12VLeisure Batteries

A car battery is designed to deliver a short, high burst of current to start an engine, then gets topped straight back up by the alternator. A leisure battery is built for deep-cycle use — steady, continuous discharge over hours or days, followed by a slower recharge. Using a car battery on an energiser will shorten its life considerably, as it isn't designed to be run down repeatedly.

This depends on the energiser's power draw and how long you need it to run between charges. Check the output joules and current draw listed on your energiser and match it against the battery's amp-hour (Ah) rating — as a rule of thumb, a higher Ah battery will run your fence for longer before needing a recharge. If you're running a large fence line continuously in a remote location, it's worth sizing up rather than cutting it fine.

Run time depends on the battery's Ah capacity and your energiser's daily current draw, so there's no single answer. As a guide, a low-draw energiser on a fully charged battery can run for several weeks, while a higher-output unit on a smaller battery may need recharging within days. Pairing your battery with a small solar panel is a common way to keep it topped up in remote spots without regular site visits.

Leisure batteries themselves aren't fully weatherproof, so they should always be housed in a proper battery box or energiser cabinet when used outdoors. This keeps rain and damp off the terminals, reduces corrosion, and protects against accidental knocks in field conditions. Standing the battery off wet ground and keeping terminal connections clean will also help it last longer.

A tell-tale sign is the fence energiser struggling to hold voltage even after a full charge, or the battery discharging much faster than it used to. Physical signs like swelling, leaking, or corroded terminals mean it's time to replace it straight away rather than risk further use. Most deep-cycle leisure batteries will give several years of reliable service if charged correctly and not left fully discharged for long periods.

A dedicated leisure battery charger with a smart or trickle-charge setting is the safest option, as it avoids overcharging and prolongs battery life. Solar panels are widely used with fencing setups in remote fields where mains power isn't practical, keeping the battery topped up continuously. Avoid leaving a battery fully discharged for extended periods, as this can permanently reduce its capacity over time.