# Truck battery: how to choose one and where to fit it in Málaga > Blog article — Málaga Baterías · Updated 2026-11-01 _How to choose your truck battery: 12 V/24 V in series, Ah and cold cranking, Varta ProMotive SLI, EFB or AGM by use. Fitted with no appointment in Málaga._ You don’t choose a truck battery the way you choose a car battery. It sits in a 24 V system, has to crank large-displacement engines and, very often, has to power a cab that doubles as a bedroom at night. In this guide we explain, from the counter of our shop in Málaga, which figures to check, which Varta ProMotive range suits each type of work and why most of the failures we see can be avoided by choosing well. Quick answer: almost all trucks run on 24 V with two identical 12 V batteries connected in series. Choose the size, capacity (Ah) and cold cranking current (A EN) that the manufacturer specifies; choose the technology by use: SLI for a truck with few electrical loads, EFB for delivery work with lots of stops and AGM for long haul with a cab, fridge and heater. Always replace both at the same time. In Málaga we fit them at the shop, no appointment needed. 12 V and 24 V: how the battery works in a truck Most trucks, coaches and commercial vehicles run on 24 V. Since starter batteries are 12 V, two identical units are fitted in series: the positive of one is linked to the negative of the other, so the voltage adds up while the capacity stays that of a single battery. - Two batteries, one team. If one weakens, the other has to work harder and starting suffers even if the second one is healthy. - Beware of 12 V “tapped” from one battery. Wiring the fridge, radio or a charger to just one of the two drains it more than the other and unbalances them. The right way is a 24-to-12 V converter. - Vans and some light vehicles run on 12 V with a single battery. If that’s your case, the choice is closer to that of a car. Ah, cold cranking and size: the three figures that matter Before talking about brands or technologies, three figures have to match what your truck requires: - Capacity (Ah). This is the energy the battery stores. In trucks, the most common sizes range from about 140 to 225 Ah. More capacity gives headroom for the cab, but only if it fits the tray and the alternator can charge it. - Cold cranking (CCA, in Europe “A EN”). This is the current it delivers in the first cranking burst in the cold. A big diesel engine needs every bit of it on winter mornings. - Size, terminals and polarity. The case has to fit the tray, the terminals have to sit in the right place and the hold-down has to clamp firmly: a battery that rattles with vibration lasts far less. SLI, EFB or AGM: which Varta ProMotive for your work Varta, for whom we are an Official Distributor, has three ranges for heavy vehicles. The choice depends less on the truck and more on how you use it: How the truck is used What wears the battery Recommended range Regular use, routes without many stops, few electrical loads Mainly starting and vibration Varta ProMotive SLI Delivery work with lots of stops (industrial estates, city, Costa del Sol) Constant restarts and little charging time between stops Varta ProMotive EFB Long haul with a cab: fridge, parking heater, lights and chargers all night Deep discharges with the engine off, night after night Varta ProMotive AGM Construction, tipper or crane Heavy vibration, dust, short trips and hydraulic equipment EFB, or AGM if there is also heavy use with the engine off With hard use, fitting an SLI to save money usually ends up costing more: it gets deeply discharged, degrades and causes trouble again before long. We also explain the differences between the technologies in AGM vs EFB . Which battery does your truck take? Come to the shop, no appointment needed, or send us the part number or registration on WhatsApp and we’ll tell you the right ProMotive. Call 952 31 01 18 WhatsApp Why both batteries are always replaced together In series, both batteries receive the same charging current. If one is new and the other is years old, the old one fills up sooner and empties sooner: the alternator ends up overcharging one while the other falls short. The result is that the old battery drags the new one down and, before long, you have a truck that starts badly again. That’s why, on a 24 V truck, we always replace both together, with the same part number, from the same range and with the same manufacturing date. It’s the only way for them to work in balance and for a truck battery replacement to last as long as it should. Signs that your truck battery is failing - The starter motor turns slowly, especially on the first start of the day. - After a night with the fridge or heater on, the truck won’t start or needs jump leads. - Low-voltage warnings appear, the dashboard flickers when starting or some equipment resets. - With the engine off and after a few hours at rest, each battery reads well below 12.6 V (the pair, below about 25 V). Measure them separately: that shows whether one is worse than the other. - The case is swollen, there are leaks or the terminals corrode again and again. - You need jump leads or a charger more and more often. Before blaming the battery, it’s worth ruling out an alternator that isn’t charging properly or a load that stays switched on. If the truck has gone flat, see what to do in flat battery . Mountain-pass cold and summer heat: the Andalusian climate matters too Winter: early starts and mountain passes Málaga is known for its mild climate, but many trucks leave before dawn for inland Andalusia and cross passes such as Las Pedrizas on the way to Antequera. In the cold, the battery delivers less current and thick oil makes the starter work harder. A battery with barely enough cold cranking, or one that’s already tired, usually gives its first warning on those mornings. Summer: a cab in the sun and the fridge on all night The heat of an Andalusian summer is even worse for the battery, although you don’t notice it at the time: it speeds up internal wear and water loss. Add a battery compartment that heats up and nights with the fridge and cab air conditioning running, and the battery wears out sooner. … ## 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/truck-battery-how-to-choose-malaga)