Charging Caravan Battery Whilst Towing

Jul 21, 2007
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My electric panel gives a make of ECM or EMC. It has a battery charge level indicator; three switches (one switch for aux; one for pump; and the third one if for the battery off - car - van.

Sorry if this is a totally ignorant question but what position do I have this battery switch at when I am towing so that the caravan battery is charging as we go.

Your advice would be appreciated - thank you.

Linda
 
Apr 7, 2008
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First of all do you have a 12s white socket on your car or the later 13pin one ?

And what make / model & year of caravan is it ?
 
Jul 21, 2007
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Thank you for responding. We have a Swift Charisma 220 (2002 model). The caravan has two leads grey and black and we connect them via a converter to a single connection to our Volvo V70 (2009). Hope this is of some help.
 

Damian

Moderator
Mar 14, 2005
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It should make no difference where the switch is set as when connected to the car, the only 12v supply from the car is to the battery and fridge.

An internal relay cuts off all other 12v applications in the van.
 
Apr 7, 2008
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You will have to check the 13pin socket to make sure that you are getting power from the car check pin 9 ( with the car running ) on your car with a multimeter this is for charging your van battery, pin 10 is for the power to your fridge, if i remember rightly some 13pin wiring harnesses do not have the pins in / connected for the fridge so its worth checking that also..

Here is a link to a 13pin wiring diagram

If you have power there plug in your adapter & check that you have voltage coming through ther also,

Take a look here at 12n & 12s wiring diagram

If you have power to the appropriate pins couple, every thing back up & check the battery in the van with the multimeter, you will have to have the car running at at least 1500rpm for it to show that it is charging...

I do not know what way the switches need to be....

Have you got a hand book for the van....???

Did every thing work ok with your last car ????
 
Jul 21, 2007
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Thanks everyone, will come back to this posting tomorrow morning when I've had chance to digest everything.

Linda
 
Dec 30, 2009
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Checked the manual for 2002 swift vans and it states that the switch with car/van on should have 3 settings van, central and car. The switch should be in the central position whilst towing.

If you havent got a manual, look on Swift website click caravans and then manuals scroll down and you will see manuals for alot of years.

Kevin
 
Jul 11, 2006
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Is your car old enough to still have a dynamo Sproket?

If the engine is running so long as the charge warning light is not lit (and it shouldn't be) the alternator will be charging, even at tickover and the fridge supply line in whichever socket is being used will be active.
 
Nov 28, 2007
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Simple if you have a multimeter. Car and caravan connected, engine running. Measure the caravan battery volts and get some one to operate the switches. When the correct switch is operated the volts will increase. Probably from 12 - 13 volts, going to 13 -14v, you will see an increase.

This does assume that all your wiring is OK but the question was only with regard to the switches.

If you do not see an increase, switch off the engine, disconnect the connectors and if the caravan battery is still showing the same volts you have a wiring / connector / relay fault.
 
Mar 10, 2006
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Woody

What sprocket is referring to in a round about way, is the pull in volts for the voltage sensing unit, some units need more pull in volts to operate, once pulled in there is no problem, as the drop out volts is often lower than the pull in voltage, revving the car slightly ensures 100% alternator out put, although modern alternators give out about 90% output on tick over, in general.

In addition some voltage sensing units are adjustable,to overcome this problem.
 
Mar 10, 2006
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The easy way to check the battery is charging is to test across the battery terminals with a multimeter, set to 12v dc range, with the car engine RUNNING,and 13pin connected, you should get between 13.5 volts up to 14.8 volts, in general.
 
Apr 7, 2008
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Yes ! i remember the old dynamo.

At idle, the alternator is 12 volts, so the battery isn't being charged.

Depending on what you have turned on the battery will be discharging.

The car has to be above about 900-1200 RPM so voltage goes up to 13.8 to 14.4 volts to create a forward bias across the battery and put the battery into a charging state.
 
Jul 21, 2007
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Good Morning everyone.

What an awful lot of information.

Our car is a 2009 Volvo V70 R-design diesel with a manual gearbox.

I have to admit that 95% of what you advised went straight over the top of my head. But Trucker's response came up with the information I needed.

Because I don't tinker with cars or electrics on caravans (just wash and polish the caravan) I have the van serviced at UBC Gosforth and had the towbar and electrics fitted to the car by Hedley's of Durham. I rely on the expertise of the professionals and have to trust them to make certain everything is OK.

But many many thanks for responding and taking the time to offer advice.

Off to see if I can find the manual for the van. Thanks again Trucker.

Kind regards - Linda
 

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