Battery Usage

My Wife & I just traded our 99 coleman for a 2000, 3023. We will be taking it out for the 1st time  to a site this weekend that does not have hookups.  The unit has 2 batteries. The Temp at night will be in the 40s.  If we run the furnace some throughout the night, and conserve on the lights, approx how long should the batteries last? Do you think they will last 4 nights?    

One battery lasts us 3 days for dry camping and that includes running the Tv.  I have a small generator to recharge the battery after that.  Gary K :

How long you get from the batteries is a function of the reserve capacity of the batteries and the amount of amp draw you use.

If you have 2 six volt golf car batteries, then you have about 200 amp hour reserve. If you have two group 27 batteries, you get the same. If you have two group 24 batteries, you'll get about 175 amp hours reserve.

Anyway, If you remember to run your refridg on gas, you'll be able to go longer. Remember to use your thermostat and keep the trailer at the MINIMUM comfortable temperature for you, so once it heats up, the fan doesn't need to cycle as often. It's the fan that eats the power.

I would estimate you'll probably draw 20 to 25 amp hours a day - assuming you leave your heater on during the day.

So if you have a 200 amp hour reserve in your battery bank, then you'd be good for 8 days. You'd need to draw over 67 amp hours to only last 3 days with a 200 amp hour reserve battery pack. You'd get 7 days out of the 175 amp hour reserve battery pack.

Hope that helps.

Hi all -
In my research on RV electrical systems, I learned that while our batteries have an amp-hour rating which represents the current they could potentially supply for a length of time, there are several factors to keep in mind.  

First, the amp-hour ratings are determined in several ways, one of the most common being a rating based on how long the battery could supply a 1 amp current.  This isn't very practical, since many single light bulbs draw 1.5 amps, and a furnace fan anywhere from 4-8 amps!  The performance of the battery may be drastically different at a 4.0 amp draw versus the rated 1.0 amp.

Also, and perhaps more important, is the fact that depleting your batteries much below 50% of their capacity on a regular basis can dramatically shorten the life of the batteries.  Deep cycle (marine/RV) batteries can be discharged up to 80%, but doing so more than occasionally has been blamed for ruining batteries too quickly.

For lots of information on these topics, I recommend a book called RV Electrical Systems by Bill & Jan Moeller.  The book includes a simple formula for calculating boondocking time & a table of typical amperage draws of RV equipment.

Happy camping!

You are of course correct. That's why I'm having solar panels installed today, so that I can dry camp without worrying about whether I have enough electricity.

Gregg

As a Newbe to the TM. I appreciate your comments and it sounds like AMP conservation is the key.  Thanks for your replies.
Rod