7 Pin 12v To Trailer

[kipkohl]

Sorry if this has been asked and answered somewhere, but I couldn't find the answer.
So, when the truck is shut off is power to the trailer also shut off?

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[Dgc333]

Yes, it has to sense a trailer is connected before trailer power and brake power is available.

 

[kipkohl]

OK, good. Thank you. Let me rephrase my question. If the trailer is hooked up to the truck, and the truck is shut off, does the trailer still draw power from the truck battery?

 

[kipkohl]

OK, I get it now. Thanks for your reply, Dgc333

 

[JonB]

Sorry if this has been asked and answered somewhere, but I couldn't find the answer.
So, when the truck is shut off is power to the trailer also shut off?

I saw and responded to your post in another area about a DC-DC charger for your trailer. Seeing this post here I want to make sure you know that the wire in your 7-wire trailer pigtail that charges your batteries will only deliver 3-5 amps. It is not heavy enough to handle the higher current that LiFePO4 batteries will draw through the DC-DC charger. Folks who install these chargers (like me) disconnect the charging wire in the pigtail and run new, heavier wires, to the batteries.

 

[kipkohl]

So I am still a little unclear about this (sorry, I can be a little slow at times). If I have a trailer with 380 watts of solar, a lithium compatible charge controller, and 200ah of LiFePO4 batteries with battery management, can I skip the dc-dc charger without putting my stock alternator at risk?

 

[JonB]

To answer your latest question, if the panels are always on they will charge the batteries while your trailering. However, if there is little sun, it’s raining, it’s cloudy, etc., they will provide little if any charge. So, it’s up to you. Just go with the solar and hope there’s enough sun to keep the batteries charged or work out a way to charge them when towing from the vehicle.

 

[kipkohl]

Thanks for your reply but, my concern is not charging the batteries, my concern is if the truck's alternator can be be damaged by the lithium draw through the 7 pin connector.

 

[ctechbob]

There should be an appropriately sized fuse on that line from the factory, it will pop before there's any damage done to the alternator.

I believe the BCM controls the line as well, so if it ends up pulling too much current it can probably detect that and shut it down.

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