OK;
I have a general question about electrical systems in my Airstream, if that is possible... I know electricity is a complex subject and I promise I am not going to run out, buy stuff, plug it in and set myself on fire or blow myself up. We are planning to have someone else do the electrical in the Airstream when the time comes, with the possible exception of pulling wires and installing switches and plugs. My husband can do basic electrical stuff, but for the most part he has someone else do it in his line of work doing interior remodeling. So I hereby swear we have a very healthy respect for the power and potential danger of electricity and this is for purposes of my understanding ONLY.
FYI, we are rewiring the entire trailer with all new stuff. I just want to know more about the system so I can get the concept. I am looking at my electrical diagram in the manual for my '67 and I see the following, and I'm going to post what I think I know of these things:
Battery: This is what we'll be using for electricity when we are boondocking. Charged up by shore power.
120 V panel: This distributes and manages the flow of electricity coming from shore power while plugged in.
Low Volt Distribution Panel: This does the same thing, only from the battery, which is 12 volt, like the voltage in your cigarette lighter.
Univolt: This converts or inverts (or both), 12v to 120v and vice versa. Or it does only one, and there's something else that does the inverting or converting. Remember I'm looking at my original '67 manual.
If someone knows of a basic web site or has some answers to how the entire system works, so I can learn more, I'd appreciate it. But here are two specific questions:
Specifically, what devices run from what source? What runs from battery and what from shore?
If certain things, or all, run from both, how do you switch back and forth?
My husband wants to know; can you rig the trailer electricity so it runs from your tow vehicle battery? Has it been done/is it a feature in the Univolt/Intellivolt?
Is there anything, wires etc. I might need to pull under the floor inside the belly pan while we have it open?
I know this is complicated. If I ask enough questions, I'll finally "get it", and it won't necessarily be on the first explanation. The light bulbs over my head have a mind of their own and go on whenever they feel like it. I appreciate anyone who wants to tackle this: just bear in mind this is for very basic clarity purposes and I don't expect to take the info and wire the trailer with it.
PS I read a great post by Boatdoc comparing batteries and wiring to plumbing which I can't find now, but I really liked it and it made sense.
I'm sure there are others out there who are electricity novices and can use the mental picture.
Thanks,
pinkflamingoes
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ingrid
1967 24' Tradewind #19104 ~ Forums #4449
Specifically, what devices run from what source? What runs from battery and what from shore?
All 12 volt items run from the battery.Lights, water pump, fans (heater), control boards etc.
All 110 volt items run fom shore power. Univolt, refrigerator, air conditioner, etc
Quote:
If certain things, or all, run from both, how do you switch back and forth?
What changes with shore power is how the 12 volts is produced. Without shore power it comes from the battery. With shore power it is produced by the univolt which also charges the battery
Quote:
My husband wants to know; can you rig the trailer electricity so it runs from your tow vehicle battery? Has it been done/is it a feature in the Univolt/Intellivolt?
It should do that now. There is a 12 volt charge line from the TV to the TT. On my Tundra the key must be on in the TV for this to work. The Univolt has nothing to do with this function. The Univolt converts 110 volt to 12 Volt. To go the other way (12 volt to 110 volt) you would need an invertor.
Quote:
Is there anything, wires etc. I might need to pull under the floor inside the belly pan while we have it open?
Don't want to hijack the thread but along the electrical line. I have a '67 as well. Just how bad is it to have aluminum wiring? How tough to replace it?
OK. So, everything essentially runs on 12 volts in the trailer. The difference is whether the original source of electricity is from a) shore power to Univolt or from b) battery.
Sounds like I need to read up on what a Univolt does, to understand everything.
Am I correct in guessing the inverter not something that came with the trailer, and is a later addition?
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ingrid
1967 24' Tradewind #19104 ~ Forums #4449
An important note: if you hire an electrician to put in the basic panels, make sure he understands that all rvs have a floating neutral. This means the ground and neutral are not bonded, like they are in your house. Many residential electricians don't know this.
Am I correct in guessing the inverter not something that came with the trailer, and is a later addition?
Hi Ingrid:
Here is my technically not-wholly-correct nemonic for remember the functions of an electrical converter and inverter. A converter contracts 120 volts to 12 volts, while an inverter increases 12 volts to 120 volts. They also switch AC to DC and vice versa as necessary, but that is not important for remembering which device contracts or increases voltage.
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Fred Coldwell, WBCCI #1510, AIR #2675
Denver, Colorado - WBCCI Unit 24
Charter Associate Member FCU
Vintage Airstream Club Historian
Airstream Life "Old Aluminum Adventures"
Those sites are a pretty good guide. Now, if your husband is happy pulling wires and installing plugs & switches... well, that's most of what's involved.
Unlike a house, where you might have subpanels and 240V circuits and all kinds of stuff, in the trailer you have one circuit-breaker panel with one 30A main breaker, with one 30A supply line coming in from outside. You need one 20A circuit dedicated to the air conditioner, and probably two 15A circuits for outlets, and that's it. The 30A supply line is 10/2 cable, the air-conditioner line is 12/2, and the 15A circuits are 14/2. It's really pretty easy, and any book on home wiring will tell you all you need to know about making junctions, correctly installing outlets, and so on. You can get a small circuit-breaker box and all the breakers & wire at Home Depot.
12V wiring is pretty simple too. You have a fuse panel or circuit breaker panel probably on or near the converter/Univolt. Since you have the interior skins off, you can probably just run one cable to each main 12V appliance (the manuals for them will tell you the appropriate cable size) and put each one on its own fuse or circuit breaker. Cable is cheap and not that heavy.
Lights are probably the trickiest 12V load. You need to add up how many lights of what wattage are going to be on the circuit, and make sure you have cable thick enough to handle the current. I think one of those sites listed before has a table for that. If you wind up above about 15A of lights, it's probably best to split it into two circuits. (But if you turn them all on at once, your battery will last about 10 minutes anyway... this is why people use fluourescent fixtures rather than incandescents.)
You probably want to install a few 12V outlets for things like cellphone chargers and laptop power supplies designed to run from a car 12V outlet.
Inverters are a really tricky subject. A small inverter like the $100 200W units you can buy at a car store can probably just be installed on the side of a cabinet with a dedicated 12V circuit for it and an on/off switch. That way if you need to run small 110V stuff - chargers, maybe a small TV - you can just use that. Once you want to do more than that - coffee makers, big TV, stereo, desktop computers - you get into specialized territory and thousands of dollars. But a small inverter is a handy thing to have around.
Finally, on running anything from the tow vehicle battery: when hooked up, with the engine running, at least with the typical wiring, your tow vehicle will charge the trailer battery... a little bit. Probably not that much. (In fact, I decided that it wasn't even worth connecting the tow vehicle battery-charger connection to the trailer.) But you don't want to use the tow vehicle battery for anything like running lights or appliances in the trailer for two reasons: one, starting batteries are not designed to be discharged very far, and much more importantly, two, if you discharge the truck battery you won't be able to go anywhere.
does anyone have a schematic or drawing for the control panel for a 1976 31' excella 500. The PO had taken all the wires off and lived entirely off of shore power. I would like to reconnect and be able to boondock, to include using my water pump and be able to read my gauges for the black/gray tanks, fresh water etc....
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