# Lithium batteries on a boat: when they are worth it and when they are not > Blog article — Málaga Baterías · Updated 2026-10-12 _Thinking of moving your boat’s house bank to LiFePO4 lithium? When it beats AGM, when it doesn’t and what to check first. Delivery to Costa del Sol marinas._ Switching the house bank of a sailing yacht or a cruising motorboat to lithium (LiFePO4) can be the best electrical upgrade on board… or money you will never get back. It depends on how you use the boat, not on what is fashionable. At Málaga Baterías we supply lithium and AGM batteries for boats in Málaga and along the Costa del Sol , and here we explain plainly when the switch pays off, when it doesn’t and what needs checking on board before you go ahead. Quick answer: lithium is worth it if you anchor out often , have heavy loads (fridge, autopilot, inverter), charge from solar panels or care about weight . It usually isn’t if you do day trips and return to a berth with shore power, if your consumption is low or if you use the boat only a few weeks a year: there a good AGM bank does the same job for a smaller outlay. And going lithium is more than swapping the battery: the charger, solar controller, alternator and protection all need checking. What changes with LiFePO4 compared with AGM Both technologies work for a house bank. What changes is how much energy you can actually use. - Usable capacity. An AGM battery should not regularly go much below half its capacity if you want it to last. A LiFePO4 battery lets you use most of its rated capacity as a matter of routine. - Weight. For the same rated capacity, a lithium battery weighs around half as much as a lead one, or less. - Cycles. Looked after properly, a LiFePO4 battery withstands several times more charge and discharge cycles than an AGM. - Charging speed. Lead accepts less and less current as it fills and the last stretch is slow. Lithium takes high current almost to the end and makes better use of engine or sun hours. - Stable voltage. On an AGM the voltage drops as it discharges. On lithium it stays almost flat to the end. AGM Lithium (LiFePO4) Usable capacity Around half the rated figure, if you want it to last Most of the rated figure Weight High Roughly half or less, for the same rated capacity Cycle life Limited if discharged deeply Several times more cycles Charging Slow in the final stretch Fast almost to the end Voltage during discharge Drops gradually Stable almost to the end Weeks without reaching full charge Harmful (it sulphates) Tolerates it well Installation Compatible with almost any charger and alternator Charger, alternator and protection must be checked Initial outlay Lower Higher When switching to lithium pays off - You anchor out often. If you spend nights away from the marina, every usable amp-hour counts, and lithium gives you more autonomy in the same space. - You have heavy loads. A compressor fridge, autopilot, instruments, lights and an inverter add up fast. - You charge from solar panels. Lithium takes everything the panels deliver almost until it is full and doesn’t suffer from sitting at half charge for days. We explain it for campervans in leisure battery with a solar panel . - Weight matters. Cruiser-racers, multihulls, planing motorboats or boats with the batteries far from the centre: shedding tens of kilos is welcome. - Intensive use. If you live aboard, make long passages or the boat works in charter, the extra cycles pay for themselves. When it doesn’t pay off - Day trips with shore power at the berth. You leave in the morning, come back in the afternoon and the shore charger tops the battery up. You hardly cycle it: a properly sized AGM bank is more than enough. - Low consumption. If all you have on board is lights, a depth sounder, a radio and little else, you won’t make use of the extra capacity. - A boat used a few weeks a year. Lithium pays for itself by cycling. If the boat spends nearly all year tied up, you are paying for cycles you won’t use. In that case it matters more to look after what you already have: see how to winterise your boat battery . And if on top of that you have to replace the charger and controller and add a DC-DC charger without the use to justify it, a good AGM bank is the better buy. We sell both, so we’ll tell you either way. Lithium or AGM for your boat? We’ll give you a straight answer Tell us what bank you have, your loads and how you charge, and we’ll quote both options. Collect in store or have it delivered to your marina. Call 952 31 01 18 WhatsApp What to check before you switch A lithium battery doesn’t simply go “where the old one was” without looking at anything else. Go through this with your marine electrician. Shore charger and solar controller Both must have a lithium charging profile (LiFePO4) or let you adjust the voltages. A charger designed only for lead may use voltages and stages, such as equalisation, that don’t suit a lithium battery. If yours doesn’t have that profile, it has to be replaced. Alternator A lithium battery accepts so much current that it can keep the alternator working flat out for a long time and overheat it. In addition, if the BMS cuts charging abruptly, the alternator can suffer a voltage spike. The usual solution is a DC-DC charger between the starting circuit and the lithium bank, which limits the current and protects the alternator. BMS, fuses and cable size The BMS is the electronics that monitors the cells and disconnects the battery if voltage, current or temperature go out of range. Check the maximum current it allows, especially if you have an inverter or a windlass. Lithium can deliver very high currents, so you need a suitable fuse close to the battery and cable sized for the real current. The starter battery is still lead The normal approach is to move only the house bank to lithium. The engine still starts from a lead battery, built to deliver the cranking peak. If you’re not sure which one your engine takes, we cover it in the boat and marine battery guide . Safety: why LiFePO4 “Lithium” is not one single thing. LiFePO4 (lithium iron phosphate) is the most stable chemistry in the family and the one used in boats and caravanning for house banks. … ## Buy or change this battery in Málaga Málaga Baterías — official Varta distributor. No appointment needed. Free quote and recycling of your old battery. - **Phone:** [952 31 01 18](tel:+34952310118) - **WhatsApp:** [+34 952 31 01 18](https://wa.me/34952310118) - **Address:** C/ La Orotava, 100, 29006 Málaga - **Directions:** https://maps.google.com/?q=Málaga+Baterías+C/+La+Orotava+100+Málaga ### Areas we cover Málaga city: Centro, Teatinos, El Palo, Pedregalejo, Ciudad Jardín, Cruz de Humilladero, Carretera de Cádiz, Churriana, Campanillas, Puerto de la Torre, Bailén-Miraflores, Palma-Palmilla. Costa del Sol: Torremolinos, Benalmádena, Fuengirola, Mijas, Marbella, Rincón de la Victoria, Vélez-Málaga, Torrox, Nerja, Alhaurín. --- [See the full product page](https://malagabaterias.com/en/blog/lithium-batteries-boat-when-worth-it)