Recharging 'standard' alkaline batteries?

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The latest Northern Hydraulics catalog lists a battery recharger that claims to "safely recharge ordinary AAA, AA, C & D alkaline and NiCad batteries one to 4 at a time ... Won't overcharge" (item # 160636-C131 $19.95).

Does anyone have any experience with a product like this? I've always thought throwing away 'standard' alkalines was a waste and that they could be easily recharged. So how well does this appraoch work? Thanks in advance.

-- Arnie Rimmer (Arnie_Rimmer@usa.net), January 02, 1999

Answers

Be careful. One of my Buds at work smoked his basement with one of these. The insurance folks cut him a lot of slack but he still had a smelly basement.The caveat is, don't put them on a charger without being able to watch them until the full charge is obtained.

-- nine (nine_fingers@hotmail.com), January 02, 1999.

Arnie:

Ordinary alkaline cells aren't designed to be recharged. All that the alkaline "rechargers" do is buy a =little= more use of a nearly-dead cell. Here's what happens:

As you use a cell, especially in more demanding service (heavy-duty use) microscopic bubbles begin to form around the center electrode internal in the cell. This electrode is the one that's connected to the positive cell contact (the "bump" on top). While bubbles also form around the negative contact .. (the negative contact is the entire cell can itself) .. the vastly greater surface area means the bubbles don't seriously impair cell function. Internally within the cell, the positive contact is a small rod with considerably less surface area by comparison. As the cell is used, more and more of these tiny bubbles form in the electrolyte paste around the rod, which in turn slowly begin to impede the flow of electricity, thus causing the flashlight to grow gradually dimmer, motors to slow down, etc... This formation of bubbles takes place near the end of the cell life, after most of the internal chemicals are used up.

That having been said .. what the "chargers" accomplish is simply to break up the little bubbles around the center electrode, thereby temporarily reducing the internal resistance of the cell and giving the appearance of having "recharged" it. The problem is .. the chemical reaction that actually generates the electricity is cannot be reversed in a conventional alkaline (or carbon-zinc) cell. That would be tantamount to trying to un-bake a cake. The little bubbles rapidly reappear and the cell goes dead very quickly.

Summary: If you want to recharge cells, get rechargable cells. Ni-cads are the most common. Use them until they show signs of discharge .. then recharge them fully. Over a period of time (usually months of regular use), ni-cads tend to develop a "memory" of how they are used .. and abused. If you use them lightly, they become light-duty cells. If you use them within their ratings, discharging them almost completely until the device in use *just* begins to slow down, dim down (etc.), and then recharge them completely, they will give you much longer service. Finally, if your budget can take the hit, some of the newer (albeit expensive) rechargable cells such as those found in laptop computers don't suffer from the memory hassles and store more energy per cell than do conventional ni-cads.

As a final note .. I believe it was Ray-O-Vac that came out with a "rechargable" alkaline. While they *do* re-charge, they never get back to the 100% point. The first recharge regains only about 97% of maximum charge... the second regains only about 97% of the first .. and so on. They have a very limited number of cycles before they become useless. If you want/need rechargeable cells, get ones that are designed to be recharged. Get a solar charger and put it in a sunny window .. "just in case" .. and have some alkaline cells on hand too .. stored cool, they have a shelf-life of several years.

Hope this helps.

-- Dan (DanTCC@Yahoo.com), January 02, 1999.


Thanks for the help. After hearing this, I'll stick with the NiCads -- I've already bought a few of them and a couple of the solar powered rechargers. The NiCads are significantly more expensive (initial cost) but it sounds like they'll be safer and longer lasting (more re-charges of the life of the cell).

-- Arnie Rimmer (Arnie_Rimmer@usa.net), January 02, 1999.

And DO NOT ever put your rechargeable alkalines in the NiCd recharger - nor the NiCd's in a recharger built for rechargeable Alkalines.

The recharge amp rates are very different - so the rechargeable alkalines will quickly overheat, burst the cells, ruin the recharger, melt the plastic, and put a acid hole in whatever the recharger is resting on.

Been there, been done to that, ....

ONLY NICD in NICD, ONLY Alkalines in a Alkaline recharger.

Radio Shack has a NiCd D, C, AA, AAA, 9 V, (Where did B ever go ?) recharger that will also "discharge" the battery first to keep it fully recharged.

-- Robert A. Cook, P.E. (Kennesaw GA) (cook.r@csaatl.com), January 04, 1999.


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