Hi guys,I have something 12v draining my batteries overnight. I have everything shut off on the camper, and it still drains them over night. Just put in new batteries as well. Still drains them.How do I start trouble shoothing this 12v electrical system to see what is causing the drain?

removes fuses from the distribution panel one at a time till the draw stops,if that doesn't work, start removing wires at the battery one at a time.

Make, model, and type of RV would really help zeroing in on your problem.

If your "camper" is a trailer, check that the emergency breakaway switch plug has not been pulled out. If it has, plug it back in (needs to be turned just right so it goes back in).

A DC clamp on ammeter is a very useful RV tool.

Remove all 12v fuses from the distribution panel;Take a multi-meter and put in the mode where you can see if a circuit is drawing a current (usually no more than 10A);Test each fuse and find out which circuit is drawing the current.Now trace back to the appliance; I had the same issue and it turned outto be the smake/CO2 detector and the fridge (even if it was off); My batteries would drain in < 2 days;Also - good point about the break away switch

12v Constant DRAW | Good Sam Community

20 Replies

IBcarguy
Explorer
May 16, 2018
Hey Honestbest333....did you ever figure out what was draining your batteries?
DiskDoctr
Explorer
May 10, 2018
I've used this model in fuse slots for the larger size, like older vehicles, works okay for those ;)

I don't have the link handy at the moment, but I posted up the difference in draw of the original incandescent bulbs and the new LED bulbs. It's in here somewhere... ;)
CA_Traveler
Explorer III
May 10, 2018
My car has micro2 style fuses which is not the mini style and I didn't see that style adapter.
SoundGuy
Explorer
May 10, 2018
CA Traveler wrote:
Nice useful tester however lacking some fuse sizes like micro and micro2 and others.

Seems Fuse Buddy offers a number of different versions, including this Fuse Buddy Pro which includes adapters for ATC and mini fuses.
bigfootford
Nomad III
May 10, 2018
Just a note....

If your fridge is running on propane and you have inadvertently switched the de-humidifier/anti sweat switch on it pulls a few amps.... Most fridges have them. Many folks do not even know that they have one.

Post the make and model or look up the feature yourself.

Jim
CA_Traveler
Explorer III
May 10, 2018
Yup Plus a light bulb in series with a shorted circuit is another diagnostic tool.
MEXICOWANDERER
Explorer
May 10, 2018
A fifty watt incandescent light bulb and twin wires bridging a disconnected house battery makes a fine diagnostic tool. I've used one of these since the sixties. Cheap. Easy to assemble and bullet-proof reliability. It works dimmer and dimmer down to less than a quarter amp drain. A 12 volt LED lamp could then be substituted for micro leakage detection.

Leaves the hands totally free. No fumbling.
CA_Traveler
Explorer III
May 10, 2018
Nice useful tester however lacking some fuse sizes like micro and micro2 and others.

And be aware that a few circuits reset when opened and will not have the same draw when reconnected.
DiskDoctr
Explorer
May 10, 2018
One of these is quite helpful to find draws and how much on each circuit.

I bought it here: https://www.amazon.com/305M-Fuse-Buddy-Mini-Tester/dp/B000W8FMXU
MrWizard
Moderator
May 09, 2018
battery disconnect are handy for storage situations

BUT

you need to find your problem, start by checking the vent fans are operating, can be turned on off, a failed fan that looks OFF not running might actually be stalled or shorted and using power

next pull all the house DC fuses from the fuse panel
check your battery again the next day, still charged ? then it is one of the fused circuits
put the fuses back in one by one
watch for sparks

fridge ? is it a 3 way, 12v 110v lp,
make sure the 12v option is off
do you have an inverter ? did it get left on ?

truck camper ? trailer ? pop-up ? motorhome ?