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The Leisure Battery

Have you ever had a problem with the leisure battery on your caravan or motorhome? Maybe you’ve been wondering what the difference is between a leisure battery and a car battery? If you are relatively new to caravanning and haven’t had to deal with the battery yet, chances are you’ve never given it a second thought. Whichever category you fall into, owning and holidaying in a caravan means you will need to deal with a leisure battery regularly, making a basic level of knowledge invaluable. Aside from enabling you to maintain your battery in a way which will prolong its life and keep your costs down, being able to recognise the signs of potential damage in a leisure battery is essential for the safety of anyone using your holiday accommodation.

What is a leisure battery?

A leisure battery is the power source for the 12V appliances and equipment in a caravan or motorhome. These batteries are designed to provide a steady level of power over a prolonged period of time and are used by the lights, T.V, water pump etc.

If you intend to buy a brand-new caravan, bear in mind that leisure batteries normally are not supplied with new builds, although you will usually get one included in a new motorhome. Check with the dealership when arranging the purchase to make sure you have time to source a leisure battery before you plan to take your first trip, if one isn’t due to be provided.

Are leisure batteries the same as a car starter battery?

No, a leisure battery and a car battery are two very different power sources. It may be possible to use each of the batteries in the other’s place in the short term, but it is not advisable due to the different ways in which they work.

A car battery is designed to provide a burst of energy to start the engine when required, whereas a leisure battery will release a lower level of energy over a prolonged period of time in order to power appliances.

Due to the difference in intended purposes, leisure batteries and car batteries are not constructed in the same way. A car battery has thinner plates and different separators, which mean that it is not as well-equipped to deal with a prolonged period of use for a lower level of energy, and vice versa for leisure batteries.

Leisure battery types

Most leisure batteries are lead-acid batteries, although there are some alternatives. Within the category of lead-acid battery, there are a few different types available:

As well as these lead-acid batteries, there are a few alternatives which may be used as leisure batteries in certain circumstances.

  • Gel batteries – These are used in vehicles such as jet skis and quad bikes, which have a higher than average risk of crashing. The use of gel inside the battery removes the risk of damage from being tipped over and, therefore, the risk of injury from leaking corrosive acid. Some imported caravans and motorhomes are now fitted with gel batteries for extra protection in the event of an accident.
  • AGM batteries – We mentioned these briefly in the section about car batteries v leisure batteries. AGM, or Absorbent Glass Mat batteries comprises of lead plates and compressed glass fibre in each cell. Combined with specific manufacturing processes, this makes the battery capable of a much longer lifespan than a lead-acid one. However, it is also more expensive to produce. As well as being able to withstand a greater number of charging cycles, AGM batteries have the advantage of being functional as both starter and leisure batteries.
  • Maintenance-free batteries – While conventional batteries have removable caps to allow the acid levels to be checked and topped up with deionised water, some manufacturers are now producing what is described as a maintenance-free battery. This is a sealed unit which cannot be topped up, built due to the fact that batteries which are not charged in excess of 14.6V rarely need this done anyway. If 14.8V or more is used, it is important to regularly check the electrolyte level of a battery and replenish as required.


Why do I need a leisure battery?

You will need a leisure battery in order for most of the 12V appliances in your caravan or motorhome to function but, even if it wasn’t essential, there is a very good reason for choosing to use a leisure battery rather than powering the devices directly from a mains charger or similar. The secondary function of a leisure battery, aside from powering appliances, is to correct any irregularities in the power supply, keeping you and your appliances safe.

Lead-acid battery safety

Due to the flammable nature of batteries and the corrosive properties of the acid within, proper safety measures must be followed when handling batteries.

  • Ensure the battery is properly mounted and the gas escape vent correctly fitted at all times
  • Safety clothing and eye equipment must always be worn when inspecting a battery
  • High quality clamps should always be used to connect a battery to prevent any sparks from occurring and causing fire. Crocodile clips are not suitable for permanent connections

Getting the most from your leisure battery

  • Apply a thin layer of Vaseline or grease to the battery’s terminals
  • Always use high quality clamps
  • If spring-loaded clamps are used, ensure that their steel contact surfaces do not rust
  • Regularly check that the electrolyte level covers the lead plates on the battery. If not, top up with deionised water as required. Always wear full safety equipment when inspecting and maintaining the battery
  • Check regularly to make sure the gas relief tube remains fitted securely and correctly
  • Recharge the battery once it falls below 50% power. Never allow a battery to completely run flat as this can greatly reduce the lifespan
  • Remember to care for your battery when your caravan or motorhome is to be unused for a period of time. A trickle charger is a good idea in this situation
  • Never leave the battery uncharged. A white deposit, caused by sulphation, will form on the plates, rendering the battery unusable
  • Remember that a battery needs a charger with an output of at least 10% of the battery’s capacity. For example, a 90Ah battery will need at least a 9 amp charger. Any less will significantly reduce the capacity

Checking the battery’s charge level

While your caravan or motorhome may have a light or display to show the leisure battery’s charge level, these may not be particularly accurate. It is advisable to invest in a hand-held metre, which can be used to easily obtain an accurate indication of the charge level. The table below can be used as a guideline when carrying out the checks.

