Coach Batteries Died: How long does a charge last?

[Seon]

Went dry camping for two days in my '84 Chiefain. House batteries died on the second night. A day before I departed I replaced one of the two deep cycle batteries, fully charged both existing and new one. The only major draw was the heater blower at night. First night was fine but  awoke at 3 am this morning freezing and  discovered the batteries were drained.
So how long does the charge on the batteries normally last?  Hm?

[Froggy1936]

Till there dead !!  But really the furnace blower and furnace controls pull a lot of amps.  I would estimate 4 hrs to 6 hrs (cycling) from fully charged (2 battery's)  till dead, at 40 degrees outside and thermostat set for 70 degrees inside.  To run a furnace and a few lights for a couple days you will need to have a battery charger going constantly.  Also, the fridge on propane operation uses coach battery power for the controls + the water pump uses some.

[Seon]

You hit the nail right on the head  . It was 36 degrees each night and the thermostat was set at 70 degrees. The batteries read 1.2v when i checked the next morning...after I thawed out  :)rotflmao.

I guess I'll get the Mr. Buddy heater going the next time I dry camp...which is probably sometimes this week.

Thanks

[DaveVA78Chieftain]

This is one of the best informational pages for RV's.  A bit long, but good reading to grasp an understanding of this subject.
http://bart.ccis.com/home/mnemeth/12volt/12volta.htm

Further Reading:
Mecahnics 101 section (Members Area) of this site.

Progressive Dynamics: The company who made our orginal converters
http://www.progressivedyn.com/battery_basics.html
http://www.progressivedyn.com/battery_manage_101.html

Poop Sheets:
http://www.phrannie.org/phredex.html
http://www.phrannie.org/phrends.html
The book Managing 12 Volts. How to Upgrade, Operate and Troubleshoot 12 Electrical Systems. By Harold Barre is one of the best books out there.

There is a whole bunch more information out there on the net.
You have to know:
What the battery is capable of.
How you can damage it (running it down to 1vDC like you did can kill the battery).
Why you should not discharge your battery below 50% (12.06VDC)
What are the different types of charging methods.
What size battery bank do you need for what it is you want to do.
What limitations apply to the engine alternator charging system.
etc., etc., etc.

Dave