9 Volt electric energisers are very popular in Europe and increasing in popularity here in the UK. The advantage of this type of energiser is that you do not need to remember to recharge a heavy 12 volt battery. 9 volt batteries are typically lighter and often fit inside the energiser itself. 9 volt batteries cannot be recharged and are replaced approximately every 3 to 9 months, depending on the strength of battery you buy and the condition of your electric fence. If you are forgetful, or don't fancy the idea of lugging a heavy 12 volt battery in for recharging, this could be the right type of electric fence energiser for you!