Npdchief07 wrote:
So when not in use I should have the battery disconnect turned to off?
This seems like an easy question to answer, but its not. The best answer I can give is it depends on a number of factors.
Battery disconnects are wired differently in different coaches and depending on whether they were installed by a manufacturer, dealer, or a previous owner in the case of a used coach. It may also depend on where the disconnect is installed. Many, perhaps most, are true battery disconnects in the sense that when you switch them off, they completely disconnect the battery from the coach. However, some manufacturers and owners bypass the disconnect for some circuits.
Going back to your original question,
What does the battery power?
Some things may seem obvious. Lights, electric tongue and stabilizing jacks if so equipped, slide motor(s), awning motor, etc are all "obviously" battery powered. I expect what you really meant was I'm not using these obvious things while its sitting in the driveway, assuming you didn't leave a light on by accident. So why is the battery dead? There are some not so obvious things, especially if you're new to RVing. Every RV is required to have a gas detector installed and this runs anytime the battery is connected. Some have battery powered CO detectors and/or smoke detectors. Traditional RV refrigerators will draw power from the battery if they are set to gas or DC. Newer residential refrigerators have power inverters that convert battery power to AC to run the refrigerator. These will drain multiple fully charged batteries in a matter of hours if left on. Some RVs have smaller inverters for powering a TV or other appliance but these aren't usually installed from the factory. The furnace may draw power if the thermostat is set to furnace. Even if it doesn't need to run, the control board my use power. The thermostat itself on most newer RVs is powered by the battery. Some have clocks powered by the battery.
So, assuming that your disconnect switch disconnects all of these loads, switching it off will prevent those loads from discharging your battery quickly. If just your gas detector is left on your battery or batteries may last a couple of weeks to a couple of months with them switched on. The bad news is that lead acid batteries (the type usually installed in travel trailers from dealer) discharge themselves if left unattended even if they are completely disconnected. At moderate temperatures, lead acid batteries self discharge at a rate of around 5% per month and the self discharge rate increase with higher temperatures.
Your RV has a power converter that charges the batteries when you plug into AC power as well as providing power to the things your battery powers when you're not hooked up to AC. Unfortunately, these converters are notoriously poorly suited to long term battery maintenance. They tend to overcharge batteries when left hooked up indefinitely.
The "best" storage method depends on how long you're going to store the battery. My preferred method of storage is to disconnect the battery from the RV and connect it to a charger that is specifically designed for storage maintenance. I currently have a battery tender brand charger with a quick connect cable that stays attached to my batteries and I just plug the charger in when I put the RV in storage. If you are going to be using the RV regularly, and only storing for a few weeks between uses, then you would probably be fine just switching the disconnect off or leaving the battery disconnect on and plugging the RV into AC.
There are many reasons not to just plug the RV into AC for long term storage. One of the biggest as stated above, is that the converter/charges on almost all RVs will overcharge the batteries, boiling off electrolyte and shortening the batteries life. Another reason to avoid long term unattended AC hookup is the potential for power surge / brownout damage. Unless you have a dedicated RV hookup with a good surge suppressor (which I would recommend), even if you aren't using the appliances in the RV they are subject to power quality issues and lightning damage. There's also no need to run the refrigerator or any other appliances for months at a time when you aren't using them. Finally, many (most) newer RVs have an AC heating element in the water heater. While this should be turned off when not in use, if you forget and leave it on while not connected to a water source any water in the heater, assuming you didn't drain it, will eventually boil and/or evaporate and the heating element will burn out or worse.
