The INQUIRER guide to....

ABOUT A YEAR AGO, I bought several NiMH Energizer rechargeable batteries at one of the Amazon Z-shops. I've been quite pleased with them and would like to share some of what I have learned by both research and practical experience (a.k.a educational blasphemy).

There are several sizes of batteries that I purchased: AAA, AA, D, and 9V. I used the AAA batteries in my Palm III and Maglight Pen light (single AAA), the AA batteries in my Sanyo Walkman, the D batteries in my 4 "D" Maglight flashlight.

Here is a profile of battery chemistry attributes:

NiCd (Nickel Cadmium)
Lasts about ¼ as long as alkaline. They recharge about 500 times. They develop a memory if not discharged most of the way before recharging, which means they will lose their ability to charge to full capacity. These batteries were obsoleted for use in consumer electronics by NiMH batteries.

NiMH (Nickel Metal Hydride)
Lasts about ½ as long as alkaline. These batteries have no memory and recharge up to 1000 times. However, this battery chemistry will dissipate ~30% of their charge per month, which makes them less practical for a remote control or any device in which batteries will last for years. The cost for "AA" NiMhis $3-$5 each. "AAA" is $2.25 to 4, "C" is about $6, and "D" is also $6. Compared to buying regular batteries, the break even is about five charges. This is the most environmental and most economical battery solution. These are especially good for digital cameras, which eat batteries alive. Less practical but still worth it was the "D" size in my Maglight, which I have to charge at least every two months, regardless of use. If lifetime use were 250 charges, which is about 2 cents per use - economy and ecology finally start synchronizing.

Regular Batteries
Lasts about ½ as long as alkaline. They cost from 40 cents to $1.

Alkaline Batteries
Usually I buy the copper-top or the musically-inclined bunny versions. The cost is about 80 cents to $1.50.

Thanks in part to good charging technology and battery chemistry, NiMH cannot be overcharged. When the NiMH battery reaches full charge, the charger goes into a "trickle" mode that prevents overcharging. The Energizer NiMh/NiCd charger was about $20.

You might have to hunt a little for them, as it is not as profitable for outlets to sell them versus disposable batteries. Since they are still a little hard to find, try a local camera shop or online at Amazon.com (search for "AA NiMH") or at batteries.com.

Conclusion
NiMH technology overcomes the memory and capacity weaknesses of NiCd batteries, which makes NiMH batteries practical for devices whose batteries need replacing often.

All together, I spent about $80, which I considered a great investment. This saves me about $20 a year in batteries; yielding about a 25% return on my battery investment a year. Also, I've always thought throwing batteries away was a needless waste. Finally, an ecologically superior solution that is economically beneficial.

Phil Trent
July 7, 2001