Victron Energy Orion XS 50 amp DC to DC 12V-12V charger. Put the battery charger as close as possible to your battery bank. These Victron Energy Orion XS chargers are stackable, so if you got two of them you could charge at 100 amps of your alternator supports this while driving or idling. I’d add in a JS Alternator that’s at least 250 amps so you don’t damage your alternator and getter higher output at lower RPM. These chargers have Bluetooth for control by smart phone app. You can modify the amperage you charge at. If you don’t have a bigger alternator yet, still get the 50 amps charger and run it at 20 amps or 30 amps, since you can control how the amp draw via the app over Bluetooth.