Using Rechargeables – Final Thoughts

In recent posts I’ve been talking about using rechargeable batteries for the good of the environment and one’s budget. To conclude, I’d like to outline a few instances when rechargeables should not be used, and add a few observations that might be helpful.

I’ve touched before on the topic of electronic products that specify a need for alkaline batteries, or explicitly state that rechargeable batteries should not be used. This applies especially to the smoke and carbon monoxide detectors in your home. Most of these use 9 volt batteries. While you can get rechargeable batteries of this type, it’s probably best to stick with alkalines. These detectors are life insurance, and should be operated strictly as designed.

Speaking of insurance, if you have fire insurance, make sure these detectors are operated strictly as specified. An insurance inspector might disallow a claim should it be revealed that one had “the wrong kind of battery” in one’s smoke detector. Besides, since rechargeables do run down sooner than alkalines (they have that luxury, since they can be brought back to full charge again and again) one would have to change them more often, which is inconvenient.

Similarly, one should probably use alkalines to power any electronic device under warranty, at least until that term expires. While a rechargeable battery may not harm the device, it might void a warranty claim on a technicality.

These are about the only times a rechargeable battery shouldn’t take the place of a one-use alkaline battery.

As is true of any battery, rechargeables work best around 70° F, with reduced capacity at lower temperatures. Keep them warm for full use. If it’s cold, and your electronic device seems to have low power, pop out the batteries and warm them in your pocket for a bit. This also works with alkalines. I don’t know if it’s more noticeable in rechargeables or not.

To maximize the charge use of a rechargeable battery, I recommend taking advantage of the trickle feature of most chargers. Commonly, a charger shows a red light as the battery fills up, then turns green when it reaches full charge. At that point, most chargers scale back to a “trickle charge,” which tops the battery off at a much lower rate.

I’ve done my best not to describe how batteries work. To be honest, I barely know myself, and it’s tedious to paraphrase what better-informed people have written more lucidly elsewhere. However, in brief, a battery generally charges quickly up to almost full, then needs a long charge at a much lower rate—that trickle charge—to 100%. This is why many off-the-grid power producers with mixed systems charge their batteries up with their wind chargers, then use solar power to “top off” the battery bank. Likewise, allowing your rechargeable flashlight batteries a couple of hours of trickle charge after you get the green light often gives you more work time than if you put them to work as soon as the green light comes on. Just make sure your charger cuts back the power! Some of the cheaper ones will continue at full charge, which can damage your batteries. Your unit’s instructions will be very explicit on this point.

One final thing to remember is that many rechargeable batteries take a bit of time to “break in” before they reach their maximum power potential. In other words, at first they’ll provide shorter run times between charges, until they’ve cycled through several times.

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Mark Zeiger is a regular contributor to Self Reliance Works. He and his family homestead off the grid in Southeast Alaska, so, as you might imagine, much of their power comes from rechargeable batteries. Learn more about their life through their photos and blog at AKZeigers.com.