Energizer Rechargeable USB Charger

Many wireless mouse and keyboard users have long since twigged to the benefit of rechargeable batteries – they’re much cheaper than disposable batteries, not to mention more environmentally friendly. Remembering to keep a set of cells topped up in a mains-powered charger is something else though, which is why this latest gadget from Energizer is so handy -- it’s a charger that’s powered by a PC’s USB port.

Both small and light enough to slip into a pocket, the Energizer USB charger can charge two AAA or AA batteries at once, or one 9V battery. The different cell sizes are catered for by one set of terminals being on a two-position plastic block that hinges back when a larger cell needs to be inserted. This clever arrangement does have one small problem – on our model, one AAA battery kept pinging out from between the sprung terminals.

The captive USB cable wraps around the charger’s base when not in use, but the short captive cable needs to be pulled extremely taught for the USB plug to clip into the slot on the charger’s underside. Still, it’s an extremely neat arrangement – take note, Buffalo!

Charging a pair of batteries simply involves plugging the Energizer USB charger into a USB port and a green LED blinks during charging. The charger's electronics prevent overcharging too, so you can leave a set of batteries in place and trickle-charging until you need them. Which is just as well -- at seven hours to recharge the supplied pair of 900mAh AAA batteries and eight hours for two 2500mAh AA cells, this isn't a charger to reach for if you're in a hurry.

If your rechargeable battery requirements don’t go beyond need an occasional fresh pair to replenish your mouse, then this crushingly slow recharge isn’t much of a problem, but it severely limits the Energizer USB charger’s usefulness. Its compact size makes it ideal for slipping into a laptop bag, but a mains charger makes far more sense for most circumstances. Energizer makes one that costs just £1 more and can charge four AA cells in an hour, so even if you forget to charge batteries beforehand, you won’t have long to wait until they’re ready.