Keeping battery topped up

[Nathan]

I put my Swift Challenger Sport 586 on hook up to charge the battery while it was laid up for winter. After 36 hours charging I unhooked and checked the control panel above the door which showed the levels were charged up to 13 instead of the usual 14. Is this normal or is the battery not charging properly?

 

[paws]

Hi Nathan, its a good question you ask.
Here's some general thoughts on batteries and charging....

When a battery is connected to a battery charger the voltmeter will often show a voltage of around 13 to 14v....I say 13 to 14 because voltmeters can be inaccurate and the ones generally fitted to caravans are notoriously inaccurate!

When the battery charger is disconnected then the voltage of the battery ( if fully charged) will generally stabilise to around 12.6 v or so over a 24 hour period. (quicker if a load is applied) and this state of charge/voltage would indicate a fully charged battery.
A voltage reading of 12v ( offload) would indicate a battery around 75% discharged and in grave danger of being damaged permanently if left at this voltage for very long.

If the voltmeter is showing and maintaining 13v (offload) it probably means the battery is fully charged..... the important thing is that when the EHU (Charger) is reconnected the voltage on the meter should show an increase in voltage over and above the 13v previously shown.

Batteries can be funny chaps.... wiring to and from them involve voltage drops, batteries deteriorate with age some vol meters are not terribly accurate, temperature affects the figures.....That's why we often use expressions like...around so many volts etc rather than giving figures to one or two decimal places...
Hope this helps and is not all as clear as mud!
Regards
paws

 

[Damian]

Never trust the on board voltmeter in a van, they are notoriously inaccurate.

Invest in a multimeter and measure battery voltage at the battery terminals.

 

[ProfJohnL]

I echo Damian's post,

I would add that don't buy the cheapest meter you can find on the internet because there are literally hundreds if not thousands of low cost digital multimeters coming out of the far east, and some are inaccurate, some are dangerous and some are both.

Its better to go to a reputable source in the UK ( For example Maplin,co,uk, screwfix.com) where at least the products should meet the minimum safety standards, and be at least reasonably accurate. You can still get a reasonable meter for about £10 to 15 that will out perform the built in meter in a caravan.