RV 12V power wire

[robaer]

Those are great posts. The doc attachment was perfect. I think I will use the same connection points as Florida Native did. Cant wait to pop the panels now. Thanks so much for restoring those posts because there really is a lack of this detail on the interwebs and I expect there will be more "diy trailer guys" doing this. Super helpful to have them.

[RidgeRunnr]

This is a GREAT thread! The only thing I did not see addressed was the capacity of the '04 Sienna XLE alternator. The RV place I had hook up my 7-pin connector system would not run a 12V line for the battery/fridge system, as he said the alternator did not have enough Amp output. I only pull a Coleman/Fleetwood pop-up with electric brakes. Thanks.

[brian_bp]

The RV place I had hook up my 7-pin connector system would not run a 12V line for the battery/fridge system, as he said the alternator did not have enough Amp output.

I suppose if you are going to try welding with the 12V power line, then you shouldn't do it with a Sienna. On the other hand, it works fine to charge an RV trailer battery.

What did these people dictate was the minimum required alternator capacity? How much current did they say the trailer would use? My guess is that they also insist that only pickup trucks and large SUVs should tow, and that the Sienna can barely handle the pop-up. I don't put much faith in random retail "experts", but in this case it is surprising that they would pass up the opportunity to make more money by selling another service... or did they charge the same for the wiring without bothering to do the charge/power line?

In a conventional RV installation, this circuit connects the tow vehicle's charging system to the trailer's battery, not just directly to some unknown load. This trailer charge circuit only needs to keep up with the average of power used by the trailer (or less, since if the charging does not keep up the trailer battery just runs down), not the peak power used if lots of stuff is turned on in the trailer.

Also, the circuit must be protected by a fuse or circuit breaker (no larger than that appropriate for the wiring), which sets an upper limit on how much current might be drawn. Mine is 30 amps, but it is an auto-reset circuit breaker, so if it is tripping and resetting I wouldn't know, so I really don't know how much current goes to the trailer battery.

[tcp]

All that plus the fact that line losses in wire running to the trailer have a bit of a self-regulating effect. The more current that is flowing, the more loss in the cabling which reduces the voltage at the trailer end and therefore charges the battery in the RV at a lower rate. The chances of ever seeing 30 amps in your average 10gauge or even 8 gauge wire over the 30-40 feet (remember current has to flow back from the trailer as well, it's an out and back journey) is remote unless there is very close to a short on the other end.

Generally the "charge" wire is more a maintenance wire for the fridge/monoxide detector and doesn't add more than a surface charge to the RV battery while driving. True charging of the RV battery requires AC/converter/batt charger to actually fill it.

The RV place I had hook up my 7-pin connector system would not run a 12V line for the battery/fridge system, as he said the alternator did not have enough Amp output.

I suppose if you are going to try welding with the 12V power line, then you shouldn't do it with a Sienna. On the other hand, it works fine to charge an RV trailer battery.

What did these people dictate was the minimum required alternator capacity? How much current did they say the trailer would use? My guess is that they also insist that only pickup trucks and large SUVs should tow, and that the Sienna can barely handle the pop-up. I don't put much faith in random retail "experts", but in this case it is surprising that they would pass up the opportunity to make more money by selling another service... or did they charge the same for the wiring without bothering to do the charge/power line?

In a conventional RV installation, this circuit connects the tow vehicle's charging system to the trailer's battery, not just directly to some unknown load. This trailer charge circuit only needs to keep up with the average of power used by the trailer (or less, since if the charging does not keep up the trailer battery just runs down), not the peak power used if lots of stuff is turned on in the trailer.

Also, the circuit must be protected by a fuse or circuit breaker (no larger than that appropriate for the wiring), which sets an upper limit on how much current might be drawn. Mine is 30 amps, but it is an auto-reset circuit breaker, so if it is tripping and resetting I wouldn't know, so I really don't know how much current goes to the trailer battery.