Our coach came with a
Battery Minder which worked fine while you were on shore power but tended to discharge the batteries when not connected AND it would only provide 1 amp of charge, not even enough to cover the radio playing! In 2010 we replaced it with the Trik-L-Start by
LSL Products and haven't had a problem since.
LSL Products came out with its 15 amp AMP-L-Start later and would now be the preferred unit. A few years later Xantrex came out with the Echo Charger which is essentially the same as the AMP-L-Start but costs about $50 more. I have no experience with the Echo and haven't heard much about it but I do know the AMP-L-Start will do the job and it's an install then forget about it solution and the install is very easy.