qUESTIONS ON CHOOSING AN INVERTER??

[bioVenture]

So I don't have alot of experience with inverters.  I am very knowledgeable about electrical and how it works as I run an automotive electrical repair shop.
Our coach is 24v and from what i have read in the forums here a 24v house bank is the better option while using a vanner for 12v loads.  I can come up with the correct sizing for our coach once we calc what our ac loads are going to consist of. 
My questions is that what can be run properly on an modified sine wave and what shouldnt be run on modified sine.  Do most of you use pure sine converters or is that more of a luxury?? 

What type of power is required for items?

washer\dryer
refrig
laptops?
lcd tv's

Some of your experiences, troubles and recommendations please 

[bevans6]

I chose a Samlex pure sine wave inverter from these guys  http://www.samlexamerica.com/products/inverters.asp

Nice guys, Canadian company in Vancouver does the engineering, manufactured off-shore, Seems a nice product so far.  You are on the right track with 24 volts for the inverter, makes the cabling  a lot easier and you can usually charge off of your bus alternator if you have the DN50.  I chose a 3000 watt inverter, straight inverter with no charger, because I wanted to be able to manage charging separately.  I can't quite remember why now, but that's what I did.  I wired the whole system up through cascaded automatic transfer switches, with the priority to shore power, then generator, then inverter.  That is hard to do if you get an inverter with a built in transfer switch, they tend to put the inverter at the second priority, and I wanted the generator at second.

Pure sine is coming down in price to the point where you can more easily justify it compared to MSW.  Pure sine is better for all induction motors, most chargers, microwaves, and some electronics.  Better means just that - things run cooler, they are more efficient, they don't hum, and chargers don't go stupid.  But most things still work on MSW.  I did not even consider getting a MSW, I went straight to pure sine wave.  The one thing that I needed to run, that justified the whole expense, was the roof top air conditioner.  I wanted to  be able to run it from the inverter and the bus alternator while driving, and that works perfectly.  Everything else runs perfectly too, or course, and my next upgrade is going to be a house style fridge.  I use four 232 AH golf cart batteries, btw.

Brian

[bioVenture]

Thanks Brian!!  Golf cart batteries huh? are you running your house at 24v then?  Four 12v batteries from a 48v cart i'm assuming? How long can u run on your house usefully without a recharge? how big is your roof air unit? 

sorry about bombarding the questions, I love electrical and this is all new to me so I'm in sponge mode!! 

[Sean]

You might have a look at this thread:

http://www.busconversions.com/bbs/index.php?topic=15315.0

-Sean
http://OurOdyssey.BlogSpot.com

[gus]

The bus I'm looking at now has a Freedom 458 inverter/charger (Which I assume is MSW?) hooked up only to charge the batteries/battery.

Since this is a 12v system with only one 8D battery it can't have much output but I thought it might be able to run the Kenmore house type frige which is probably about 6 CF.

I can figure that out but what I don't know is do household refrigerators usually have induction motors?

Thanks

[bevans6]

The thread Sean posted is excellent, and there are others as well.  I find the search feature a little odd, though the one in the tool line in between "forum rules" and "profile" works not bad.

I use four 6V golf cart batteries.  I have a Vanner that I use to pull of all of the normal 12 volt RV house stuff, the dash radio, and stuff like that.  AC use while boondocking is limited to TV, maybe a little microwave, radio at night, almost nothing really.  At this point I have a propane fridge, the planned upgrade is to switch to a house type AC only fridge, and that will become the killer  load on the inverter system.  I only run the AC unit (15Kbtu. 14 amp draw running) when I am on the road, and we have been known to make coffee on the road too.

Brian

[bevans6]

yes, household refrigerators always have induction motors.  I don't know about the Freedom inverter, but it's probably MSW.  You typically (rough rule of thumb and a newish fridge) need a 1,000 watt inverter to handle the starting load easily, and about 250 ah at 12 volts worth of battery to comfortably run the fridge for a day or so without charging.

[bioVenture]

Awesome info guys!  Do most people have their genset able to charge their house batts too or rely on the engines alternator?  I love multiple redundant systems, my wallet on the otherhand disagrees.lol

[bevans6]

Most people just look at the gen set as a source of AC power and everything that uses AC can be run, including the battery charger.  That said, about the most common reason to run the gennie is actually to charge the house batteries.

Brian

[jjrbus]

FWIW  Some accessory we think of as 12V are also available in marine stores in 24V. I used 24V macerator, 24V water pump, 24V rope lights. Also some of my low voltage lighting was 120V AC transformed to 24V DC.  I Just skipped the transformer.
Very little ran off the Vanner. Water heater and furnace are 2 I can think of. I'm sure some of the electrical wizards here could convert those also.
                                                                                    JIm

[bioVenture]

I aim to run as much as possible off 24v, there are sooo many ways of power saving.  http://www.superbrightleds.com is a great source for low wattage lighting, a little pricey but i have used them befor in automotive applications and they have a quality product line.

[Mike in GA]

I was told a long time ago that inverting to 110-120 a/c is much more efficient with a 24 volt inverter than a 12. So while at Luke's shop a number of years ago I had installed a reconditioned 4024 Zantrex with four huge 6 volt Rolls Surette marine batteries.  I also take half the d/c voltage through a Vanner and charge two 6 volt Trojans for the usual lights and pumps, etc.
     I have been very happy with the 4024 inverter, and I think it runs the household refrigerator, computer, etc. with 'cleaner' inverted power. YMMV.
Mike in GA

[bioVenture]

We're not even close to deciding on an inverter yet, but still looking to see what options are available so we can pick something that best suits our needs when the time does come.  I think as far as the house battery bank will be four 12v setup where two are series and then grouped in parallel.  This should provide a faster recharge rate, more uniform charge, and better surge capacity in case of jump starting the engine off the house as well.  Will definitely be using a Vanner for the 12v though, it would be crazy not to. 

[Sean]

...  I think as far as the house battery bank will be four 12v setup where two are series and then grouped in parallel.  ...  Will definitely be using a Vanner for the 12v though, it would be crazy not to.

If you will be using a center-tap for 12v with an equalizer, you'll want to configure your bank as a series connection of parallel groups, rather than a parallel connection of series groups.  Otherwise you'll have multiple "center taps" and you'll only be able to use one of them for your 12v and equalizer connection, thus guaranteeing that that one string will get more cycles than the other(s).

-Sean
http://OurOdyssey.BlogSpot.com

[bioVenture]

yes sean youre right, i seen it that way in my head just twisted the words up on the paper, er keyboard.lol