Coach Electrical Systems

[eagle19952]

with a 24v house system and a 24v/110v inverter, using 110v LED lighting you will be far better off than trying to "have 12v interior systems"

at least that's what i'd do.

I would also have one combined battery bank. which I do.

[eagle19952]

http://jdfinley.com/electrical-system-design/

are you boondocking...
is solar in the cards....
the example on that link is over engineered. And unnecessarily complicated...
I.M.O.

[PNWorBUST72]

We want to boondock but the overall electrical design/needs of the bus will help dictate that at first.  I dont have 10k to spend in batteries and panels.

Solar is a for sure yes, next phase of the build.

Electrical, in case its not obvious, is still hard for me to follow sometimes, but I am trying.  Thanks to all for your help. 

[scanzel]

In my conversion I have 8 agm batteries with a Magnum 4024 inverter, in my interior I have some ac items, refrigerator, 3 built in electric wall heaters, microwave, a full gas stove with oven, 2 Samsung smart TV's, Splendid combo washer dryer, air compressor, electric 20gal water heater. So you can see some items will need 120/220 ac. Except for 2 ac lights that my wife really wanted all my other lighting is either 12 or 24v dc. My 12v dc tap if used with a Vanner equalizer. For charging the batteries up it is shore power or generator, solar someday. Have had no problem so far keeping the refrigerator running while driving to destinations off the invertor. My 2 ac lights have led bulbs so the ac draw is less. 12V items are easy the find 24V a little harder but if you search you can usually find something. I didn't want to tap too much 12v so I tried to find more 24v items.

[Oonrahnjay]

... I am looking at this and it seem 24v on BOTH sides is the best option: http://jdfinley.com/electrical-system-design/

     Yes, but ...   You say "lights and charging ports, etc."  It harder to find those kinds of items in 24V.  Lights are available but a much smaller range of wattage, color, etc.  If you have 12V, you can use 12V "thimble" chargers for USB chargers but I don't think I've seen such a thing in 24V.  I think that for interior devices, you need either 12V or 120V. 
     I agree with Eagle's comments, too.  Keep it simple, but if you want real electrical capability, you will need batteries and an inverter. 

[Geoff]

It might help to change your terms:. The batteries for the starter in a bus conversion are called the "start" batteries, the batteries for the RV stuff are called the "house" batteries.  Sometimes the batteries are both. 

For my conversion, I kept the 24v starter, and made a 12v RV system.  Two alternators, 12v and 24v. Two 12v batteries in series for starting, four golf cart batteries for the 12v system. Most of the MC 7-8 run two alternators like I do.

[richard5933]

For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.

My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.

I see lots of people going with the residential fridge units, so I assume that I'm missing something. 

[Oonrahnjay]

For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.

My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.

I see lots of people going with the residential fridge units, so I assume that I'm missing something. 

     Calculate in watts and you'll see what you're missing.

[eagle19952]

For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.

My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.

I see lots of people going with the residential fridge units, so I assume that I'm missing something. 

since when is a conversion efficient ? isn't that a classic oxymoron ?

if you aren't boondocking then a good inverter has a pass thru that does not eat battery wattage.
the OP needs to express or determine his intent.
my need for inverter supported output is from point a to point b or short term, (say 7-10 days or less off the pole. I am all electric. no propane).

it matters, and we are all just speculating.

[buswarrior]

A regular house refrigerator costs to buy versus a DC or propane refrigerator costs to buy...?

I can buy the batteries necessary and then some, with the difference.

As noted, efficiency in a bus conversion???

Only of the cheque book?

And poorly on that too...

happy coaching!
buswarrior

[bobofthenorth]

For those recommending a 120v system for most appliances (which will be run through an inverter), I don't understand how it's more efficient.

My 12v DC fridge draws about 2 amps DC. An AC fridge, even one that draws only 2 amps, will actually draw much more from the batteries since making 2 amps AC will require 20+ amps DC.

I see lots of people going with the residential fridge units, so I assume that I'm missing something. 

Not a chance this is accurate if its actually running on DC.  Maybe it draws 2 amps @ 12 volts while running on propane but there's zero chance it draws that running on 12 volts. 

Absorption fridges are notoriously inefficient so that may make a case for inverting up to 110 but the other option would be a 12 volt compressor fridge.  Either way, its going to draw significantly more than 2 amps @ 12 volts while its running.

[richard5933]

I am taking about 12v compressor units, not absorption. I don't have specifics on my fridge since it's older, but I've seen stats on new units between 2-5 amps depending on size. Even if it's twice that, it is still less than a residential fridge would pull from the batteries through the inverter.

[Geoff]

I like my beer COLD.  RV refers suck-- not cold enough, and ice cream isn't frozen. Plus you have to vent them out the roof, cost too much new, and are too small.  I never heard of 12v RV reefers without also having propane (I know, Summit, but are they for boats?).

[chessie4905]

He probably has this one or an older version.

http://www.thetford.com/product/de-0061ev-0061/

[Geoff]

Well, eBay had two. $1300.+, and 1800.+.  7 cu ft.

I paid $299 for my stainless steel Sanyo and it is 10.3 cu ft.  They are just hard to find in SS.  Costco is the place to buy them when available, I've seen prices double than that on line.