[asphaltgambler]

I don't agree with pulling batteries unless for long term storage ( more than a year) and even that would only apply to the RV.

Modern vehicles, especially Mercedes, BMW, Audi have long term settings that are kept in memory. Further many have the battery 'registered' to the car - meaning the vehicle's electronic memory keeps track of how long the battery has been installed and adjusts amp / voltage over time according the remaining useful life.

I have seen way more harm than good by a well intended battery removal. If you did not know, prior to removing a battery - the system modules need time to 'go to sleep'. Meaning that with the trunk open, you have to manually close the trunk latch ( there's a micro switch ), turn everything off, lock the car and then give it at least 20 minutes.

Even with this procedure you still can create a monster of a problem. 1 of which when you reinstall the battery and the modules 'wake-up' some may not communicate with each other or other issues arise that only can be corrected with OE or OE compatible programming software.

RV's are on the other end of the spectrum where the various add-on accessories create a fairly large draw ( excess of 70 Ma) on the batteries at rest. Most RV's I've seen have multiple stages of wiring and accessories installed many of which are after the initial build where it is just plain sloppy. As in: the default is to tap into the 'Bat' circuit when all else fails to find the appropriate 'Key-On' supply feed.

Believe it or not, short battery life is with the loss of electrons is through the case. Better batteries have thicker cases. 2nd largest is a dirty battery top.

I really like and use Interstate batteries so you have at least two of those I see. Keep the cases and top clean, keep your posts / terminals clean; that's it.

In your cars I would not recommend any 'protectant' as they live inside the trunk or rear floor. Unless your RV has a 'sealed' battery compartment I would recommend an oil based protectant lightly sprayed onto the terminals to avoid corrosion. One product that I use is NCP2 Battery Corrosion Preventative.