I have a charger on my Optima in the Corvette right now. It sits for 2 weeks sometimes, so I top it off occasionally. My charger hits at about 6 amps, then reduces to 1-2 amps over about 3-4 hours, as the charge builds. No problems doing it this way so far, the Optima is about 5 years old and taking the abuse well so far. I have to run a gel type cause GM put the main computer directly under the battery. An acid leak fries the whole system - ask me how I know!

For the MB, I find it a lot cheaper to run a big huge AutoZone battery with lids for adding water occasionally. Water level is the key to battery life in
Texas. I'm on my 3rd battery on an 18 year-old car; no complaints.

DG