NiMH AA Batteries? Can someone explain?

[Marek K]

My wife has an IkeLite PCa. Great light but eats batteries.
[...] At 60 minutes into the dive, the light, while dim but
still in use, exploded underwater.
Nice loud "pop" and blew the lens top right off the light.

Same thing happened to me with my PCa a couple years ago. I was using it during a day dive, and had it in a BC pocket while surfacing. The lens assembly popped right off, damaging the latching lugs slightly.

It happened to someone else, too.

I also think it had to do with off-gassing of hydrogen... I'd had the light on during the whole dive. I think the outside pressure reduction while surfacing had something to do with it too. Plus, the latching mechanism on the PCa doesn't seem to be very strong.

I saved the light. I agree it's a great little light. And I still use rechargable NiMH batteries in it; can't afford NiCad AA's at that rate. but I just turn it on when I need it. And I take it along as a night dive back-up.

--Marek

 

[DandyDon]

Ok, I was really looking for basic help here...?

(1) Slow charging is better than fast charging, agreed...?

(2) What about discharging the batteries now and then. Looks like some of the info says to not drain them fully?

(3) They don't seem to have as good of storage capabilities as non-rechargables, do they?

(4) I just charged 2 - 2200 mah batteries, dropped them into my Canon A540, and it said weak batteries? Expected, or bad batteries...?

 

[Footslogger]

This article hasn't been updated since 2005 but the basic science hasn't changed ...only the maximum current of the NiMH batteries.

http://www.imaging-resource.com/ACCS/BATTS/BATTS.HTM

I'm using the 2700 mAH Powerex batteries in my C5050Z with excellent results. I use a MAHA charger that takes about 2 hours to fully charge the AA cells. It also has a "conditioning cycle" that fully drains and then recharges the cells if necessary.

I have 4 sets of AA cells and keep them charged. One set of 4 AA's gives me full performance for a dive (camera is on and functioning - including LCD screen - for over an hour) and then I swap sets of batteries during my surface interval (and place the ones coming out of the camera into the charger).

 

[RonFrank]

Ok, I was really looking for basic help here...?

(1) Slow charging is better than fast charging, agreed...?

(2) What about discharging the batteries now and then. Looks like some of the info says to not drain them fully?

(3) They don't seem to have as good of storage capabilities as non-rechargables, do they?

(4) I just charged 2 - 2200 mah batteries, dropped them into my Canon A540, and it said weak batteries? Expected, or bad batteries...?

Hey Don,

1. No. Good charging is the key and for that you need a charger that is designed for NiMH batteries, i.e., senses heat, does not overcharge. Mine monitors the batteries, and goes into a trickle mode when the batteries are full charged.

2. Do NOT drain NiMH batteries. NiCads have memory, full draining them followed by a full charge helps reduce memory fatigue for lack of a better word. NiMH are not NiCAD's, and do not need to be refreshed.

3. My NiMH batteries seem to loose maybe 20% of their power a week regardless of if I'm using them. I keep my NiMH's charged, and charge them weekly even if I'm NOT using them. They are good for about 1000 charges, so 1000 weeks, I can live with that!

4. Just checked the A540 is NiMH recommended, and newish. A standard NiMH puts out 1.2V. A standard Alkaline is 1.5V. You either you have bad batteries, a bad charger, or a screwed up camera. My bet would be either the charger or the batteries. All charges are not created equal. MAHA chargers are some of the better ones on the market, or at least were highly recommended when I purchased mine.

Try this with some different batteries.

Lithium batteries are awesome. Lightweight, powerful, work well in cold weather. However they are disposable, expensive, and did I say.. Disposable!

For devices like remote controls I use Alkaline as they will hold a charge for years, and remotes don't use much power. For Digital I use NiMH for flash power, and whatever proprietary battery for things like my DSLR's, UW Strobes, etc.

My Major Beef is WHY OH WHY can't someone come up with ONE charge system that charges all this stuff! I run around on trips with a suitcase of battery charges, and cords! It's just WRONG!

 

[do it easy]

Ok, I was really looking for basic help here...?

(1) Slow charging is better than fast charging, agreed...?

