicads had that discharge/recharge would erase. If they are going dead that fast, they are probably kaput. I use NiMH's in my flash and they sit in the camera bag for weeks and sometimes, months, before I use them. Unless you keep them in the camera (I had a P/S camera that killed batteries even when off), I would just replace them...

Title: Re: Nimh question
Post by: mikenchico on May 16, 2010, 11:33 PM
The older ones definitely did discharge quickly, my first set in my first digicam would be dead in a week, in or out of the camera. The newer ones hold a charge better. I was surprised to see those fully charged ones for sale after my experiences, guess I won't laugh if you guys say it's true. Might be time to replace them, if they are the older ones it's definitely time.

I don't know how you would do it but you might check your charger, I had one that had problems and was eventually recalled by the manufacturer, but after destroying a couple sets of my batteries.

That 4 for $10 above with a positive review is a good deal, probably be checking that out myself, one of the batteries in one of my sets is dead, I'll kick down two of the good ones to Rhonda since her cam only needs two, mine uses four.

Title: Re: Nimh question
Post by: chilese on May 16, 2010, 11:40 PM
When I bought AA chargeable batteries and chargers, this was my store of choice. (

Title: Re: Nimh question
Post by: zippy8 on May 16, 2010, 11:51 PM
Not sure the cycle will help.

Cycling may not help but balancing a set of batteries might well be of use.

If you discharge and recharge each cell individually you may be able to match them into groups of cells that perform at similar levels so that one or more cell doesn't overdischarge in use when others are still doing fine.

Admittedly you'll need something a bit more high tech. than a plug in wall charger. I personally rock a Robitronics Overloader 2 ( for all my considerable recharging needs. It's brought several packs back to usability already but isn't magic and cells that are damaged (ie; failing to hold a charge) aren't going to be resurrected.


Title: Re: Nimh question
Post by: chilese on May 17, 2010, 12:47 AM
Mr. Emery, do you do anything normally?  ???

Title: Re: Nimh question
Post by: zippy8 on May 17, 2010, 12:48 AM
By my standards, yes.

By those faulty ones of the world around me, possibly not.


Title: Re: Nimh question
Post by: theodocius on May 24, 2010, 11:46 AM
I'll second Chilese's Thomas Distributing recommendation.  For nearly two years I have been using the MAHA MH C801D 8-cell AA charger, and MAHA Powerex 2700 AH AA batteries.  Great performance, and no replacements required yet.  IMHO, a great charger is required for max. performance and battery life.  I use these things in Dinotte LED lights, a high-drain application for night-time bicycling, and sometimes in a camera.


Title: Re: Nimh question
Post by: biglos on May 24, 2010, 02:03 PM
Also keep in mind that a lot of cheaper devices eat batteries even when they are turned off. I am noticing most baby toys that take batteries are terribly inefficient. Its enough to wonder if those toys are made by the battery companies.