If you want to use the 2nd battery for starting/winching as well as fridge etc then a VSR with 2 B&S cable is the way to go - simple, cheap and ultra reliable.
If the 2nd battery is only for low power use such as a fridge and you don't want to run large cables then you can consider a DC DC Charger like the Ctek or BCDC.
DC/DC chargers are a low current device and won't back feed unless additional gear is installed and then you need the 2 B&S anyway.
IMHO DC/DC chargers are of limited value in a vehicle unless you are running AGM or Calcium batteries or restricted in cable size.
Reply With Quote