Charles Marine makes some very high end marine chargers. I put one in my boat this summer. 50 amps, as it happens, cost $675. msrp was $1200, but the boatyard owner cut me a deal.

They make 2 lines. One maxed out at 50 amps and the second line begins at 50 amps. I got one from the line that starts at 50 amps. Defender had the one from the line that maxes out at 50 amps for about $125 less, but I figured this one would be beefier. As much as I like Defender, I had to buy local, given the opportunity and even close to a matching price.

It handles three banks independently, so I am very pleased. Getting that unit saved replacing the combiner ($200) which was between the engine and windlass bank and got fried during one of those Oh Shit moments... sigh.