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Quote: Originally posted by Anne Calvert on 10/5/2006

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When we came to prepare our caravan for use in March this year the battery was completely dead. We used the van a lot last year - the last time was in December for a weekend and whenever we are away we always use electric hook-up. The battery was only 2 years old and was an expensive one - approx £50. I thought that it was recharging while we were hooked up to the electric on-site but it appears this is not the case. Should we be removing and recharging it?. If so, how often? I'd be grateful for any advice you can give. 

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In many caravans there is a small current drain from the battery even when everything in the caravan is switched off.  In some caravans this might be due to leakage back through the 12v power supply (like the Lunar Saturn I had until recently) or by a TV aerial amplifier that cannot be tuned off.  This can flatten the battery over a period of a month or two - so even if your battery was fully charged when you last used it in December, it wouldn't be by March.  

Many caravanners remove their batteries at the end of a season and recharge them once a month.  You might also find it helpful to fit a battery isolator switch if your caravan doesn't already have one. 

 

Quote: Originally posted by degsytroy on 15/6/2006

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I think I may have a problem with my Battery as well. I checked it on Sunday at the storage site and the battery was totally flat. I brought it home on Sunday and left it on charge overnight. ON Monday morning, it was reading 12.84V. I have kept a check on it daily and it is slowly dropping. This morning (Thursday), it had dropped to 12.13V. Is this normal or should it be holding its charge?  

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You'd expect some fall - but not that much in a couple of days.  It's probably crackered - sorry.

A word to all,  dont forget things like the Status amplifier for the TV.  You may have swithched off all the lights etc but this may still be on.

If the fridge is not working when plugged to car with engine running it sounds like you have a fault.

Ours was flat 2 weeks ago ......silly us.....we'd not switched it over to be charged by the EHU ....

Jenny

BATTERY PERFORMANCE:

It’s important to understand that, although batteries are described as 12-volt, in reality a fully charged battery should measure 12.6 volts after 24 hours of rest. A battery with a voltage of approx. 12.2V is only 50% charged and one reading 11.7V or less is, to all intents and purposes, fully discharged. Terminal voltages can be affected by various factors however, including the ambient temperature and cold weather will have a significant effect on a battery’s voltage and its ability to take and hold a charge.
Bear in mind too that, even if the voltage at a battery is 12.6V for example, the reading at the end of the wire or at the socket where an appliance is plugged in is what matters and there the voltage may be substantially less.

A battery’s performance is dependent on several factors including:
1) Temperature: both voltage and Amp/hour capacity will decrease significantly during cold weather. At freezing point a battery’s capacity is reduced by approx. 25%. The optimum operating temperature for a lead-acid battery is 80°F/27°C.
2) Rate of discharge: the faster a battery is discharged, the less the power that it will supply. For example, a 100Ah battery discharging at 2 amps per hour should, in theory, deliver power for approx. 50 hours. The same battery, when discharged at 50 amps per hour, will only supply power for approx. 1 hour. (These figures are only for illustration)
3) Amount of discharge: The more a battery is discharged, the less efficient it becomes and the harder it is to charge it back up to its full capacity. To ensure good performance and long life, leisure batteries should not be discharged by more than 40% at the very most.

The temperature factor is difficult to control but the other two can be dealt with by using a sophisticated charging regime. Ordinary chargers and on-board charging systems are not usually capable of providing this regime and, as a consequence, most batteries are never fully charged.
On-board chargers will charge the battery at around 13.8 – 14.2 volts and, although they will keep the battery in a reasonable condition, they won’t charge it up to the maximum. With a starter battery this isn’t a problem but, with a leisure battery, every Amp/hour wasted means less TV viewing time, less lighting or less water pumping. To achieve the maximum power from a 12V battery it’s necessary to look at additional pieces of equipment.

POWER MANAGEMENT EQUIPMENT:

Multi-stage battery chargers:

As previously mentioned, a charge of 13.8 volts is enough to maintain a battery at a reasonable level. It’s the voltage which most basic chargers work on and