power leak

[rhodyrunwv]

1973 29' Airstream has mid-bath, bedroom in rear
There is a power leak somewhere in circuitry of the middle section. Any ideas about what may be grounding out? Have checked everything I can think of.
Thanks!
rw

[nickcrowhurst]

First, a few questions: (assuming this is a 12 volt question, not a 120 volt AC question.)
1. What are the symptoms that have lead you to your diagnosis?
2. Do you have a multimeter that can measure current, preferably to 10 or 20 amps?
3. Do you have the wiring schematic from your Airstream manual, showing the routing and color-coding of the wiring in your trailer?
4. Do you know where the 12 volt distribution panel is in your trailer?
5. Do you know where the 12 volt disconnect switch is in the trailer?

If the answers to 2, 3, 4 and 5 are all "yes", then I suggest:

(a) Disconnect the trailer from any 120 volt A.C supply.

(b) Turn off all the 12 volt drains in your trailer (disconnected from the tow vehicle), including the LP gas alarm, lights, furnace, any control panel, any radio, TV , entertainment center, and the refrigerator. (RV refrigerators often need a 12 volt supply to run, even when plugged into 120 volts.)

(c) Turn off the 12 volt disconnect switch. Disconnect the main battery cable from the 12 volt distribution panel, and connect the +ve lead of your ammeter to the main battery cable, and the -ve ammmeter lead to the connection post where the main battery lead had been connected. Bind these connections with insulation tape, so that no metal parts can short out. (A dead short from the battery at about 100 amps will have consequences, in spite of a thermal cut-out in the cable).

Turn back on the 12 volt disconnect switch. If you have turned off every device, no current should be showing on the ammeter scale. If there is a current drain, look at the busbar which is 12 volts +ve live from the battery supply. You will see several wires attached to this busbar. These are the supplies for all the various 12 volt circuits in your trailer. Remove them, one at a time, until you find the one or more circuits which had been causing your drain. After consulting your wiring schematic, you should be well on the way to identifying the culprit. You can switch on various 12 volt components in the trailer, one at a time, to check their current consumption, but be careful not to exceed the current capacity of your ammeter.
For an idea of typical current drains of various devices, I suggest you look at this thread:
http://www.airforums.com/forum...ter-15625.html?
Happy hunting!
Nick.

[rhodyrunwv]

In a message dated 5/27/2006 5:56:54 PM Eastern Daylight Time, Rhodyrunwv writes:

1. What are the symptoms that have lead you to your diagnosis?

measurable - 1.3- 1.5 amp current flowing when all fixtures on that line are appearantly turned off.

2. Do you have a multimeter that can measure current, preferably to 10 or 20 amps?

yes, but one that measures 0 to 10 amps

3. Do you have the wiring schematic from your Airstream manual, showing the routing and color-coding of the wiring in your trailer?

I have the manual, but schematic only details running lights and pre-distribution pannel wires. After the 4 buss fuses there are no details of their distribution. Only there fused current limits. the 20's and a 15amp My difficulties are on the 2nd fused circuit (20 amps) off the buss and that provide current to the bathroom light, middle hall light, a bathroom fan, and that mysterious 1.3 amp draw I can't identify let alone turn off. How do I find it? Are there any typical places these circuits ground out? I went as far as to remove all bulbs and disconnect switches. I feel confident it is somewhere in the wiring where I can't get at it without pulling up walls and floors.

4. Do you know where the 12 volt distribution panel is in your trailer?

yep

5. Do you know where the 12 volt disconnect switch is in the trailer?

yep

If the answers to 2, 3, 4 and 5 are all "yes", then I suggest:

(a) Disconnect the trailer from any 120 volt A.C supply.

did that

(b) Turn off all the 12 volt drains in your trailer (disconnected from the tow vehicle), including the LP gas alarm, lights, furnace, any control panel, any radio, TV , entertainment center, and the refrigerator. (RV refrigerators often need a 12 volt supply to run, even when plugged into 120 volts.)

did that

(c) Turn off the 12 volt disconnect switch. Disconnect the main battery cable from the 12 volt distribution panel, and connect the +ve lead of your ammeter to the main battery cable, and the -ve ammmeter lead to the connection post where the main battery lead had been connected. Bind these connections with insulation tape, so that no metal parts can short out. (A dead short from the battery at about 100 amps will have consequences, in spite of a thermal cut-out in the cable).

