Originally Posted by loulong
Not sure where you learned your electronics, but there absolutely is a NEED for a fuse at both ends of a connection from a battery in the MH (tow vehicle) to the battery in the toad (towed vehicle), period.
(A diode at the toad end concept accomplishes the same thing protection wise, I just don't like the resultant voltage drop, since the path is already very long and resistive.).
I wouldn't exactly call the TOAD CHARGERS "snake oil", but they are more than is necessary for the job.
The voltage drop across the diode in my setup is about 0.4 V. Seeing that the motorhome batteries are supplying in excess of 13 V the drop is insignificant. I didn't measure any voltage drop from the point where the line starts in the motorhome and the wire end before the diode so I don't get the point of "the path is very long and resistive"
My setup has a fuse at both ends with a diode before the toad battery - total cost was $50 - as I said inexpensive insurance.