OK, before the electronics bods get on to us, we know that if you put two batteries in parallel then they'll try to equalise their potential difference, but what we're talking about is a battery pack designed to charge smaller batteries on the move.
The Recharge4, produced by a company called Exspect, comes in a number of forms and is designed to plug into the charger port of, say, an MP3 player or mobile phone, and replenish its battery. It can perform a recharge of another device up to four times, say the makers, and so the products name seems to make perfect sense.
Recharge4 is itself rechargeable, and has its own charge level indicator so that users know when it's about to run out of juice. It can provide enough current to both charge a device and power it simultaneously, and all this for 360g of Lithium Ion battery.
Quite a handy tool for the mobile businessman or indeed anybody who will be away from a power point for quite a while and may need to keep their portable devices juiced up.
Recharge4 retails at around forty quid, and is available from the likes of Amazon, Comet and HMV.
