Put yourself in charge of battery fact or fiction

Do rechargeable batteries always save you money, and can you really get expensive button cells from inside a larger battery?

For something so ordinary, batteries are surrounded by an awful lot of folk wisdom — or maybe superstition.

Because it's hard to save money when you don't know what's what, The Frugalista turned to two experts to separate battery fact from fiction: Tony Mazzola, a chemical engineer who has been making batteries with Energizer for 28 years, and Brian Bessey, co-owner of five HP tx2000 Battery Plus stores.

Fact or fiction: Rechargeable batteries save hundreds of dollars per cell.

Answer: Mostly fact. Say you buy a set of four rechargeable AA batteries for $20 and four alkaline AAs for $3. The alkaline batteries may last a little longer than the first charge of your rechargeable laptop batteries, but then you get to use the rechargeables 500 to 1,000 more times. They should pay for themselves long before their life is over.

But here's the twist: Rechargeables may not save money if you put them in devices you don't use often. That's because they have a shelf life of only three to five years, compared with seven years for an alkaline, Mazzola said.

If you put the rechargeable batteries in a clock, which doesn't draw much power, or a toy that doesn't get everyday use, you might need to recharge them only once or twice a year. Then, four years later the rechargeable batteries are dead, and you've only gotten a handful of charges out of them, while the alkaline HP Probook 4510s Battery may be still chugging. You just spent $17 extra for a set of batteries that didn't last as long as the one-time-use cells.
On the flip side, my old audiobook player took AAAs that I recharged nearly every day, saving me hundreds of dollars over two years.

Fact or fiction: You can take apart big batteries and find more expensive little batteries inside.

Answer: Mostly fiction. There are "battery hacks" videos online showing a consumer HP dv6000 Battery cut open to reveal lots of smaller batteries, known as button cells. The maker of one video claimed the trick saved him $40 compared with buying the button cells individually.

Some of these videos are hoaxes, like one in which a Dell d620 Battery for a lantern is opened to reveal 30 AAs inside. But if you open a 12-volt A23 battery, the kind that might power your garage door opener, you will find eight button cells inside. I know because, in The Frugalista Labs (aka my husband's workbench), I used wire cutters to take the casing off a chubby little A23.

At first I was excited to see eight button batteries inside. But when I gathered up toys, thermometers and other devices around the house that took button batteries, I was disappointed to see that the ones inside the A23 didn't fit in any of them.

Bessey said he and his staff opened up a 12-volt battery and found the same cells I did.

"That size Acer 5520 Battery is not used in very many applications," he said.
So unless you have a watch or some other device that you know takes a 1.5-volt 394 battery, this trick is a dud. It's not unusual for batteries to be full of smaller cells, Mazzola said, but the cells are not usually in a form that's useful to the consumer. Even if they turn out to be the batteries you need, they may lack contacts or insulation, without which they could damage your device.

Fact or fiction: You should completely drain a battery before recharging, or it will forget how to fully charge.

Answer: Depends whom you ask.

Bessey said that if you plug in your cell phone or laptop battery before it's empty, "the fuel gauge in the battery will start getting a false reading. Every once in a while, draining it all the way down and letting it charge back up will reset that." A Batteries Plus fact sheet backs him up.

But Mazzola disagreed. "The advances made today in batteries preclude the memory effect from being a worry to anyone." The memory effect dates to the 1960s, he said.

As Mazzola told me, "Some old myths are hard to break."

Here's one old battery habit I will be breaking: storing batteries in the freezer. This is potentially harmful, Mazzola said, because freezer temperatures could damage the battery's contacts by causing condensation, then corrosion.