Preserving Your Motorhome Battery - The Camping and Caravanning Club
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Preserving Your Motorhome Battery to Power Your Security Devices

There are lots of different security devices available to motorhome owners, including wheel clamps, alarms, immobilisers and tracking devices. Some of these devices will require powering from your motorhome battery, which is just one reason why the maintenance of your motorhome battery is so important. Having an inoperable battery causing the failure of an electronic device may invalidate your claim.

Most motorhomes have two types of battery; a starter battery and a leisure battery. The starter battery is used to start and run the engine, whereas the leisure battery is a deep-cycle battery which provides steady power over a long period of time.

Starter batteries provide short, sharp bursts of power which allow you to start the engine of your motorhome. They are charged by the alternator when your engine is running. If your motorhome is regularly driven, these batteries do not require much maintenance, however you may find that they discharge when not driven in a while so you cannot start the engine. All batteries begin to deteriorate if left to discharge too many times and they can be expensive to replace, therefore we would recommend driving your motorhome for about one hour every 3-4 weeks if possible to best maintain its charge. If you do find that you cannot start the engine, have a look to see if you have a ‘battery boost’ switch. The purpose of this is to enable starting the engine from the leisure battery when the starter battery is flat, saving you from digging out the jump leads! You could also look into a small solar panel installation purely to keep the starter battery topped-up in storage.

Your leisure battery provides a continuous, 12 volt DC supply which is used to power some security devices, in addition to your motorhome internal lights, water pumps and many other appliances. The leisure battery is what’s known as a deep-cycle battery; the most common type is a flooded lead acid battery and come in two styles, serviceable with removable caps for maintenance or maintenance free. Serviceable leisure batteries need much more careful maintenance than your starter battery, but it’s often hard to know just how to properly care for them. Leisure batteries will discharge over time even if there are no lights, appliances or accessories switched on. This is because most modern vehicles have devices that are constantly consuming small amounts of electricity, such as the memory for radio settings or gas detector and security devices such as alarms and immobilisers. It is important that these devices still have access to power when the motorhome is not on to protect your vehicle from thieves effectively. Batteries therefore need to be regularly charged, as partially or completely discharged batteries deteriorate much more quickly and will soon need replacing.

Most motorhomes use one or more 12v leisure batteries; careful maintenance is required whatever the set-up to keep batteries running well, they can be charged in four ways:

  1. By hooking up to a mains electric supply
  2. From the charge of an alternator when in motion
  3. From a leisure battery charger when at home
  4. From a solar  charger

If you are on a campsite, it’s likely that you will hook up to the mains electric supply to keep your leisure battery fully charged and when your motorhome is at home or in storage ideally you should use a dedicated leisure battery smart charger to maintain it. Solar-powered chargers are increasing in popularity for many reasons and generate energy to charge the battery at home and on the go, even when skies aren’t so blue! If you do use solar panels, you may need a few other components to help with your battery maintenance. For example solar panels may generate more power than your battery can handle and this can cause serious damage, so you should invest in a solar charge regulator to keep charging voltage at the appropriate level. You should also regularly check the battery connections to solar panels if you use them. 

Other ways to preserve your motorhome battery

Aside from ensuring your batteries are regularly charged, there are lots of other ways you can preserve your motorhome battery:

  1. Regularly inspect the cleanliness and electrolyte levels and ensure that protective clothing and eyewear is worn at all times to prevent any battery acid from damaging your clothes and burning your skin.
  2. Regularly check the state of charge using a direct current voltmeter. A reading of 12.7v indicates a fully charged battery, 12.3v indicates that it is part-discharged and any reading below 11.8v shows the battery to be fully discharged. We would recommend any partially or fully discharged batteries be recharged up to their optimum 12.7v as soon as possible. Batteries left in a discharged state even for a short time may suffer irreparable damage
  3. If your motorhome is used occasionally and stored largely without power, you should check the water levels in your battery at least every 90 days. If your motorhome is kept charged whilst in storage, check water levels once a month. Top up water levels where necessary with distilled water, which is available from most motor accessory shops, unless your battery is maintenance free.
  4. Look out for any corrosion on the wires, cable terminal connections, and any metal surfaces around the batteries, and if you find any, use battery terminal cleaner spray to neutralise the acid that’s the cause. Once it’s dried, we would advise that you also coat the terminals and metal areas with a battery terminal protector spray. As with the distilled water, you can find both in motoring accessory shops.

Loss of power could not only shut down your security devices, but is also a common cause of motorhome breakdowns, so it is vital to look after your batteries. You can preserve both the starter and leisure batteries for four years or more if you maintain them well using our advice above with your manufacturer guidelines.