First, LA batteries DO NOT like to be in a discharged
condition.  This will shorten their life considerably.

Modern RV have various items that continue to draw power
even when you got everything turned off.  They can and do
pull a battery down.  You can either make sure batteries are
disconnect from the chassis and coach to insure no current
draw or as you mentioned, install a solar panel.

Parasitic draws can be up to about .5A for some rigs.  If
you go with a solar panel, it will have to be large enough
to replace those parasitics draws with-in the number of hrs
the panel can provide the replacement energy.

Don't know where you are, the storage conditions or related
issues but it the panel can only provide power for say 6
hrs, it will have to be at a high enough rate to cover those
other 18hrs it's not providing power.  Don't forget cloudy
days when the panel won't produce as much power.

Mickey

Lewis;

Note that not all MH's charge the engine battery when plugged into shore
power. If you do setup a solar system to charge your house battery, then it
is possible to charge the engine battery from the house battery using an
additional electrical device. Here are two I have found. I have not tried
either one, so I can't vouch for how well they work.

James
----------------------------------------
http://www.lslproducts.com/TLSPage.html
This is a unique charger that charges the engine battery from the house
battery (assuming the house battery is being charged by the converter when
plugged into shore power). It only requires three wires to be connected
inside the engine compartment. Also contains a diode to prevent the engine
battery from being discharged into the house battery. $48.95

--------------------------------

10/23/2006 11:34 AM

Here is a similar device

http://www.intellitec.com/PDF/5300362.100.pdf

Twice now, when we attempted to start our RV both batteries were completely
dead.
 Last November we replaced BOTH at a cost of over $250.00 (the household is
a huge deep cycle battery that is easily installed using a forklift from the
bottom of the front). Now both batteries a dead.<<

Like someone has already mentioned........
There is no reason a battery should go dead in a month without an electrical
draw somewhere.
Unhook the negative cables from each battery and you should be fine.

Scott,

You gave us no hint what the year this vehicle was built, and that may
give a better idea what equipment might have been installed.

Mickey is right on a number of counts, but I would like to add some
things and clarify others.

Yes, you should have a charging system for each battery.  If you can
shutdown all the blind parsitic loads, then a good battery can sit for
months without leakage depleting the charge significantly.  Boats that
do not have an automatic electric bilge pumps to this all the time.

The start battery of any modern vehicle has a continues load that
supports the onboard processors for the engine (at least), transmission,
body and safety systems.  If the vehicle is fuel injected, it has an ECU
(Engine Control Unit = Processor) somewhere.  If the engine processor
losses its power for an extended period, you MAY have some drivability
issues on restart.   If the radio can lose its memory when power down,
them it is a load, also.

What is killing the house battery?   Well, it could be, a radio like
above, a CO monitior, an electronic thermstat, an inverter/charger, the
potable water pump, anything that you don't pay attention to, or (like
so many cars with hood and truck lights) an automatic light hidden
somewhere that is not shutting off when it should.

As to solar panels.  It does not take very much to make up for both the
battery leakage and the load that I have just mentioned - of course, the
more you can eliminate the better.   Buy a small one to start.  I live
in Michigan, and a panel less than a square foot will keep my start
battery alive forever - even in winter.

If the unit has a diode based charging isolator, you can hook the panel
on the alternator side of that and lose some charging rate and you will
only need one larger panel.

I hope this is some of the answer you needed.

Matt Colie

Sorry. We are located in the Central Coast of California.

Our RV is a 1978 Bounder. I do appreciate all your info and responses. Once
charged I can disconnect the neg. cables and/or install a solar "trickle".

The problem now is getting the two batteries charged. I can pull out the
engine battery very easily, but the household battery is huge. As I
mentioned, when our local battery outlet has to remove or install the
household they use a forklift. Drop the household down from infront of the
engine onto the tonges of the forklift and back it out. I have no forklift
at the storage site and again NO electrical outlet (shore power).

If I charge the engine battery, and start the Generator, will this recharge
the Household battery over time?

Thanks,
  Scott

Not specific on your requirements but much about how to maintain a
battery and how to get long life:

http://www.batteryfaq.org

Our '99 Winnie came equipped with a 15W solar panel; and it's been
doing just fine up here in the frosty north where the solar panel is
often covered with snow for weeks at a time.

For this system to work, the house battery-disconnect MUST be set in
disconnect-mode to eliminate parasitic drains from stuff like propane
detector, fridge, thermostat, etc.

You didn't mention what kind of rig you have. Most Fords can sit
unattended for months at time without needing attention. Chevs will
generally drain your battery in short order; so if you have a Chev, a
jumper from the coach to chassis battery *might* work, but it's also
possible that you may need to disconnect the chassis battery on a
Chev.