Meter Reading Approximate Charge Level
12.7V or above 100%
12.5V 75%
12.4V 50%
12.2V 25%
12V or lower Discharged


Prior to using the meter to check the battery’s charge, the following steps should be followed:

  • Switch off all electrical appliances, including alarms, fridges and clocks that run off the battery. Failure to do so will result in an inaccurate reading
  • Always remove the negative terminal first when disconnecting a battery
  • Never smoke near a battery
  • Do not use a charger on the battery or drive your motorhome for four hours before testing, as a recently used battery will give a higher reading

An alternative method of checking the charge level of a battery is using a hydrometer to measure the electrolytes in the cells. The reading should be between 1.1 (discharged) and 1.28 (fully charged).

To determine how long the battery can go between charges, check the capacity, which is normally measured in amp hours (Ah). An 110Ah battery will provide considerably more power between charges than a 65Ah one, for example, but will also take longer to recharge.


What affects a battery’s performance?

There are quite a few factors which may affect the performance of a leisure battery, including temperature, age and the size of the battery.

  • Temperature – The colder the temperature, the poorer the performance of the battery. The amp hours rating which is stated is based on a temperature of 25C, with each degree lower causing a 1% drop in performance. For example, an 110Ah battery operating in 15C temperature will actually perform as a 100Ah.
  • Age – Most batteries will not last more than around five years due to a decrease in performance over time
  • Consumption – If a high number of appliances are run from a battery, it will discharge quicker and therefore need to be recharged more often. This frequent recharging will cause the battery to degrade sooner.
  • Size – The more appliances you need to run, and the more power-hungry those appliances are, the bigger your leisure battery will need to be. For example, a motor mover will require a large battery. You should also consider the time of year you tend to travel, due to the reduction in performance caused by cold weather.
  • Discharge rate – The Ah rating provided by the manufacturers of batteries normally assumes a discharge time of 20 hours. The capacity will normally be provided at two or three different levels, such as 95Ah at a 20 hour rate, 80Ah at a 5 hour rate and 105Ah at a 100 hour rate.

While all of these will influence the performance of the battery, it is important to remember that there are countless other factors at play.

My battery stinks!

Batteries can sometimes emit a rotten egg smell when recharging, which is less than pleasant for those using the caravan or motorhome. This generally indicates that the battery is being overcharged. Should you detect such a smell, check if the battery feels hot to the touch. If so, the battery is being overcharged and is in danger of being irreparably damaged.

If you do get an eggy smell, remember that this means that gases are being emitted and, as such, could potential ignite or explode. Never disconnect the battery from the charger while it is connected to the mains, as this may cause a spark and disastrous consequences.

Leisure battery explode

You should always be aware of the temperature of your battery while charging as a hot battery normally means there is a problem.

UPDATE – February 2016 – National Caravan Council Verified Leisure Battery Scheme

The National Caravan Council (NCC) has introduced a Verified Leisure Battery Scheme to give caravan and motorhome owners peace of mind when purchasing a new leisure battery. If the battery you are considering displays the scheme’s logo, you will be able to ascertain what level of use it is suitable for and, of course, that it has been deemed reliable and fit for purpose by the NCC.

Why was the scheme launched?

As leisure batteries involve a significant financial outlay, up to approximately £200, and it had been found that some products being sold as leisure batteries were, in fact, intended for use only as starter batteries, the National Caravan Council and some leisure battery manufacturers teamed up to create an easily understandable verification scheme.

When purchasing a verified leisure battery, caravan and motorhome owners can rest safe in the knowledge that they are paying for a reliable, fit for purpose leisure battery. Not only does this indicate a sensible purchasing decision in financial terms, it also provides some level of safety assurance.

How are leisure batteries categorised under the scheme?

The three categories of verified leisure battery are as follows:

  • Category A – Higher storage capacity batteries which have been designed for use by those caravan and motorhome users who tend to operate away from an electrical hook-up point
  • Category B – Designed for users who will avail of an electrical hook-up on the majority of their trips, but will also require greater power capacity. Devices such as motor movers are likely to require a Category B battery even if electrical hook-up is used
  • Category C – The final category covers verified batteries suitable for use when electrical hook-up is not available for a short time only

NCC Verified Battery Scheme

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