(2) What about discharging the batteries now and then. Looks like some of the info says to not drain them fully?

(3) They don't seem to have as good of storage capabilities as non-rechargables, do they?

(4) I just charged 2 - 2200 mah batteries, dropped them into my Canon A540, and it said weak batteries? Expected, or bad batteries...?

(1) fast charging is better!

(2) ok to discharge the batteries, but not all the way- I think down to 1v per cell is OK, but below that, polarity reversal (bad thing) could occur. NiCd batteries are more robust when it comes to deep discharges.

(3) They will self drain if left to their own devices. A quick charge before use will fix this.

(4) NiMH batteries operate on a lower voltage than Alkaline or primary lithium cells. So if you camera is expecting 3v, but your batteries are putting out 2.4v, it's gonna think that it's low. NiHM and primary lithium batteries can't always be substituted for alkaline, depending on the device/application. It sounds like they aren't gonna work in your camera.

On a side, note, I just converted a 3 C-cell flashlight to run off of 4 4/5 sub C NiHM cells so that I could get the voltage required to drive the LED module.

 

[DandyDon]

NiHM and primary lithium batteries can't always be substituted for alkaline, depending on the device/application. It sounds like they aren't gonna work in your camera.

The camera works fine on Lithium non-rechargables.

 

[do it easy]

NiMH cells have a nominal voltage of 1.2v, alkaline are 1.5v, and lithium primary are 1.8v (I think this is open voltage and the rely on the resistance of the device to bring the voltage down to 1.5v). Some devices can't handle the 1.8v (like the bperrybap's flashlight), while others can. It seems like your camera can. Is there anything specific in the instruction manual about what kinds of batteries to use?

 

[RonFrank]

The camera works fine on Lithium non-rechargables.

Don,

You may need to do some research, and some testing. Here is something to note from Imaging Resource.

The Importance of the Charger (!)

One of the most interesting things I found was that the right (or wrong) charger can make a difference of nearly 2x in the results! The worst chargers (in terms of completeness-of-charge) produced "charged" batteries with only half the stored energy of ones charged with the best chargers. Interestingly though, the best overall results were obtained by combining the worst fast-charger with an inexpensive trickle-charger for topping-of and charge maintenance. - This combination was also the gentlest on the batteries. (Stay tuned for a detailed overview of battery chargers as I can get to it. For now, you can just take as given that the Maha C204 charger was among the most consistent I tested, and charged the batteries to close to their maximum capacity every time. To insure that the batteries were *totally* topped-off, I always gave each set at least an overnight trickle charge as well though..) The Lightning 4000 charger sold by RipVan100 was also very good - It was more gentle during the charge cycle, but took longer to charge the cells than the C-204, and didn't charge them quite as fully as the 204, even if left overnight. The difference in charged capacity was rather slight though.)

I own the 204 charge, and it has worked great for years. I'm thinking of buying a second as a backup. The fact that SOME chargers on the market only charge a battery to 1/2 of it's capacity is rather notable!

 

[lazyturtle]

The issue with rechargable batteries is that as you charge them, they lose the ability to retain as full of a charge (if that's not clear I mean that as you regularly recharge them that the 'full' ammount decreases over time).
Ion-Lithium batteries are the 'best' because this does not occur. Every time you charge a ion-lithium it will charge to the same ammount....until it does not. Once it's charge levels decrease, it's done. Some studies have shown that they lose as much as 20% capacity per year (assuming constant use) and that to prolong thier use life you can store them in the fridge. Another problem with IL batteries is the potential for fire (you've heard of laptops bursting into flames? Flood a digital camera with a IL battery adn the same COULD happen). ILs are also lighter.
NiMH batteries lose their maxium capacity regularly over time. The each charge will reduce the maximum charge by a little bit, until one day the batteries are useless.
If you really want the low-down find a college chemistry book, and it will explain the differences and capiblities of each battery in great detail.

 

[Footslogger]

I own the 204 charge, and it has worked great for years. I'm thinking of buying a second as a backup.
=================================

I've got the 204 as well and no complaints. From my experience I would highly recommend it.