Boat battery for reliable power on board
A boat battery powers everything on board: from the starter motor and navigation lights to fridges, depth finders and bilge pumps. A standard starter battery provides a short, powerful current peak for starting the engine but is not suitable for sustained continuous discharge. A deep cycle marine battery is specifically built for regular deep discharge and full recharging. Find batteries from 40 to 240 Ah in standard lead-acid, deep cycle and AGM versions.
Which battery type do I need?
| Type | Use | Capacity |
|---|---|---|
| Standard 12V lead-acid | Engine starting, basic lighting | 40-95 Ah |
| Deep Cycle | Sustained load: refrigeration, navigation, house bank | 75-240 Ah |
| AGM Dual Purpose | Starting and house bank, maintenance-free, vibration-resistant | 60-105 Ah |
Rule of thumb: add up total current draw of your devices and multiply by hours at anchor. That figure in Ah is your minimum capacity. Add at least 20% buffer for longer range. Also check outboard motor accessories.
AGM or standard lead-acid?
AGM batteries (Absorbent Glass Mat) have the electrolyte bound in fibreglass matting. They can be mounted on their side, won't leak, have lower self-discharge and charge faster. Ideal for boats with movement. Standard lead-acid is cheaper and perfectly fine for fixed installations in engine bays that don't tilt.
Frequently asked questions about boat batteries
How do I charge a marine battery?
Always use a charger suitable for your battery type. A standard lead-acid charger is not suitable for AGM due to different charge voltage. Connect red to positive, black to negative. Use an automatic trickle charger when the boat stands idle for long periods to maintain voltage without overcharging.
How long does a marine battery last?
A well-maintained deep cycle battery typically lasts 3 to 7 years depending on charge cycles and depth of discharge. Never discharge below 50% as deep discharge significantly shortens battery life. Standard lead-acid batteries last 3 to 5 years with regular starting use. Store fully charged in a dry, frost-free place during winter lay-up.
Can I connect two batteries in parallel?
Two identical batteries of the same type, capacity and age can be wired in parallel to double total capacity. Use equal-length cables for even current distribution. Never combine a new with an old battery or batteries of different capacities. With a starter and house bank setup use a battery isolator or ACR relay. See marine electrics for switches and isolators.
Which battery suits an electric outboard?
Electric outboards place higher demands on batteries than combustion engines. Always check motor specifications for the required battery type and voltage. Lithium-ion batteries are often matched to a specific motor model via a proprietary BMS. AGM dual purpose batteries suit lower-power electric auxiliary motors. Consult the motor manual for correct connection values and capacity recommendations.
In stock? Order before 17:00 and it ships the same day. Otherwise, as soon as possible. Not sure which product fits your boat? Our specialists in Joure are happy to help.
