Don't get some of the posts about the fear of batteries dying while on the road, so change them out before leaving on a trip, whether they seem weak or not, spending a bundle to get the very best...etc...etc. With the chassis battery, same thing and no problem with having the built in jumper network with a push of a button.
We left on a US tour in 09 and I pretty much knew that my original coach batteries had seen better days. Didn't do any real dry camping for the first 4000 miles and then when we did, the batteries wouldn't sustain even one day with the inverter supplying a few things. So, while going through as town in WA the next day, we stopped at a Sam's club for lunch. Did so and then while DW was shopping, I changed out the batteries. Shopping cart with the old and back again with the new with maybe an extra hour involved and mostly with waiting. Still running those batteries, along with another tour on the road this past summer and they should be good for some time to come. To each his own, I guess and we're not one for inventing ways to spend money, as that seems to take care of itself.