The joy with an electric fence mains energiser is that you never have to worry about charging a battery again as the power is always there and constant. And this is the cheapest way to power your fence too. Just connect to the energy source and that’s it. Because of their reliability and efficiency - mains energisers have a greater power resource to draw from - they can be the answer to wayward escape artists and they are also useful in areas where there is predation from any undergrowth.