The Gallagher B40 is the most energy-efficient battery energizer, suitable for fences up to 6 km. The B40 can also be used with solar energy as it comes with a solar panel. The energizer can be powered by solar during the day and by battery at night.
The Gallagher M5000i energiser is the latest and most powerful (freely available) Gallagher I Series Energiser. The capacity of this intelligent powerhouse is enough for fences with a length of up to 100 km!