Rechargeable Batteries

[Bigaldoc]

This is a very embarrassing question but I've gotta ask it anyway. It's about rechargeable AA and AAA batteries.

A few years ago, at the recommendation of a fellow Lounger I bought several AA and AAA rechargeables and a charger to go with it. I use them in cameras, mouse and a couple of other devices except my wireless keyboard. I have a few that are rated 2450 mAh and some more at 2900 mAh.

Is there a danger of "ruining" batteries if you leave them in the charger too long? I usually put two or four in for charging and sometimes don't remember to take 'em out the next morning, so they sit there for 2-3 days.

I've now started encountering some that, freshly charged, and placed in a camera still flash as needing to be charged. I don't know if I've ruined the batteries by overcharging or if the el-cheapo charger I bought is near (or at) death. Any comments?

[Sundog]

Don't know about too long in the charger, but I believe most (all?) rechargeable batteries perform better if they are occasionally discharged almost completely?

[StuartR]

This really depends on the quality of the charger. A good charger will detect that the batteries are fully charged and stop charging them.

Also there are different kinds of rechargeable cells. Some of the newer ones are able to hold their charge for a long time after being charged, whereas the older ones rapidly lose their charge when they are not used.

[Bigaldoc]

Thanks, Sundog. I don't know how to judge "discharge level" except that when the device (camera, mouse, etc.) tells me that the batteries are weak, I usually respond immediately.

[Leif]

Have they ever worked in the camera, and is the camera specified as being suitable for rechargeable batteries? Ni-Cads, I think, have a terminal voltage of 1.2V, non-rechargeable types 1.5V. If your camera uses two, that's 2.4V instead of 3V.

Is there a danger of "ruining" batteries if you leave them in the charger too long? I usually put two or four in for charging and sometimes don't remember to take 'em out the next morning, so they sit there for 2-3 days.

To a great extent, that depends on the charger, and how intelligent it is. A good one will do a fast charge and then either turn off or switch to a trickle charge.

And then of course it depends on how many times you have recharged the batteries, and how many re-charges they are rated at....

[Bigaldoc]

This really depends on the quality of the charger. A good charger will detect that the batteries are fully charged and stop charging them.

That may very well be my problem since it will sit there for days with the green lights on. What I don't know is whether that has "ruined" the ability of the batteries to hold a charge at all.

Also there are different kinds of rechargeable cells. Some of the newer ones are able to hold their charge for a long time after being charged, whereas the older ones rapidly lose their charge when they are not used.

I was planning to attend a function at the nursing home this afternoon (Halloween Party) so I, as usual, checked my camera and when I turned it on, I got a battery low warning. Popped out the two that were in there, and THEY were charged within the past week. Put in two fresh ones that had just been charged a few days ago. Same story - battery warning.

I popped in a couple of non-chargeable alkalines so I could make my trip. While waiting for comments here, I just located a charger at Amazon that DOES say it will stop charging after eight hours.

Ironically, the ones that are giving me this problem are 2450 mAh Energizers which should (I think) be a reputable brand. So, once again, I don't know if I've ruined them by overcharging. I only have a few 2900 mAh that have a brand name of Power2000 which I've never heard of and those seem to be OK (so far).

[StuartR]

I think Leif may well be right about this. I have a wireless keyboard that takes two AAA batteries. It doesn't work at all with rechargeable cells. Has your camera ever worked properly with rechargeable batteries?

[viking33]

How old are these batteries, Al?
I know you said a few years ago but they don't last forever either. After many charges/discharges, they just don't have the "get up and go" to charge fully OR at all. ( something like people )

Also, some Ni-cads develop a low voltage memory and will only charge to a certain low voltage and that's that.
An old trick I used to use, was to use a 12 volt DC power supply. and just give the batteries a QUICK shot of 12 volts, positive to positive, negative to negative. It usually would blow away the memory and you could recharge them again fully. Didn't always work but usually it did.

I know, I can hear the gasps from some out there. Engineers have more fun!

[Bigaldoc]

I think Leif may well be right about this. I have a wireless keyboard that takes two AAA batteries. It doesn't work at all with rechargeable cells. Has your camera ever worked properly with rechargeable batteries?

I too learned from Leif at the time I started using rechargeables that my wireless keyboard demands more "power" than they will provide, so I use regular throw-away alkalines in the keyboard.

But yes, my two cameras have always worked flawlessly with the rechargeables.

Maybe Bob is onto something... See next post.

