Battery drain

My starter battery is being drained by .4amps and it is the fridge that is doing the draining. Why does the fridge run off the starter battery ? Is this normal? why not the leisure battery? I have had to get a start from the ferry company the last 3 times .The fridge works perfect, is it a bad earth? I am confused, please help somebody. My van is a Lunar roadstar 780 built 2005.

 

Hi
i don't think that a 0.4 volt drain will reduce your starter battery to such a point that it will not have enough amps to start the vehicle , unless that is the battery is not holding a charge anyway.I assume that the ferry starts your vehicle after the crossing -not before -if that's the case the fridge is not powered by the alternator because the engine is not running. The fridge would be off even though you have selected the 12 v for the fridge whilst you was motoring to the ferry.
I would have your cab battery checked.

best of luck:thumb:

 

It is quite normal for fridge 12V to be off engine battery. This is because it is only used for ignition (negligible usage) or cooling (engine running only). I suspect, though, that the fridge is not the problem, but you are using one of those inaccurate current meters that don't have a proper zero. You probably just have a bad batt
ery. You'll need a multimeter and someone who knows how to use it to investigate further.

 

i always thought the fridge only run when the engine was running,,therefore it wont be on when you are on the ferry,,,,think you need a check on your main battery to see if its holding a charge and check your alternator is charging at the right rate too..

 

Is it an Autotrail?? The system has a drain of .3 amps if you leave the psu switched on .

 

our psu turns off once i start the engine, only comes back on when i press power button and its an Autotrail...

 

standard 3 way fridge wiring utilises a relay to prevent the engine battery draining with the engine off. if the fridge is drawing a current on 12v with engine off, check the relay

 

As the big 1 says..
The fridge should draw NOTHING when the engine is not running

if the fridge is drawing anything then the relay is stuck on


A bit of maths
All ball park figures but close enough

Lets presume you have a fairly large healthy cab battery that is a 100aH

Lets say once it gets below 20% capacity it will stand no chance of starting the engine
So you have 80aH to play with. ( unless you have a traction battery in which case you can go much lower.. say down to 10 % )

At a .4 amp drain that battery will be down to below usability after just 8 days of the van sitting.

If you have an alarm fitted that will also be drawing current too.. So about a week and you aint going nowhere !

 

What about the interior light.

 

if the fridge relay, with engine off, had jammed/welded closed you should see a drain of around 10amps from the starter battery.

thats why it only works with the engine running, otherwise the battery would be completely dead (as in destroyed) in around 8 to 10 hours

 

If it's like mine, the fridge interior light is wired to the leisure battery.