Originally Posted by Seann45
Ummmmm if you plug your umbilical cord into the tow vehicle it is the same as using jumper cables.....snip
I 'believe' that most standard automotive alternators can put out a maximum of around 60 AMPS, but the voltage regulator controls the amount going out based on the TV's electrical system demand..., but is minimal through the 7-pin connector. It's been my understanding that jumping off the TV's battery will allow more AMPS to flow (although regulated) in lieu of a 7-pin connector when being utilized (please note: OP presently has a 4-pin connector, stating it doesn't provide any charging capability to his PUP).
I would agree that if charging is only available from a TV, the 7-pin connector would be more convenient (simple hook-up), but using the jumper method has it's benefits when utilized correctly.
In any case, I would consider other alternatives (some suggested earlier) if I found myself relying to often on my TV to keep my RV battery charged while dry camping.