One Way to Recharge Alkaline Batteries

It says it right on the side of every alkaline battery – do not attempt to recharge. By which of course the manufacturer means don’t try to force electrons back into the cell. But [Cody] figured he could work around that safety warning chemically, by replacing the guts of an alkaline dry cell.

The batteries in question were certainly old, gnarly looking, and pretty dead – [Cody] barely got a reading on his multimeter. As you can see after the break, he cleaned off the exterior corrosion and did a quick teardown of the dry cells, removing the remains of the zinc anode, now in the form of zinc oxide paste looking very much like what you’d slather on your nose before a day at the beach. He filled the resulting cavity with a putty of zinc dust, freshened up the electrolyte charge with a squirt of 20% potassium hydroxide, sealed up the cell with a little silicone caulking, and put the recycled cell to the test. Result: 1.27 volts. Not too shabby.

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Testing 30 brands of batteries

Batteries come packaged in bright blister packs emblazoned with vague guarantees such as “45% more pictures” and “five times longer lasting.” During his internship at BitBox this summer, [Thomas] decided to put those statements to the test. He tested thirty brands of batteries on a homebrew rig to find the batteries with the most power and the most bang for your buck.

The hardware [Thomas] used an STM32 microcontroller to perform two different tests: a high drain and a low drain condition. For the high drain, 1000 mA were sucked out of the batteries until the voltage reached 0.8 V. For the low drain, 200 mA were used. Data including milliwatt-hours, milliamp-hours, joules, voltage, current, power, and effective load resistance were all logged for both conditions for all 30 batteries.

Generalizing the results for both low and high drain conditions, lithium batteries were better than alkaline, which were both better than zinc AA cells. Perhaps unsurprisingly, batteries marketed as ‘long life’ and ‘extended power’ were the worst batteries for the money, but a brand-name battery – the Kodak Xtralife cells – were actually the best value for the money.