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isolation of 12v constant trailer-plug circuit

shavano

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shavano New Member

shavano

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2009 Silverado 1500 factory trailer package

 

I have connected the provided 12V constant power wire from the under-hood harness, onto the right-side post with 40A fuse. This will transfer a trickle charge to my camper battery via the 7-pin trailer plug.

 

This post is unswitched, i.e. always on. I would prefer that it be switched with the ignition ON, to avoid any possible use of the truck starter battery by the camper load when truck's engine is off.

 

However, I cannot find any confirmation that this circuit has any protection provided by the factory. The wiring diagram does not indicate any diodes or other protection, that I can see.

 

Does anyone happen to know if this circuit is protected from significantly drawing on the truck battery when engine is off?

 

A workaround is to install a relay by tapping into a switched circuit's fuse.

 

Thanks,

Bob

anumber1 Enthusiast

anumber1

Posted
Posted

Adding a relay is how I have addressed wiring power to my camper with my 99.

 

It has worked well for me.

shavano New Member

shavano

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yes, I just added the relay today. But if anyone does know if the factory trailer package has its own circuit protection, I'd like to know.

aeblank Enthusiast

aeblank

Posted
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I don't have a link, but a neat product is one that is basically a voltage controlled relay. If the source battery is over some value (13 volts?), then it charges the load batteries. Similar in function to a keyed relay, of course, but let's you have any source of charging while protecting your starting battery. We use one for trolling motor batteries on a fishing boat. In theory, one solar panel charger would eventually charge all batteries automatically.

 

Sent from my XT1254 using Tapatalk

shavano New Member

shavano

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good idea on the fancier relays. my auto mechanic says that some trucks's software is already programmed to recognize a second battery and will regulate charging volts accordingly (presumably for the accessory battery slot at the front corner of Silverados). Not sure if this would happen with the trailer outlet's battery.

 

I have solar and a controller already in the camper, but the manufacturer bypassed the controller by routing the trailer outlet directly to the house battery (and using too thin a wire). I'd have to not only rewire the camper but confirm that I can use the solar controller to regulate the truck-sourced voltage.

 

Meanwhile the inexpensive plain relay will at least keep the camper from drawing down the truck battery when parked.

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