Most battery manufacturers only recommend using own-brand rechargers – and you can usually buy the charger and your AAA cells in a kit. AA battery chargers will also work for AAA batteries – as they are the same length between contacts. Independently manufactured rechargers should be ok but it’s best to avoid very ‘fast chargers’, as these can shorten the lifespan of the battery and can cause problems from the batteries overheating and even leaking. Overcharging can damage or destroy a battery.