[Brad Townsend]

If they were fine before you took the coach in for repair maybe someone created a short. I just replaced all 4 lifeline agm batteries last spring after getting almost 9 years out of my old set. We live off grid 6 months a year with solar panels and used to have a wind turbine that would sometimes under heavy gust put as much as 20 volts into the batteries but only for a short moment. Justin at lifeline said that was ok, because of inconvenience and being less efficient I opted to add another panel and sold the wind turbine.
The batteries will vent somewhat, there is little holes you can see over each cell. I know this because one day while trying to find an air leak with an ultrasound detector and it sounded off when I pointed it at the top of the battery. I trust Lifeline and expect to get more time out of my new set of batteries mainly because I was a green horn learning about solar and proper charging my first 9 years which I think there was some times the batteries were not treated the way they should have been. By the way my old batteries were still in very good condition just not supplying the full amount of amp hours that we depended on each day. The coach still started fine and if the ambient temps were 70+ the house batteries were ok. I estimate by having a Trimetric Battery Monitor that I lost over the the 9 years about 30% capacity from my house batteries. I changed out all 4 batteries because I sometimes merge both banks in cold weather because of the loss in efficiency while cold and when merging both banks the batteries should be the same make and age. If you do not have a Battery monitor there is no way of knowing if your batteries are fully charged. That is why many only get a few years out of your batteries. Trust me I have been doing this for the last 9 years and learned the hard way. There are a couple on this forum that would agree with me because they also have a battery monitor be it a Trimetric or a Bluesky.
If you have a converter you might want to throw it out and get a good 3 stage battery charger or as I did is buy a Magnum inverter with a 125 amp charger built in.
As I said we are off grid 6 months a year and get by without a converter. My old converter was a single stage battery boiler that never properly charged the batteries. While off grid my batteries are charged with a solar charge controller that has the 3 stage charging feature. I believe that all you newelies that are not always plugged in should have a solar panel with a good charge controller and a battery monitor. Because if you are not getting what I got out of your batteries then you have not provided proper charging for your batteries. If you are traveling across country and stop over night at say walmart and use your inverter and draw down your batteries and think your next day of driving will charge the batteries full and stop for another overnight etc. I believe you never really top of your batteries. That is where a solar panel would come in handy.
By the way I paid $625 each for my batteries from Starlight Solar in Yuma az.
One more time, you need a battery monitor and you need to learn how to use it. Lots of money going down the drain otherwise.

Brad