Buying the correct battery energiser for your electric fence need not be complicated. Electric fences are typically run by energisers, which pull power from batteries. These batteries are often 9 volts or 12 volts. You could get sufficient power from a D-cell or 6 volt battery if you have a smaller fence.
Here at The Grit, we have all kinds of battery energisers for your electric fence. Our best selling 12 volt battery energiser with an optional solar panel from Thunderbird is easy to set up. It comes complete with leads for the earth and the fence itself. Just instal the energiser, and it will be up and running in just a few seconds.
Don't ever use a 12-volt car battery to help you run your electric fence. Car batteries offer short bursts of high power and will then move to a low power mode. This structure is not recommended for electric fences, which should always have continuous, stable power.
How big should the energiser be? As a rule of thumb, you should pick an energiser designed for a larger fence. It should cover a longer distance so that you can have more room for growth.