Look...
MANUAL CHARGERS ONLY were successfully used for like nine decades with lead acid batteries. Note the word successfully. It has meaning.
Maybe our ancestors were more intelligent than some folks posting on this forum. Flick your wrist on the steering wheel on a 2-lane road and a grater-like Peterbilt radiator grill may fricassee it's way back to your rear axle. Or step out your door wrong and end up in a body cast for six-months.
We all wish and pray that today's RV'er does not have fourteen too many brewskies and boil batteries to explosion. Jeez have mental powers actually degenerated to the point where folks need keepers? "Hey Harry, don't lick the receptacle!"
God forbid. Ten tons hurtling down the road powered by a skull enclosing 25" of vacuum.`
I give up...