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jugluss · 08-09-2004, 08:05 PM

if i'm always plugging into ac, why do i need a battery at all?

AirConditioner · 08-09-2004, 08:21 PM

Two reasons: (1) you need the on-board power to work the electric brakes if you ever need the break-way switch. (2)If your Airstream uses the Univolt power supply (110 volts to 12 volts 40 amps) then according to the design, the battery is needed to act a key part of the system to reduce the AC hum (ripple) that comes along with this older method of converting AC to DC. (ferro-resonant transformer method). It's not absolutely necessary, but it's way better with it in the circuit. Most folks who are often not on electric want to go the opposite way with at least two batteries.

58BUBBLE · 03-03-2005, 01:53 PM

I thought this might be a good place for for me to ask another one of my "inexperienced questions". I have a 1957 Bubble and as it sits now there is no battery. I can plug into 110 and my lights and sockets seem to work great, So if I can plug in or use my generator everything is fine. The problem is when I can't plug in or use my generator. (from the info I have gathered my unit didn't come with a battery system so I would have to install the complete system from scratch) I am very new to RV's and don't have a clue about how to install a battery and the necessary charger and then connect that to my system. Please help!

bryanl · 03-03-2005, 02:37 PM

For that 57 Bubble, if you don't have a ventilated storage place for a battery and the trailer isn't wired for 12v interior lights and whatnot, what I would suggest is that you get 2 AGM batteries and an inverter charger. Then continue to run everything on 110v AC.

The AGM type battery can be put in a non ventilated place inside the rig. The inverter should be rated for about 2 KW and have an intelligent battery charger and maintainer.

For a dedicated system like this, I would suggest running the two batteries in series for 24volts. Many good inverters can be found with 24v input. The reason for 24v is that current is reduced which makes losses and wiring less of a hassle.

The emergency brake thing can be solved in various ways if need be.

To find out particulars and howto and so on, visit alternative energy or solar energy sites such as Arizona wind sun.

**markdoane** · 03-03-2005, 02:37 PM

58Bubb,

That's a very broad question. The answer depends on how involved and elaborate you want to get.

The battery/charger arrangement in my '59 was pretty simple. The only 12V stuff was the lights, the vent fans, and the furnace blower. It all ran off a battery in a box mounted on the front of the trailer. The charging was done with a separate 12V charging line from the tow vehicle, there was no charger or converter. There wasn't even a 'breakaway' brake switch in 1959.

If you have time and want to learn everything, here is my favorite resource: http://www.phrannie.org/sources.html#1

58BUBBLE · 03-03-2005, 08:17 PM

So are the lights that work in my trailer when it's plugged in only 110? or will they work with either 110 or 12v?

**markdoane** · 03-03-2005, 08:25 PM

Look at the light fixtures. If they have two bulbs and two switches, they will operate either 120V or 12V.
These 'dual voltage' lamps were pretty common in the late 50's trailers. You just need to make sure you have the right bulbs in the right sockets, and make sure the 12V side has good fuses.

58BUBBLE · 03-03-2005, 08:38 PM

There are not 2 bulbs or any switches. Is it possible that there is no 12v at all in this model? Someone once told in me in another forum that they thought the main overhead light might run off of the vehicle power. That light turns on though when it is plugged in.

**markdoane** · 03-03-2005, 08:41 PM

Yeah, that's possible. Have you looked under the front couch for 12V wiring and fuses? Is there a two pronged plug socket on the right front side? Is there a battery box? If not, then it probably doesn't have a 12v system.

Here's what the fuse and wiring look like

58BUBBLE · 03-03-2005, 08:50 PM

I have that evact fuse setup that you have. there are 2 wires coming from inside the skin to the fuse block but the wires coming out are not connected to anything. Were these once connected to a battery?

**markdoane** · 03-03-2005, 09:07 PM

I really don't know about your bubble, but on my Tradewind, there was a battery on the outside, and a plug for power from the tow vehicle. The charging line ran through a fuse, then back outside to the battery, then to the light fixtures.

Here's a picture of the battery box and the charging line:

58BUBBLE · 03-03-2005, 09:15 PM

so does that mean your lights work only on 12volt and not when plugged in?

**markdoane** · 03-04-2005, 06:39 AM

Yes. All my light fixtures were dual voltage. So if it's not plugged in, the 120v side is dead.

58BUBBLE · 03-06-2005, 09:06 PM

Hey Don I made a discovery. I do have 2 seperate sockets in my ceiling light. I am assuming this the only 12v light that I have. I also noticed another plug socket on the outside front skin behind the tanks. It is a 2 prong rounded deal. What did they use this one for?

**markdoane** · 03-06-2005, 09:59 PM

That might be the 12V charging line I referred to above. It ran from the generator in the tow vehicle, through a fuse, to the coach battery. In the picture above, it is about a foot to the left of the water fill pipe, and 6" above the rub rail.

On my '59 it is a three prong plug, with one prong unused.

58BUBBLE · 03-06-2005, 10:10 PM

Yeah, I think that's the same one . I guess my next step is to pull that and test the wires to see exactly where they go. Do most people run new wires through to charge the battery rather than use this old style plug? I want to wire the system to a modern style with a battery which is charged by A/C, or tow vehicle. I am not real familiar with the best way to go. Any ideas?

**markdoane** · 03-07-2005, 07:56 AM

The reason there was a separate charging line for the battery is twofold:

1. The original 6-way connector for the brakes and tail lights did not have a 12V power line. New 7-way connectors do.

2. There were still some positive ground automobiles back then. With a separate charging cord you could rewire it to match the polarity of the tow vehicle.

Most people nowdays switch to a 7-way connector. The drawback is that you can't really get a useful amount of current from the tow vehicle to the battery this way, unless you are on the road several hours and do some careful engineering.

I wasn't long after your trailer was built that Airstream started installing 'Univolts'. These were large, noisy 12 volt converters that could run the 12 volt system and recharge the battery, off of 120Vac feed. Those are usually replaced nowdays with Intellipower converters or some other brand. Doing a forum search on Intellipower or converter will yeild several threads on how to upgrade your system.