My family of four goes through AA's like peanuts. In February, I bought the kids RayOvac rechargeable AA's and a couple of rechargers. It has been a real money saver.
Recently, I discovered the charger full of conventional [alkaline] AA's, and, as I have been conditioned to do, cordoned the area off and declared an emergency. My son informed me that he had been resuscitating conventional batteries as well, and they work "great."
Intrigued, i tried it. The alkalines indeed took a charge, but it was certainly not as powerful. I keep them as spares.
So--have I uncovered a great conspiracy, or am I risking a disaster-? Will this damage a recharger-?
I apologize if this may have been covered before here.
Before the days of alkaline batteries it used to be possible to recharge single-use batteries, but the designers of such rechargers always warned that recharging might lead to leaking with consequent damage to the devices in which they were installed.
But I've always found Rayovac to be the most leak-prone batteries anyway, so . . .
I don't see any problem with doing this but new AA batteries aren't that expensive when bought from web based suppliers. I usually by 144 at a time and it doesn't break the bank.
No conspiracy. The chemistry is simply not reversible. What is happening, if I may analogize, is that you are scraping down the sides of an near empty bowl to get another spoonful of charge.
Rapid discharge causes unbalanced localized depletion of the chemistry and high internal resistance and therefore low voltage under load. Just letting them sit around for days or weeks will migrate the electrolyte somewhat and restore some charge to being available. This migration is accelerated by heating, and that's what the charger is doing, not charging per se. But you'd get the same "charge" just letting them sit, or warming them by other means.
Try utterly killing an alkaline with a slow discharge, say a 150 ohm resistor load for a week or so. Then try your "charging" and see what you get. Nuttin.
Alkaline mfrs continuously play with trivial variations of their cell geometry and formulas to make cells "longer lasting" than the competition. All this is is changing the performance to be optimized for large vs small loads. Brand X lasts longer than Y in a radio (small load), but Y beats X in motorized toys (large load).
That's why you *never* see actual performance numbers (discharge curves for various loads) on retail batteries. You just see pink bunnies that go and go, and vague suggestions of new formulas in a business that hasn't changed technically in decades. In fact, they're all about the same if fairly compared, otherwise the better ones would boast actual numbers.
So Richard, are you telling us that Rayovac, Panasonic and the other manufacturers who make rechargable alkaline batteries have been lying to us?
I've used these types of batteries in the past, and they sure seem like they "recharged" pretty fully lots of times for me. I lost track of them long before they "wore out".
There may be some subtle difference between the "regular" and the "rechargeable" alkalines so that they work better but the "chemistry" is the same.
For a short time a few years back you could buy chargers for alkalines. The battery makers countered with their own chargers and "special" batteries. They accomplished their mission which was to get the other chargers off the market. Once that was done, they went back to making one time use only batteries (but they can still be recharged.)
The NiMH cells are VERY good, however. I must have a couple dozen each of AA and AAA cells. (The "C" size doesn't seem to have any more capacity than the "AA" size.)
The concern I have heard is they will leak, I have alkaline and nicad chargers and have not been happy with the amount of recharge, which seems to be 10-25%. I would charge them then test them in heavy use items. I stopped charging alkalines. Maybe my charger was ng if others have different luck Someone should do a test , draw down new batteries , time it ,then test recharged alkalines.
There are primary (one use) adn secondary (rechargable) alkalines. Recharging the primary cells makes them much, much more likely to leak. This from personal experience.
My local BJ's wholesale club has AA's pack of 48 for $11.99 which works about 25 cents a battery.
I think you did good to be careful with the charger full of alkalines. Might want to buy some more NiMH batteries, and then you can keep some charged ones around. Couple in the charger, and a couple in the device.
Some folks sell them on Ebay, or you can find them on a Google search, for "AA NiMH 2300".
There is a charger called a Battery Manager Ultra. I have one of them, they used to sell them through Johnson Smith. Supposed to recharge normal alkalines, as well as renewal, NiCd, NiMH, and so on. If they aren't totally dead, they can be recharged. But some will leak.
If you charge alkalines when they are still fresh, sometimes you can top them off. But after they are drained, they won't recharge (or they will leak if you try). So, your son mighta tripped on something. But I wouldn't encourage it. Too likely to leak and ruin your device.
Only if it's a cheap charger. If you have a proper, smart charger the batteries can stay in them forever. They are charged to full and then the charger sets back to a sustain level and keeps them topped up.
In my experience, rechargable alkaline are not worth the trouble or expense. NiMH are better for most applications I use.
Here's something to keep in mind. Alkaline batteries are 1.5 volts. Nicad rechargable batteries are 1.2 volts. A device designed for 4 alkaline batteries uses a total of 6 volts, but when you substitute rechargable nicads you only have 5.2 volts available. Most toys and general purpose devices will not see a noticeable difference, but some sensitive electronics will not work with the lesser voltage. I have a camera flash unit that refuses to work with nicads for that very reason.
I think NiMH are about 1.4. They also come in higher maHhrs [2400 at least] - and don't have the 'memory' problems of NiCads. [The only 'down' side is that they die all at once. On my camera, when the battery warning light comes on, you're effectively 'done'.]
I've been using them for all my AA needs for 5-6 years. I still have a few of my original 800 maHr batteries kicking around. They have powered various flashes, cameras, cd players, flashlights and toys & have done it as well or better than Duracells.
When I started using them they were a bit more expensive than NiCads, but worth the difference. I think they're about the same now. I buy mine at
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. [I have two of his chargers featured on this page-
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and I've used the car adapter feature a couple times ] Jim
A few devices do have problems due to this. They also waste a great deal of an Alkaline battery's discharge cycle. (If you have devices like this, don't throw the Alkalines away when they no longer power them, but try reusing them in a less power-hungry device.) But all the devices I've tried rechargeable in have no problems. From what I understand, even though Alkalines start at a higher voltage, they begin dropping in voltage as soon as they're used. They can give less than 1.25 volts over a large portion of their life. Rechargeables remain more constant.
I've played around with a voltmeter and my NiMHs and found out that when fully charged, they really give about 1.35-1.4 volts each. They gradually drop until they reach about 1.15-1.2. Then, depending on the device, they will die very quickly at about that point. Alkaline batteries have a much larger (and more gradual) voltage range over their life. So low battery indicators don't tend to work well with rechargeables, because most of them are calibrated for alkaline batteries only.
Even though this might not be the best method, I have had no problems so far using a voltmeter to estimate the remaining capacity in a NiMH battery based on the voltage reading, though.
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