Verified answer

You have to have the charger. And, it has to be the type of charger that takes the type of rechargeable batteries you have - I don't mean the size, I mean the type. There are two types of rechargeable batteries; both types come in several different sizes. Some chargers have a switch that you can set for whichever type of battery you are charging. DO NOT EVER TRY TO RECHARGE A BATTERY THAT ISN'T RECHARGEABLE.

There are different chargers for different battery types, e.g. nickel-metal hydride (NiMH), nickel-cadmium (NiCd) and lead-acid. Some newer "smart" chargers can tell when a few different types of battery are charged (technically, they compare voltage change over time and when it stops increasing, the battery should be charged).

Since most people online cannot tell what your "device" is (other than those in Religion>Psychic), it would be difficult to know if it has a battery charger built in, but my guess is, not.

Get one charger for a bunch of batteries and you save $$$: recharge dozens to hundreds of times. Don't use 'em once and discard.

If I knew what your "device" is and what kind of batteries you have, I could make an informed recommendation to you. Most cell phones, for example, will charge their batteries in the phone. This is also true with some digital cameras. Beyond that, it is anybodies guess.

Im pretty sure you need a battery charger.