Not going to speak to the battery charging, please search battery charging to get about a weeks worth of reading...
For the air systems, the suspension or air bags have a ride height valve that controls air flow into and out of the air bag.
Once at ride height, and if not moving the valve is "off", while driving the valve is constantly changing due to bumps in the road, this is why when parked you seldom hear the dehydrator dump, but then it dumps often while traveling.
Anyway, if the valves, bags and everything else is not leaking then the bags stay full, most will seep over time and the chassis will swuat down an a day or two.
Depending on your chassis, you likely have one valve in the center of the front axle and one at each rear wheel.
With the front only one valve, easy, in back if one leals a little then it shifts the opposite side causing it to open and drop the suspension down.
Whichever air system that drives the air bags gets depleated while the other one(s) retain their air as they are all seperated by check valves for safety.
On batteries, if they are taking a higher charge for a longer period of time then either the charging voltage is now higher or the batteries more discharged.
They will take a good amount of charge current while in bulk charge, then the current will drop off in absorbion phase, then when the voltage is correct it can be switched to float.
A constant voltage charger set to 13,5 volts will charge the battery correctly, but slower than others, in your case the battery is not even close to being charged properly and over time may loose some capacity, it will need a deep charge over a few days to insure fully charged, that will need a proper charger if left unattended.
Solar would be good investment for floating the batteries while in storage, current needs are minor if charged before storing.
Tony & Lori
1989 Country Coach Savannah SE