Inverters

[BikerBilly]

Ok,
I just spent an obscene amount of money getting all the av stuff and tvs working in my fred and having a dish network setup put in. Now.....I want to be able to have dvd player and tv in the bedroom work while in motion so my angels can watch a movie. Since my fred is kinda entry level he has no inverter so no 110 without shore power or generator. Soooooo..what smaller wattage point of use inverter would you recommend? The 12v plug ins are only rated for 200 watts, or so I've been told and the tv is a looong way from my batteries. Thanks
Billy

[Chuck v]

Billy,

Are you sure that the TV in your bedroom is not capable of being run on DC already? The bedroom TV in my 2007 TourMaster was DC powered at all times (it no longer is, as it was replaced with a much better HDTV, but that is another discussion...)

If you use an inverter that is rated at a CONTINUOUS power of at least sum of the peak wattage shown on each of the nameplates of the TV and DVD players (plus a game console, if that is a future consideration) you should be fine. Just be aware that the input to a 12 volt inverter needs over TEN TIMES the current of the AC output (because the voltage steps up by a factor of ten, and the watts in will be a bit more that the watts out due to losses in the conversion.)

For example -- if nominally the HDTV takes as much as 250 watts, the DVD takes 40 watts and a game console takes 60 watts, the total is 350. If the inverter is the typical 80% efficient, then the input power to the inverter needs to be around 437 watts and that means that the DC wiring to the inverter from the battery will be carrying about 36 amps. Obviously, you will want to locate the inverter close to the batteries and use large gauge wire in the supply side to the inverter. In actual use the appliances may draw considerably less than the nameplate power, but you still have to plan for the maximums... Do a proper job of permanently wiring any high current DC device such as an inverter -- keep it safe!

Now for some ACTUAL power ratings for some energy efficient newer consumer electronics appliances: The Sharp LC 20SH7U is a 20 inch TV that has an "operational power' rating of only 60 watts (newest models are quite a bit less power hungry as you can see!) and a Blu-Ray player such as the Samsung BD-C5500 consumes 14 watts, so even if the peaks are several times these averages you may be able to live within a 200 watt rating of a plug in type of brick inverter. Just be aware that sensitive electronics prefer pure sine wave AC power best, so look for that capability in any inverter you are choosing.

Chuck

[BikerBilly]

Thanks Chuck,
I have been doing some study and have decided the girls are just going to have to make do with their portable 9" dvd player when we are on the road. For me the whole coach inverter would be nice, but not worth the trouble or cost to install. I have bought a 40w solar panel and controller to act as a supplemental battery charger... just in case we end up off grid more often than I expect. :)