Battery Ground in TC

There is no need to have extra grounding since regardless of whether the camper battery is inside the camper, or sitting outside on the bed of the truck, the camper is fully self-contained as far as 12V power inside the camper is concerned. When you choose to get some charging from the engine via the 7-pin plug, both positive and negative supplies come via the 7-pin plug - so no separate ground is required. However a separate ground might improve things - see below

BTW if you want to get a decent charge rate, and better overall charging then you need to direct-connect between the chassis system and the camper system using heavy two-core cable, heavy-duty plug and socket connector and an isolating relay to make sure you can't drain the starter battery when the engine isn't running.

{if you were to direct-ground the camper battery with heavy cable as you originally suggested, this would go part way to improving the charging of the camper battery because you would be reducing the voltage drip in the skinny negative that runs into the 7-pin connector)

Thanks, Everything in the TC works OK. But I wanted to be sure.

When the battery is in the camper it is grounded via the 7 pin but mine is also grounded through the camper tie downs.

I will see if I can explain better. I only have one battery for the truck camper and it sits outside the camper by the wheel well.The only way it is charged is from the 7 pin plug from the truck to the TC and the on board converter.I am thinking the battery should be grounded so that the TC is also grounded. The reason I ask is what do people have when the batteries are inside the TC how is the system grounded. Thanks, when it comes to battery tech the people on here are very smart.

Difficult to answer without knowing how the battery is wired. Since you mentioned a 7-pin plug the camper is probably electrically grounded to the truck when plugged in. But I wouldn't want to count on that ground as the only return to the battery unless the 7-pin plug is the only battery connection to the camper. If you have equal sized leads from the + and - battery terminals feeding into the distribution panel in the camper, you shouldn't need a separate ground from the frame mounted battery to the truck unless you're also using this as a starter battery.

I'm a little confused by your question. The battery is grounded independent of the truck. That's why our campers work off the truck.

Not sure how your wired, IF battery wired both pos/neg from camper relying on 7pin wiring +/-, not needed. (Take mechanical, tie downs etc out of the equation, only wired ground path.) If there is no other ground yes. ground path should @ min equal positive.
If the charge line is directly from truck then ground should also be, going to frame or closer to truck battery better though than thru bed sheet metal.

I would add an additional ground. Larger the better. Maybe a standard battery cable with eyes on both ends.