Caravan Power Package with a Battery to Battery Charger in a Heavy Duty Specification

Power that will run a mover: a DC to DC charger that will charge the leisure battery properly from a modern smart alternator, which a simple split charge relay will not.

Towing is the one thing you can buy for a car where the wrong part is not merely disappointing. Every towbar listing here states the type approval number, the D value, the maximum noseweight and whether the bumper has to be cut, because those four facts decide whether a bar is legal on your vehicle and whether it will pull what you want to pull. Every electrical listing says plainly whether it is a dedicated loom or a universal one with a bypass relay, and what each will and will not do. We would rather lose a sale to a cheaper part than sell you one that does not fit.

Specification

• Fits: any 12 volt caravan or motorhome with a battery box we can get to. Send us a photograph of the existing installation and we will tell you what changes
• Approval: the lithium batteries carry UN38.3 transport certification and a BMS with low temperature charge protection, which is the feature that matters in a British winter and the one cheap lithium leaves out
• Rating: sized to the caravan weight and usage chosen above. The mover draw is designed in rather than hoped for. A motor mover draws a great deal of current, typically 80 to 100 amps under load. It will flatten a tired leisure battery in minutes and it will refuse to move a caravan at all on a battery below about 12.2 volts. Any mover bought without also sorting the battery out is half a purchase, which is why the battery is an option on every mover listing here rather than an upsell afterwards.
• D value: not applicable, this is an accessory rather than a load bearing towing part
• Noseweight: a lithium battery weighs about a third of the lead acid it replaces, which changes the noseweight by a few kilograms. If your caravan sits close to its limit, recheck it. Noseweight is the downward load the trailer puts on the ball, and the figure you may use is the lowest of four numbers: the towbar's S value, the vehicle handbook's noseweight limit, the towball's rating and the caravan coupling's rating. Most people know the first and none of the other three, and a combination that is legal on paper is often over the limit on the one that matters.
• Ball height: not applicable
• Electrics: 12 volt, with every cable sized to the load and fused within 300mm of the battery. The cable sizes are on the wiring diagram in the box
• Fitting time: four to eight hours depending on the package and whether solar is included
• Bumper: not applicable
• Materials: uprated for the heavier end of the range: thicker section, a higher D value and a higher noseweight, which matters more than most people realise
• Weight: approximately 44.0 kilograms
• Guarantee: five years on the batteries, three years on the electronics
• Why lithium: a 100Ah lithium gives about 100Ah of usable capacity. A 110Ah lead acid gives about 55Ah before you damage it. That is the real comparison and it is not the one the price tags suggest
• Low temperature: the BMS refuses to charge below zero degrees, which protects the cells. Cheap lithium without that protection dies in its first winter
• Charger: a standard caravan charger will not fully charge lithium and will sit at about 80 per cent forever. A suitable charger is in every package here
• Monitoring: a shunt based monitor, because voltage on a lithium battery is almost flat and tells you nothing about state of charge
• Solar: not included, and easily added later

What arrives

• the battery or batteries
• the charger or DC to DC charger
• the shunt monitor and display
• solar panels and an MPPT controller where included
• cable, fuses, bus bars and terminals, all sized to the load
• a wiring diagram drawn for the package

Fitting

Four to eight hours. The battery cable to a mover is 25 square millimetre and it is fused within 300mm of the positive terminal, and both of those are non negotiable. Fitting is available at our centres and at your address, and on a solar package we would suggest it, because a roof penetration done badly is a damp problem two years later.

Before you order

Almost every motor mover that has stopped working has a battery problem rather than a mover problem. A mover pulls 80 to 100 amps, which a tired lead acid battery simply cannot deliver, and the mover's controller cuts out to protect itself and gets blamed for it. If you are buying a mover, budget for the battery in the same order. If you already have a mover that has become weak, start here rather than at the mover.