Disconnect electrical cable between TV and trailer when park

[ron]

If we stop for several hours when towing, should I be disconnecting the 7 pin cable between the tv and trailer?  Generally we are using the refrigerator on gas while moving.  I was wondering at what point this would begin to drain my tv battery if any.  Thank you.

[tinkeringtechie]

[quote source="/post/3527/thread" timestamp="1410540714" author="@ron"]If we stop for several hours when towing, should I be disconnecting the 7 pin cable between the tv and trailer?  Generally we are using the refrigerator on gas while moving.  I was wondering at what point this would begin to drain my tv battery if any.  Thank you.

[/quote]Depends on the vehicle. Some vehicles disconnect the load wire when the vehicle isn't running. Others have some kind of special protection circuit that would prevent battery draining. You'd need to check your manual or test it with a multimeter to know for sure.

[david]

I am pretty sure that all factory wired 7 pin systems have a relay (electronic probably) that disconnects the TV's battery from the trailer when the ignition is off.

You can check this yourself. Check the voltage at the trailer's battery with the TV's engine running. Then turn it off and wait an hour. If the voltage has dropped a half a volt or so then the relay is disconnecting it.

David

[tinkeringtechie]

[quote source="/post/3533/thread" timestamp="1410545486" author="@david"]I am pretty sure that all factory wired 7 pin systems have a relay (electronic probably) that disconnects the TV's battery from the trailer when the ignition is off.[/quote]Some vehicles don't even have the charge line enabled unless you install a relay/fuse (I think Fords used to come this way). And a lot of users in this forum had to install 7-way plugs since their vehicle only had a 4-way, so it really depends on how the installer put it in.
[quote source="/post/3533/thread" timestamp="1410545486" author="@david"]You can check this yourself. Check the voltage at the trailer's battery with the TV's engine running. Then turn it off and wait an hour. If the voltage has dropped a half a volt or so then the relay is disconnecting it.[/quote]This test won't tell you anything because even if they were connected the voltage would drop on both batteries. If you want to test it, just disconnect the trailer and check the voltage between pins 1 and 4 on the vehicle with a multimeter (it should be around 14 volts). Now turn off the vehicle and check those same pins again (it should show 0 volts, or float around 0). If it doesn't show 14 volts when you're running then it's always disconnected, and if it shows a voltage when it's not running then it's always connected. Here's a pin diagram:


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[david]

You are correct bout testing. My brain wasn't in gear!!!

David

[leslie]

The tow package on my 2014 Jeep Grand Cherokee has an automatic cut-off for the trailer when the engine is shut off. Any electricity for the trailer will come from the trailer's battery.

[tinkeringtechie]

[quote source="/post/3539/thread" timestamp="1410558855" author="@david"]You are correct bout testing. My brain wasn't in gear!!!

David[/quote]I call those brain farts. Last night I went to open a beer and proceeded to bring the can opener toward the edge of my empty glass 

[tinkeringtechie]

[quote source="/post/3544/thread" timestamp="1410561178" author="@leslie"]The tow package on my 2014 Jeep Grand Cherokee has an automatic cut-off for the trailer when the engine is shut off. Any electricity for the trailer will come from the trailer's battery.[/quote]This is exactly how it should work. When you get your trailer you should still check the voltage at the battery while the car is running to make sure it's charging (>13.5V)

[ron]

As always, great info and great information.  Thank you all for your time.  I copied the diagram to my ever growing file of RV info.  happy camping.