Why Isn't My Caravan Battery Charging? 7 Common Causes

Before you start

You'll need a multimeter. Most charging faults can be found by measuring voltage at a few points. As a rough guide, a resting 12V battery that's been off charge for a while reads about 12.8V when full for AGM, or around 13.3V or more for lithium. While charging, you'd expect to see a higher voltage at the battery.

Check these in order

1. No charging source: make sure the engine is running, the solar panel is in the sun or the mains charger is switched on. Check voltage at the charger's input.
2. Blown fuse or tripped breaker: check every fuse and breaker along the way, in the car, inline, at the battery and in the van.
3. Plug and connection problems: check the Anderson plug and the car-to-van connection for loose, burnt or corroded contacts.
4. DC-DC charger or controller fault: check the status lights and any error codes against the manual, and confirm the ignition or trigger wire is connected if it needs one.
5. Wrong battery settings: set the right battery type (lithium, AGM or gel) on every charger and solar controller.
6. Battery problem: check terminals are tight and clean. An old battery may not hold charge even when it's receiving it.
7. Too much voltage drop: cable that's too thin or too long stops chargers reaching full voltage. This is very common on long car-to-van runs.

How to test with a multimeter

Measure at the battery terminals with everything off to see its resting voltage.
Start the engine (or put the panel in the sun) and measure at the charger's input. No voltage there means the problem is before the charger.
Measure at the charger's output. If the input is fine but the output isn't, look at the charger and its settings.
Measure at the battery while charging. If it's well below the charger's output, you're losing voltage in the cable, fuses or connections between them.

Solar-specific checks

Shade, dust or a poor panel angle can cut output dramatically.
Check the panel lead and plugs for damage.
Make sure the controller is set to the right battery type and isn't showing a fault.
In winter, solar output is much lower, so it may simply not be keeping up with your usage.

When to call an expert

If you've checked everything and still can't find it, or you find melted or burnt wiring, stop using the system and have an auto electrician look at it.