Re: Coach Batteries
While it is quite possible that your battery disconnect isn't disconnecting quite everything, none the less they should stay up much longer than that if the disconnect is open. You can easily find out for sure by after you return from your next trip you can lift the negative cable from it's battery post. Then you wil know that the batteries are isolated. I suggest that you then check the resting voltage of the batteries to know just where they are. They should be at least 12.5V if in reasonably good condition. Then let them sit for a week or so and see what the voltage is. It should not drop more than .1 to .2V per week. You can also test by using a battery charger to bring the batteries to full charge. If you do this, lift the negative cable from the batteries first, then charge the batteries completely. Allow them to "rest" for at least two hours and then get an accurate voltage reading. If they are in good condition the voltage should be at least 12.5V at that time. From there you can see how quickly the voltage falls off. Below is a chart showing both the voltage and the hydrometer readings a battery should have at the various charge levels.
Temperature: 67 degrees Fahrenheit
Percent Hydrometer Unloaded
charge reading voltage
100 1.262 12.61
75 1.207 12.28
50 1.157 11.98
25 1.117 11.74
0 1.097 11.62