I totally agree with the RV Wizard on that we kill our own batteries but in Jims case the crime maybe just old age or happened before he bought the coach.
Jim, if you have never put new motor batteries in the coach since you have owned it and it is 8-9 years old means that it probably either has the original batteries in it or the batteries are half that age. Most of the time there is nothing wrong with the charging system and it is just the battery(s) is old or the posts are corroded or just dirty inside and you can't see it. My recommendation is to pull all the batteries out of the coach and take them in somewhere and get them checked under load. Sears can do that for you and so can NAPA or many other car places. When they check the batteries they can probably tell you the date the batteries were made. Then you can check the warranty on the batteries. If the batteries have exceded the warranty time then replace them. If they check good and still within the warranty time then get a battery terminal brush and clean the inside of the cables ends and the battery terminals, check the water and put them back in and see if what happens.
If thes battery(s) is close to the end of its life, or it checks weak, or you have never replaced them and there is no date then replace them. A bad battery can just take the fun out of it and can end up costing you more than the battery replacement if you get stuck somewhere and have to get help.
Also, it helps to get one of those small battery charger maintainers for when the MH is stored. I always have one hooked up to my batteries. I have a small jumper wire with alligator clips on it and hook both the motor and house batteries together in run them off one charger.
I use the Autometer 9201 charger and have been real happy with it