Turn back on the 12 volt disconnect switch. If you have turned off every device, no current should be showing on the ammeter scale. If there is a current drain, look at the busbar which is 12 volts +ve live from the battery supply. You will see several wires attached to this busbar. These are the supplies for all the various 12 volt circuits in your trailer. Remove them, one at a time, until you find the one or more circuits which had been causing your drain. After consulting your wiring schematic, you should be well on the way to identifying the culprit. You can switch on various 12 volt components in the trailer, one at a time, to check their current consumption, but be careful not to exceed the current capacity of your ammeter.
For an idea of typical current drains of various devices, I suggest you look at this thread:

did all this and narrowed it down to one fused circuit. Everything is turned off and still 1.3 amps are flowing from the fuse into this one circuit. I know their has to be a leak somewhere probably on to the trailer frame from some wire or fixture but can't seem to locate. I figure 1.3 is quite a lot of current not to be able to identify but so far no luck

[nickcrowhurst]

That's a large current drain. Is there a forum member out there with a more detailed wiring schematic, so that we can see if this circuit feeds more than these two lights and the fan? It would be unfortunate to start tearing out interior panels if there is some other device causing the problem.(e.g climate control circuit on a fridge door surround, TV antenna amplifier.) If this circuit does only feed these devices, and the current drain occurs when the wires to these devices are disconnected, then it seems you probably have a short from the live wire to the trailer frame in some concealed place. The only way I can think of to pin this down any closer is for one person to watch the ammeter, while another slaps the internal trailer skin with the palm of one hand. Slap in all the places where the wiring is likely to run, and see if the amperage changes temporarily. Failing this, you may need to run a fresh cable from the bus. New wire can be slipped behind panels, once the pop rivets have been drilled out with a 1/8th inch drill bit. Good luck!
Nick.

[overlander63]

Could be a motor that is frozen, but still on. Is it the circuit with the bathroom fan, or kitchen fan in it?
I have a schematic for you, but I am headed out the door to work. If you still don't have a schematic by tonight, I will scan and post it here for you.

[87MH]

1.3 amps - about 17 watts, depending on the battery charge voltage.

Below is a schematic of a '78 31' trailer - hope it is of some use.

Double click on the image - you should be able to enlarge it to a useable size.

[azflycaster]

The diagram I have (75) shows a ceiling light, bathroom light (2), bathroom exhaust fan and a 12 volt outlet on that circut. Maybe someone left something plugged into the 12 volt outlet. My wife has curling iron that pulls a few amps!

[nickcrowhurst]

I have an idea. This 17 watt power consumption will be producing considerable heat. When the trailer is out of direct sunlight, and all lights and appliances are switched off, scan the inside and outside skins and all the lights and fans with a digital infra-red thermometer. I use the cheap one from RadioShack, and, like many others on this forum, find it invaluable for checking on wheel bearings, brake adjustment, tire condition, etc, at every stop during a trip, and after a brake or bearing service.The device can be purchased for $50 at
http://www.radioshack.com/sm-non-con...i-2103171.html
17 watts is a lot of heat in a confined space, and the thermometer shows readings to one tenth of a degree fahrenheit. This link, at post 31, discusses this in more detail:
http://www.airforums.com/forum...ighlight=infra-
Nick.

[overlander63]

Originally Posted by azflycaster

The diagram I have (75) shows a ceiling light, bathroom light (2), bathroom exhaust fan and a 12 volt outlet on that circut. Maybe someone left something plugged into the 12 volt outlet. My wife has curling iron that pulls a few amps!

If I had to guess, I would say the bathroom fan is "on", but not "running", although I had a 12v outlet with a short that did as you have described.

[Sean Hegan]

Great resource. Will this schematic apply to a 77 31' rear bath? I am having a similar inquistion going on.
Sean

[Sean Hegan]

Nick,
I can't find my 12 volt disconnect switch in the trailer. I have a 77 31' Soveriegn rear bath. Any clues?
Sean

[nickcrowhurst]

Sean, in my trailer, it is behind the couch seat under the front window, slightly to the kerbside of center. The cables from the battery or batteries to the disconnect switch are heavy duty, heavy in weight, and expensive. The switch should thus be very close to your battery or batteries. I hope this helps. A forum member with the same model trailer as yours would be of more help. Good luck.
Nick

[Sean Hegan]

Thanks Nick. I can't find a switch. Just the the quick disconnects in the battery compartments. I'll sniff out the 31' 77 soveriegn crew. Thanks again.
Sean

[Sean Hegan]

Dennis,
I'm having some difficulty reading this diagram. My arms are shrinking and cant' focus clearly on the colour codes. I have a 77, 31', Soveriegn (international) with the rear washroom. I have the owners manual but there is no diagram with the detail that yours boasts. Where did you get that diagram? Any chance of getting one for my coach?
Thanks.
Sean

[Sean Hegan]

Dennis,
I'm having some difficulty reading this diagram. My arms are shrinking and cant' focus clearly on the colour codes. I have a 77, 31', Soveriegn (international) with the rear washroom. I have the owners manual but there is no diagram with the detail that yours boasts. Where did you get that diagram? Any chance of getting one for my coach?
Thanks.
Sean