Electrical Questions - trailer vs tow

[Dave Whiting]

As a "newbie", it is not clear to me how the electrical system on the tow vehicle and the batteries on the trailer interact. I have an Escape 19 with an electric tongue jack and 2 6V batteries in series.

Two questions:

1. If the trailer electrical cable to the tow vehicle is connected, when using the electric tongue jack, am I drawing down my trailer batteries or the tow vehicle battery? If the motor was running on the tow vehicle, would the situation change?

2. I have a VIAIR 88P tire inflator that connects directly to the battery (rather than a 12 volt outlet). Even with the 6 ft air hose extension, when the inflator is hooked up to the tow vehicle battery, the air hose will not easily reach the tires of the trailer on the drivers side if the tow vehicle is connected to the trailer. Can I connect the compressor across the trailer batteries instead? Again, should the tow vehicle be running?

Thanks for your expertise!

dave

[padlin]

On my truck there is a relay that opens the line to the truck battery if it is not running. With the truck running the alternator maintains the voltage, depending on the amperage of the jack motor and the size of the wire.

As far as the compressor, hooking to the trailer batteries is my plan if I can't reach with the 300P. Viair has extensions, which I'll get if I can't reach with the existing one.
I think this is the one for the 88P http://viaircorp.com/portable_extensionhose.html

[santacruzer]

I don't believe the electric tongue jack actually draws down your battery all that much, but then I've also never never looked at the specs to see what it DOES draw. I've never had the TV electrically connected to the trailer when I've used it.

[tractors1]

I added an external 12V outlet on each side of the trailer for the 12V compressor, much easier to change to a plug-in connector than futz with battery boxes..................

[Charlie & Lucy]

I have an 18v Ryobi inflator (150 psi max, I think) that uses my drill/driver batteries that I am bringing. They will charge on the 120v when connected to shore power or the inverter plug in the truck cab.
Charlie

[dfandrews]

Originally Posted by Dave Whiting

As a "newbie", it is not clear to me how the electrical system on the tow vehicle and the batteries on the trailer interact. I have an Escape 19 with an electric tongue jack and 2 6V batteries in series.

Two questions:

1. If the trailer electrical cable to the tow vehicle is connected, when using the electric tongue jack, am I drawing down my trailer batteries or the tow vehicle battery? If the motor was running on the tow vehicle, would the situation change?

2. I have a VIAIR 88P tire inflator that connects directly to the battery (rather than a 12 volt outlet). Even with the 6 ft air hose extension, when the inflator is hooked up to the tow vehicle battery, the air hose will not easily reach the tires of the trailer on the drivers side if the tow vehicle is connected to the trailer. Can I connect the compressor across the trailer batteries instead? Again, should the tow vehicle be running?

Thanks for your expertise!

dave

Dave,
Regarding Q#1: most vehicles, but not all, must have the ignition on to power the 12V pin on your 7 pin trailer plug (E.G. my 2011 Honda Pilot). so, if you're plugged in but the tow ignition is off, your jack draws only from your trailer battery(ies).
If you're plugged in and the ignition is on, then you're drawing power from everything in the circuit, which means trailer battery(ies), tow battery, and alternator if the engine is running.

Q#2: the VIAIR 88P manual says max. draw is 20 amps, and the engine must be running (they say it twice). So, with that significant a current draw, you should be connecting directly to the battery (either trailer or tow), and having the engine running is a good safety factor to avoid excessive draining of the battery.

[gbaglo]

I have a couple 12V extension cords that I use so my compressor reaches the tire stem. I just run the cord out the door or out a window to reach the tire. They cost about $2.99 each.

[Dave Whiting]

Thank you Don, you have given me great information. I will have the engine running when I connect my compressor to the trailer batteries.

And it could well be that using my trailer batteries only for the tongue jack is likely not a problem.

dave

[padlin]

Come to think of it, the front legs on my fifth wheel are power jacks, just like your front bumper pull jack. I don't notice any change to the batteries by running them in or out, and there are 2 of them.