Phantom Draws

[Joe Cannarozzi]

We have a relatively simple electrical system on our 86. I have been pulling my hair out trying to locate a phantom draw on both the 12 and 24 volt house battery banks.

My question is are the DC amp gauges themselves a draw? They are analog, not digital, and are only lit if the light is switched on.

[VegasDogMan]

A DC Ammeter is not a load until such time you close the circuit.

Can't draw it here but follow my text below....

(12V Battery + )-------(Ammeter)------(+)----(Switch)----(Load)----(Gnd)

If Switch is open no current flows from Battery to Ground and consequently no current through Ammeter.

Close Switch and Current draw in circuit is 12volts divided by Load in Ohms = Current in Amps.

[Jon Wehrenberg]

Joe,

This is a stretch but on our old coach the previous owner connected the Racor heater to the battery bank and since it never went through the battery disconnect switches I went crazy until I found it.

Look for any wires that are connected to power ahead of the disconnect switches.

[Omnitech]

You can check for parasitic draw on individual wires using a good AC/DC clampmeter like the Fluke 337. If you have shut down all of the circuits that you can and still have a draw, find the wire that has an amp draw and find
out where it goes. Some converters and (gasp) customers have modified the coach chassis from original wiring, but at some point there is a connection you can trace it to.

I would begin at the batteries first, as some branch circuits (even smaller ones) start there. Some converters even have sub-circuit panels in close
proximity to the batteries (ie: Marathon).

Contact me if I can be of any help. omnitech_nick1@yahoo.com

Nick

[bill&jody]

in our bus, there is a relay that connects/disconnects all dc components from the batteries. that relay draws a bit of current solely to allow other things to have the POSSIBILITY of connecting to dc. there's a switch over the entrance to operate it. i haven't measured its requirements but since it's a pretty beefy relay (needs to have fast, positive connect and release due to (potentially) high currents), i would suspect an amp or two. and yes, it stays hotter'n a $2 pistol.

seems like a latching relay would have been a better idea.

wmm