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mountainsun · 03-29-2012, 11:16 AM

Hey folks-

I picked up my first Airstream, and it did not include any batteries or chargers. This stuff is all new to me, and after reading up on batteries, I think I know which type I'll go with.

My question is this - Is there some sort of schematic that clearly shows all of the components required to power/maintain the 12 volt circuit onboard when not connected to 110v, and whatt's an approximate low and high price range I can anticipate spending ?

After talking to a manufacturer's salesrep, I was told I would need the following:

1 or 2 Deep Cycle Marine batteries
1 Inverter/charger
1 "Shunt"
1 battery monitor

My initial preference is to try and save on the batteries, not going with AGM's, and purchase a decent inverter/charger and other parts, that could be used with AGM batteries after these first batteries die.

If someone has a parts list of everything needed that would be perfect !

Thanks,
Rick

Jammer · 03-29-2012, 11:29 AM

I don't recommend AGMs because I think they are a poor value. Other forum members disagree.

Battery monitors are new to the market and it's not clear how useful they really are. I've asked for opinions and examples from people who have installed them but there has been little feedback as yet. New Airstreams don't come with them and you probably don't need one. As much as I like electrical gadgets I am waiting because of the cost.

Here's a better list:
2 deep cycle wet cell (flooded) batteries, ideally Group 27 if they will fit the space you have, with the shorter Group 24 batteries being an second choice. Allow $80 each if you shop carefully.
1 Charger. I don't recommend an inverter/charger because they are expensive and aren't really that useful. You could consider the Iota DLS-55 at $160 street or the Xantrex Truecharge series at around $400 depending on output power.
Cables. You will probably find that the existing ones are deteriorated or missing. The better auto parts places will custom make these to the exact length you need.

arodriguez60 · 03-29-2012, 11:44 AM

I agree with Jammer. get 2 27 group deepcycle batteries a 3 stage converter(charger). Your unit should already have a voltage meter on the control panel. As for a shunt, it is used in order for a monitor to work. The monitor would be useful if you had solar and wanted to monitor how much power is being used and how much is being put back in. It won't really tell you the condition just what you are using and replacing. The true condition can only be determined with a hydrometer.

Bruce B · 03-29-2012, 11:52 AM

Quote:

Originally Posted by Jammer

....Battery monitors are new to the market and it's not clear how useful they really are. I've asked for opinions and examples from people who have installed them but there has been little feedback as yet......

I have used battery monitors (Ample Power and Xantrex) for 20 years on sailboats. I installed a Bogart Engineering Trimetric monitor on our Airstream just last week. It is the least expensive monitor I have ever used and it appears to work well....
I feel naked without a monitor! Learn to use one and you will love it. Simple questions like "how much battery have we used?" are much easier to answer if you use a monitor thus if you are boondocking you can make an educated guess as to what needs to be done to take care of your battery vis a vis charging. The other thing you quickly begin to learn is the voltage of the bank at various levels of discharge/load. This is nice as you will see a problem as it develops. For example if under "normal" conditions, at the 75% mark, your battery voltage is is typically 12.5 with a light load on it and suddenly you are seeing 12.2 volts it is time to investigate! It is the voltage at % of charge that I watch most closely.
Bruce

TouringDan · 03-29-2012, 01:05 PM

Bruce

Having owned a sail boat would be a great preperation for owning a trailer when using it off the grid- good for you. I have a Volt Minder which just monitors the voltage and only cost about $25. See photo below. I use it to keep track of my battery voltage when boondocking. What additional information does your Bogart Engineering Trimetric monitor provide? How much does it cost? Do you have a photo of it installed?

Thanks, Dan

Bruce B · 03-29-2012, 01:21 PM

Quote:

Originally Posted by TouringDan

Bruce

Having owned a sail boat would be a great preperation for owning a trailer when using it off the grid- good for you. I have a Volt Minder which just monitors the voltage and only cost about $25. See photo below. I use it to keep track of my battery voltage when boondocking. What additional information does your Bogart Engineering Trimetric monitor provide? How much does it cost? Do you have a photo of it installed?

Thanks, Dan

Dan,
The Trimetric was @ $145.00. The newest Xantrex is more than 2 times that number. The Trimetric (and the Xantrex) uses a shunt in the negative battery cable to monitor the amp draw of the 12 volt system at all times. Thus you get a recording of the amps used by the trailer at any time. It records amps out and then amps in when you begin charging again. It uses this information to approximate battery usage. There are papers on the Bogart Engineering site that explain their particular methods for calculating battery “percent of charge” or simply where the battery is in terms of being full. It is admittedly a less than perfect science but it beats the heck out of a volt meter only. Voltage is just one part of a complex equation…..
It does more than this but I tend to use the simple volts and amps used numbers for my decisions.
I’ll take some pictures of the installation this evening and post them here.
Bruce

noreen&sal · 03-29-2012, 03:03 PM

I could very well be wrong, [wouldn't be the 1st time] but all I use is a 40 year old SW voltmeter gauge salvaged from a wrecked boat. Seems to work just fine. Sal.

noreen&sal · 03-29-2012, 03:05 PM

The other time I was wrong was when I thought I was wrong but I was really right. Sal.

Bruce B · 03-29-2012, 03:49 PM

Here you go TouringDan,
The pictures I promised. You will note that the first picture shows .3 amps of charge, this is from the solar panel even though it is a very grey day and almost 5 PM here. The second picture just shows my harness that I have wrapped in spiral protective wrap, I brought it through the bulkhead just above the pocket screw and tied it into the other harnesses running inside the closet. From there it travels down the wall and under the false floor to behind the galley and ultimately to beneath the forward dinette where all the rest of the wiring seems to be gathered. Then it goes through the floor to the front of the trailer where I have the shunt mounted (picture 4). I will enclose the shunt in a service box to protect it from the elements (later). Picture 3 just shows all of the “stuff” on that bulkhead. I just lined it up with what was already there!
Bruce

Bruce B · 03-29-2012, 03:51 PM

Quote:

Originally Posted by noreen

I could very well be wrong, [wouldn't be the 1st time] but all I use is a 40 year old SW voltmeter gauge salvaged from a wrecked boat. Seems to work just fine. Sal.

Sal,
I'm sure it works exactly like it was designed to work, it reports voltage! Nothing wrong with that.....
Bruce