[Bigaldoc]

How old are these batteries, Al?
I know you said a few years ago but they don't last forever either. After many charges/discharges, they just don't have the "get up and go" to charge fully OR at all. ( something like people )

Also, some Ni-cads develop a low voltage memory and will only charge to a certain low voltage and that's that.
An old trick I used to use, was to use a 12 volt DC power supply. and just give the batteries a QUICK shot of 12 volts, positive to positive, negative to negative. It usually would blow away the memory and you could recharge them again fully. Didn't always work but usually it did.

I know, I can hear the gasps from some out there. Engineers have more fun!

You may have hit the nail on the head, Bob! I looked in my emails and these Energizers were bought in December 2008, so maybe, like cell phone batteries (sometimes) they've seen the end of their useful life. I don't have the equipment to do your workaround, so I guess I'll buy some replacements, both batteries and the more "intelligent" charger I mentioned earlier.

This time, I think I'll use more care and look for some 2900 mAh batteries since the few I have, that were bought about the same time, are still working OK.

Battery technology, in all genres, leaves a lot to be desired and I'm admittedly NOT en engineer so I don't have the right to gripe except as a consumer. My classic example, over the years, has been electric razors which seem to go belly up much quicker than their price should merit. Gggggrrrrr...

[StuartR]

If you're going to buy new batteries then I would recommend looking at ReCyko. These seek to be much better than the older style of rechargeable batteries.

[Bigaldoc]

Thanks Stuart. I'll have to look. I see that they're available via Amazon.

[ChrisGreaves]

This is a very embarrassing question but I've gotta ask it anyway. It's about rechargeable AA and AAA batteries.

When the number of rechargeable batteries in your household exceeds the years of your life, you got problems.
Until then you might adopt Greaves's Rechargeable Rules ("Grr!").
Identify rechargeable batteries by year-of-purchase (close enough for government work). In Binary perhaps.
Use the older batteries in non-essential devices, such as the TV remote control or the battery-powered clock in the basement.
Use the newer batteries in essential devices such as the camera-at-a-wedding, or the battery-powered clock by which you judge the time of passing of the bus for downtown, or the bedside alarm clock.

If I were anal-retentive I'd keep a little diary and track how long each battery lasted per charge in each device ....

[Claude]

Any rechargeable battery that plays up in our household gets the following treatment which, without fail, fixes the problem:

discharge the battery completely.
put batter in freezer overnight.
take out of freezer in the morning and immediately insert into the charger, or in the case of laptop batteries, plug it in and turn it on while charging.

I do this with mobile phone, AA and AAA, video camera, garden and power tools, really, any rechargeable battery.

I won't bore you with the technical details, but, if you understand physics, you can probably figure out what's happening

[Bigaldoc]

Thanks, Claude. I did NOT know this technique. The problem is: complete discharge!

In the case of a camera or mobile phone, the discharging battery gets the device to the point it will no longer turn on; OR, it will turn on, give a brief warning and turn itself back off.

Do you suppose that's sufficiently discharged for the freezer routine?

[Claude]

Yep, you're ready to freeze

[Bigaldoc]

Didn't see your comment until the wee hours of this morning, but I plunked FOUR in the freezer at 8 am and wrote myself a reminder note (here on my desk) to REMOVE 'em about 5 pm. I guess that should suffice as "overnight."

I'm also gonna plug my charger in here at the computer desk so I won't forget to take the batteries OUT when the lights turn green.

[viking33]

Another little battery tip.
Whenever I replace a battery, rechargeable or standard alkaline, I put one of those 3/4" diameter Avery label DOTS on the battery and note the date of replacement.
When they finally do run down, it sometimes amazes me when looking at the date, but I always put a voltmeter on them to test them. Usually when there is a group of say, three batteries in a device, it is most times only ONE that that is the bad actor, not the entire group. So being the cheapo that I am, replacing one does the trick. Good to go, particularly when it is a non mission-critical device.

[Bigaldoc]

The date thing is a good tip. Chris suggested it too. Funny thing is that I'm already a fanatic about dating the user doc or manual that comes with anything - computer drive, vacuum cleaner, etc.

But I've not thought of doing it with batteries, except in my cell phone 'cause it's larger and rectangular. I do believe I'll start though.

I've got an el-cheapo voltmeter around here someplace. I think I better hunt for it... Thanks Bob!

[Bigaldoc]

... <snip> ...I do this with ... power tools ...

I forgot to tease ya last night, Claude.

I hope you don't have a rechargeable CHAIN SAW ... unless of course you've got a BIG freezer!!!