How to connect TV hot wire to charge camper battery... - Fiberglass RV
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Old 07-14-2012, 07:48 PM   #1
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Name: Sherman
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How to connect TV hot wire to charge camper battery...

I'm going to apologize right off the bat here because it really feels like I should have been able to google this answer, but I just couldn't seem to hit on the correct search phrase.

I have just installed a new 7-prong connector on my TV. I ran a hot wire through a 40 amp breaker to the black wire on the new connector. Tomorrow I plan to upgrade the connector on my Trillium to 7-prong.

Right now I have a nice PD converter/charger charging my camper battery when it's connected to shore power. How do I wire the hot wire from the connector inside the camper so that it will charge the camper battery while I'm towing? Do I just connect it the positive terminal on the camper battery? That seems way too simple.

Thanks!
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Old 07-14-2012, 09:16 PM   #2
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Originally Posted by spotcatbug View Post
I'm going to apologize right off the bat here because it really feels like I should have been able to google this answer, but I just couldn't seem to hit on the correct search phrase.

I have just installed a new 7-prong connector on my TV. I ran a hot wire through a 40 amp breaker to the black wire on the new connector. Tomorrow I plan to upgrade the connector on my Trillium to 7-prong.

Right now I have a nice PD converter/charger charging my camper battery when it's connected to shore power. How do I wire the hot wire from the connector inside the camper so that it will charge the camper battery while I'm towing? Do I just connect it the positive terminal on the camper battery? That seems way too simple.

Thanks!
It is WAY too simple.
Connect the charge wire from the RV plug to the positive post of the battery. Also be sure that the negative post is connected back through the ground in the RV plug. (Many already are!)
I would suggest putting a lit 30A switch inside the Tow Vehicle in the charge wire as a convenient way to disconnect the charge wire when stopped with the trailer connected.
Or you could choose a battery Isolator, or a constant service relay.
Below there is ,a picture of an isolator , a picture of a constant service solenoid, and a picture of a "devils fork" just to make it seem complicated!
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Old 07-14-2012, 09:17 PM   #3
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You got it.
it's that simple.
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Old 07-15-2012, 05:56 AM   #4
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You need a circuit breaker on the trailer battery to TV wire, as well, in case that wire gets crimped. The trailer battery would fry the wire.
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Old 07-15-2012, 07:28 AM   #5
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Awesome.

Thanks guys!

Just so I understand what's what when I'm done doing this: if I connect the hot wire and the ground from the TV to the camper battery, without an isolator, solenoid or switch (or devil's fork ), I'm essentially turning the camper and TV batteries into one large battery, correct? Or actually, it seems more like the two electrical systems will become one. So the TV's alternator will charge the TV and the camper batteries. In addition, when I'm connected to shore power, and if I were to have my TV hooked-up, my camper's converter/charger would charge the camper battery and the TV battery.

Actually, now that I've typed all that, it seems like the batteries themselves would charge each other to some sort of equilibrium.

Is all that OK? Or is my simplistic knowledge of electrical stuff messing up my understanding?
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Old 07-15-2012, 01:39 PM   #6
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...........
Is all that OK? Or is my simplistic knowledge of electrical stuff messing up my understanding?
You need a solid state isolator or relay between the TV battery and trailer battery so that they are not connected when the vehicle is not running. A relay gives less voltage drop, which is important.

You need a fuse or circuit breaker at both batteries to prevent a fire if the connecting wire is shorted.

The connecting wire should 10 gauge or heavier to prevent above mentioned voltage drop.
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Old 07-15-2012, 02:17 PM   #7
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OK, thank you.

I'll be sure to get those parts (isolator or relay and another breaker).

I love this forum.
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Old 07-15-2012, 10:47 PM   #8
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You need a solid state isolator or relay between the TV battery and trailer battery so that they are not connected when the vehicle is not running. A relay gives less voltage drop, which is important.

You need a fuse or circuit breaker at both batteries to prevent a fire if the connecting wire is shorted.

The connecting wire should 10 gauge or heavier to prevent above mentioned voltage drop.
A relay is merely a switch, I use a manual switch with no relay or isolator.
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Old 07-15-2012, 11:02 PM   #9
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Awesome.

....Actually, now that I've typed all that, it seems like the batteries themselves would charge each other to some sort of equilibrium.

Is all that OK? Or is my simplistic knowledge of electrical stuff messing up my understanding?
Oh yes they would reach an equilibrium. As in your tv battery would go down as your trailer battery did. Not a good thing.

A lot of people wire a relay so the on/off power comes from an accessory circut. Car off = relay off, car on = relay on. Just don't leave the car in acc so you can listen to car radio for half the day because relay will draw power, some folks add a power switch for the relay in the car in addition to being on acc circut.


FYI - I was at HD today and 10 ga wire was 47 cents a foot. But someone here suggested checking a local scrap metal yard where one can get it for like half that.
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