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myoung · 03-16-2006, 10:33 PM

We are looking to add an inverter to convert 12 volt to 110 volt power so that we can run two devices: a small drip coffee maker and a laptop computer. What size inverter should we consider? What is the best way to wire it in permanently? Alternatively, should we just plug it into one of the 3 12 volt outlets when needed? Would the factory have installed an inverter and, if so, where and what size? Is it feasible or desireable to wire the inverter within the existing electrical distribution system so that all the electrical outlets could be active via the inverter or should devices be plugged into dedicated outlets limited to the inverter circuitry?

Lots of questions. I'm not well-versed in things electrical as you can tell, but I hope these questions make sense.

I think we have plenty of battery capacity. We have the solar collector that feeds two glassmat batteries.

SilverRanger · 03-17-2006, 12:22 AM

The size of the inverter would depend on the total wattage of the devices you intend to operate. I would imagine a drip coffee maker would take a lot of power to operate. You may want to consider one of the many 12 volt coffee makers available. We make good coffee by heating the water on the gas burner and using a coffee press. We do this at home too, and haven't used a drip type coffee maker in years (but that's a whole other thread).

I have a 400 watt inverter that I use to power my laptop and LCD television, and it is more than adequate. I just use one of the existing 12v outlets for that. I have read on one of the numerous inverter threads on the forum (search "voltage inverter") that, if you are going to use a high watt inverter, you should wire it as close to the batteries as possible to reduce voltage loss. A nice feature on many inverters to consider is an automatic shut down when the battery voltage goes below a certain level.

lewster · 03-17-2006, 05:52 AM

There are tons of inverters on the market now. IMHO, some of the best are made by Xantrex. Their products are in just about every large MoHo that I work on. I agree with the Ranger, look at the data plates on the appliances that you want to run, add up the watts, and go a little oversize, say +20% on the inverter capacity. Some will have an overload feature that lets you overdraw that stated capacity for things like starting motors and the like.

If it's under 250 watts, you can usually jut use a 12V plug-in. Anything higher should be hard-wired to the battery or oher available 12V source. DC is very susceptible to voltage drop so your conection wires should be as short as possible and large in guage.The instructions usually give you footage and wire sizes.

myoung · 03-17-2006, 06:13 AM

I'm starting to learn the rules. I've been reading a bit and find that the limiting factor is the coffee maker which consumes about 800-900 watts. So, for one-half hour of use that device would consume about 45-50 amp hours.

Now what I need to know is how much battery capacity we have. Ours is a new Airstream with solar panels so the standard batteries have been replaced with something called Glassmatt (sp?) batteries. I have not been able to find the amp-hour rating of these batteries on the Airstream web site or the site of any Airstream dealer.

Our trailer is quite a distance away in the storage yard, so I someone could advise me as to the capacity of these batteries, I would appreciate the help and then I could go on to the next step. Thanks in advance.

SilverRanger · 03-17-2006, 07:57 AM

Mike
If your batteries were factory installed by Airstream, they are probably made by Lifeline. Here is a link to their RV battery specifications page. I don't know which model of battery you have, and I'm on the road right now or I'd look at mine. I believe mine are the GPL-24T or GPL-27T.

http://tinyurl.com/ffp8p