Why does my caravan battery keep going flat?

In this blog post, we will answer the next question: Why does my caravan battery keep going flat? We will discuss the reasons why your caravan battery discharges so quickly, and tell you how to check and prevent it. 

Why does my caravan battery keep going flat?

If your caravan battery keeps going flat it may be that there is a problem with the battery charger or the battery itself. You must check both and find where the leak is. 

  1. To check the charger of your caravan battery, connect it to a multimeter. 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.

  1. To check if the caravan battery works properly, measure 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.

A battery loses a little more of its efficiency each time it is allowed to drain before recharging it. Even though you don’t really realize it when it comes to a slow-discharge battery, the more time passes the more damaged the battery.

How long does a caravan battery usually last?

A caravan battery will last between five and 10 years, depending on how you use it. The charge rate of the caravan battery is a very important factor to consider when determining how long your battery will last. 

The limit of this in terms of discharge compared to that it usually endures is also important in determining the usage time of this cellar battery for motorhomes. It also allows you to know the number of cycles it can perform.

Let’s discuss two possible scenarios:

  • A slow discharge battery is capable of performing between 2000 and 2500 cycles when properly recharged, that is so that the discharge level is not less than 50%. Its lifespan in this case is between 6 and 10 years
  • On the other hand, when it is allowed to go up to 80% discharge, the battery will only be able to perform between 1000 and 1500 charge and discharge cycles. This means that the usage time of it will not exceed 5 years.

Some batteries are able to withstand up to 100% of discharges. However, it should not be abused, as it could deteriorate quite quickly and drastically shorten its usage time. 

A battery loses a little more of its efficiency each time it is allowed to drain before recharging it. Even though you don’t really realize it when it comes to a slow-discharge battery, the more time passes the more damaged the battery.

Avoid over-discharging the caravan battery

As a general rule, open lead batteries support between 20-300 charging cycles, GEL 400-500 batteries and AGM 600-800 technology batteries. The useful life of your solar battery is closely linked to the% discharge that it has undergone, therefore, you should avoid discharges below 75% even when long periods of time go unused. 

Many charge regulators incorporate a display that allows you to see the percentage of battery charge, but if your charge controller does not have a display, it is always possible to purchase a battery monitor so that you can strictly control the status of your accumulator.

How to take care of the battery of your caravan?

There are many battery failures and changing batteries has more science than it seems (normally when a battery is changed, even if the auxiliary battery is not touched, it is time to change the other), so if you don’t want to have to do it, We advise you to read the following tips well:

  • The batteries must not be allowed to drain. It is more in certain types of batteries because AC is detrimental to its operation.
  • To prevent the auxiliary battery of your caravan from deteriorating, make sure that the motor battery does not stay below 50% and that the auxiliary battery always has more than 20% charge (with exceptions).
  • For environmentalism and good sense, save energy. You never know when you will need that extra consumption that you have not anticipated.
  • Recharges the battery when it is running to one-tenth of its capacity.

And these special precautions for winter:

  • If your caravan battery is not used during the winter, it discharges about 3% per month.
  • To avoid battery drain, recharge the batteries well, put them in a warm place, and test them regularly. Cuts to 12V at the control panel.
  • Sometimes the presence of the solar panels is enough to hold the charge.

How to make your caravan battery last longer?

If the capacity of your battery rises to 100Ah, and your energy consumption is higher (this is the case if you have additional energy-intensive equipment such as a TV, air conditioning, etc.), you will have to review your consumption at lowering or increasing the energy capacity of your motorhome.

Tip: If you want to make your battery last, it is best not to use more than half of its capacity and to fully charge it between two discharge cycles.

Example of electricity consumption with additional equipment:

• A television: 4 Amps -> 4 hours: 16Ah

• Its demodulator: 1.5 A -> 4 he: 6 Ah

• Electric heating in winter: 1.2 A -> 12 h: 14.4 Ah

• A 50-liter compression fridge: 1.4 A -> 24 h: 25.4 Ah

By adding the standard and additional equipment, the daily consumption this time amounts to 100.15 Ah. Or with a 100 Ah battery, one day of autonomy.

And that’s without counting the recharging of computers (like us via a converter)!


It is essential to always check your caravan battery and your caravan battery charger for possible leaks. If you spend a certain time without taking the caravan, it is recommended to disconnect the terminals so that there is practically no consumption.

Also, if your caravan battery keeps going flat, avoid using high-consumption appliances while on it. Appliances and air conditioners cause rapid discharges of your battery in a very short time, so it is better not to abuse their use. 

Try to use efficient appliances that optimize consumption but, if you are still going to use this type of equipment for a long time, make sure that the quality of your battery allows it.

If you have any questions about how caravan batteries operate, please let us know!

FAQ on Why does my caravan battery keep going flat?

How long does it take to recharge a battery?

Recharging a battery to its full capacity can take up to 40 hours. Of course, this cooldown assumes it’s completely empty. It will also vary depending on its capacity and use. The best way to recharge the battery is via AC power.

What is a smart battery charger?

Smart battery chargers are based on the latest developments in technology and aim to simplify the task of users. Also, this type of charger analyzes the type of battery and its condition throughout the charging process.

What is a booster to charge batteries?

A Booster auxiliary battery charger is electronic equipment capable of taking the charging intensity of the vehicle’s alternator and generating a great load intensity towards the auxiliary battery, the most efficient chargers produce between 25 and 40 Amps PER HOUR direct to the auxiliary battery.

How do you recharge a caravan battery? 

The batteries are recharged automatically thanks to the energy generated by the motor. First, the main battery is charged and when it is fully charged, it sends current to the auxiliary battery.


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