How do I test my caravan battery charger?

In today’s article, we will answer the following question: How do I test my caravan battery charger? We will explain how to do it, step-by-step, but also tell you how to connect and unplug a caravan battery charger. 

How do I test my caravan battery charger?

To test your caravan battery charger, you need just two easy to find devices:

  • A voltmeter and
  • A multimeter. 

The two devices are different in the quantities they measure. The voltmeter measures the electrical voltage in volts between two terminals in a circuit, and the multimeter is more complex than the voltmeter because it measures other quantities in addition to the voltage in volts and the intensity of the electric current in amps. 

As its name suggests, it is a multimeter that measures several quantities that emit signals such as resistance in ohms. The multimeter makes it easier to measure several quantities. The quantities can be measured in different modes such as continuous (AC) or variation (DC). The AC setting is used to check the operation of the charger and in DC mode for the battery.

Connecting the multimeter to the caravan battery charger

The nominal voltage is checked on the indications written on the battery charger. First, the multimeter is started by setting it to the nominal voltage of the charger. For a charging capacity of 22 volts of your charger, you must put the multimeter on 25 volts too. We also turn on the 22-volt charger and turn it on. 

We then connect the negative probe coloured in black of the multimeter to the negative terminal of the charger and also in the same way we connect the positive probe in red of the multimeter to the positive terminal of the battery charger. The charger is now connected to the multimeter and it is possible to start checking the operation of the charger. For this, steps must be taken for verification.

Checking the operation of a caravan battery charger

The measurements should be taken by reading on the multimeter’s display. To check the correct operation of the charger, the charger voltage is read on the multimeter’s screen. To be sure that the charger operates correctly, the multimeter’s screen should read a voltage greater than the nominal voltage written on the charger. 

For example, for a charger rated at 22 volts, the multimeter should indicate a voltage greater than 22 volts or 25 volts or slightly greater than 25 volts when the charger is functioning correctly. You also have to be careful since a charger actually supplies a voltage higher than the nominal voltage to quickly charge a battery. 

When the multimeter displays a voltage much lower than the nominal voltage of the charger, it shows that your charger is damaged and if no voltage is displayed then the charger has failed.

How to measure a caravan battery capacity?

The loads imposed on your battery can be measured from the amount of current used by the various electrical components: the headlights take about 8 to 10 amps, and a heated rear window as well.

Theoretically, a fully charged battery, with no outlet from the generator, should run the starter for about ten minutes, or the headlights for eight hours, and a heated rear window for 12 hours. As the battery nears its full discharge, the lights gradually decrease in power.

There are also causes other than short trips and cold weather that can affect the condition of your battery. Faults are more frequent on cars equipped with a dynamo rather than those with an alternator because the alternator produces more electricity even at low speeds (see How the charging system works).

The answer in all of these cases is frequent testing with a hydrometer (see Checking the battery) to see how much capacity remaining in the battery there is, and using a battery charger to recharge its charge if necessary.

How to connect a caravan battery charger?

Some batteries have a simple cover to mount on the central bin.

  1. If separate cell plugs are installed, remove them for ventilation. Leave a dip to cover, unless the charge rate is high. Attach the positive (+) wire of the charger, usually red in colour, to the positive post of the battery. Attach the negative (-) lead, usually black in colour, to the negative terminal.
  1. Connect the charger to the mains and switch it on. The indicator light or gauge (ammeter) will show that the battery is charging.
  1. The gauge may show a high charge rate at first, but this number gradually drops as the battery charges.
  1. If it were empty, the charge is likely to take some time; check periodically with a hydrometer while continuing to charge.

In the final stages, the bubbles of the cells give off-gas. If one of them starts gassing before the others, the battery is probably faulty and should be checked by a specialist.

How to unplug a caravan battery charger?

After charging, always switch off at the mains and unplug the charger before removing its terminal clips – otherwise, the clips may arouse and ignite the gas which is released during recharging.

Also, make sure that no electrical circuits are turned on in the car when you reconnect to the battery – a spark may occur when you replace the second battery terminal and ignite the battery gas.

Types of caravan battery chargers

A basic battery charger incorporates a transformer and rectifier, to change lines from 110/220 volts to alternating current from 12 volts to direct current, and allows the power supply to provide charging current at a speed determined by the battery status.

In the case of a good battery, the charge rate can be in the order of 3 to 6 amps with a normal household charger.

A battery at the end of its life cannot accept any recharging, and will not, in any case, hold a charge.

Some chargers come with a high and low switch, to give a choice of two charge rates – typically 3 or 6 amps – in case you want to give the battery a boost at 6 amps rather than a charge. longer at 3 amps.

Many have a charge indicator which can be a warning light, or a gauge showing the charge rate in amps.

Note that the power cord on all chargers should be merged. If it is not, use a fused three-prong plug. As an added precaution, install a fuse cable from the lead line to the battery.

The bottom line

In short, to test for proper operation of a caravan battery charger, first, plug the 12-volt charger into a power outlet. Then, insert the red terminal (+) of the multimeter into the positive pole of the charger, and the black terminal (-) into the negative pole of this 12-volt charger.

Please let us know if you have any questions or comments about testing a caravan battery charger. 

FAQ on How do I test my caravan battery charger?

How do you know if the battery is dead?

To know if the battery is dead or not, detach the battery from the screwdriver by unclipping it. The process is practically similar from one accumulator to another. Determine if the battery has a charge indicator. The indicator light is often presented in the form of a battery as on all portable electric devices.

Which amperage for the battery charger?

A basic charger usually charges around 2 amps – and therefore takes 24 hours to deliver the 48 amps needed to fully charge one. But there is a wide range of chargers with different charge rates on the market – from 2 to 10 amps.

How do I know if an adapter is working or not?

To know if an adapter is working or not, insert the red (positive) wire into the centre of the adapter shaft, then touch the black (negative) wire to the metal part on the outside of the rod. Read the display. If the adapter is working properly, the meter should read within 1/2 volts of the rating.


Was this helpful?

Thanks for your feedback!