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Trickle charging. Has anyone else tried this...?

0051 MAR

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I have a take home work vehicle, so I don't get to drive my truck as often as I'd like to. I leave the dash came running since the truck stays outside. I was noticing that the camera shut off (power saving mode) after only 2 days or so. I used to trickle charge my Charger and that worked out since the battery was in the trunk and I always back in the driveway (better camera view).

I was looking for a way to trickle charge my Ram, but I didn't want to run a cord all the way under the hood. Then I had a thought...the 7-way trailer port. I checked and sure enough, the 12v pin stays active even when the truck is off. So I wired a trickle charger into a 7-way trailer connector. It works really well.

I'm not sure if anyone else has tried this before but maybe someone else will find this helpful!
 

jimk hunt

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Do you have a pic of how you wired this? I like this idea vs permanent leads running off the battery.
 

djevox

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I'll start this by saying this is my educated opinion and everyone is free to do what they want. This advice is worth the price charged.
After tracing wiring diagrams for this, I feel this is a recipe for disaster. From frying modules just by me checking a wire on ECU's and BCM's with a test light, the battery charger is much, much worse. You are essentially "backfeeding" (for lack of a better term) the 12v circuits. The battery has intelligent monitoring and there are safeties in place that expect a flow of current in certain directions. Diodes are directional for a reason- when there is reverse bias, the diode breaks down to allow current to continue flowing. It amazes me nothing has fried yet; I'm hoping that's because engineers have thought of similar scenarios and prevented that possibility.
 

Cbty2050

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I'll start this by saying this is my educated opinion and everyone is free to do what they want. This advice is worth the price charged.
After tracing wiring diagrams for this, I feel this is a recipe for disaster. From frying modules just by me checking a wire on ECU's and BCM's with a test light, the battery charger is much, much worse. You are essentially "backfeeding" (for lack of a better term) the 12v circuits. The battery has intelligent monitoring and there are safeties in place that expect a flow of current in certain directions. Diodes are directional for a reason- when there is reverse bias, the diode breaks down to allow current to continue flowing. It amazes me nothing has fried yet; I'm hoping that's because engineers have thought of similar scenarios and prevented that possibility.
What diodes did you see in the wiring diagram?
 

ekaz

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I would have to agree, I'd be concerned back feeding power through the trailer connection, but I do like the idea. I have a NOCO trickle charger that I left connected to a battery and they sell extension cables, so maybe run that to the back?
 

RHeller1

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"Yeah! I'll bet he also leaves his ring security cameras on even when he's not home."
"Yea let me just leave my camera on in my car while its parked in my driveway so it can record the garage wall. lol"

Was it?
 

Awood05

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@0051 MAR I truly appreciate your ingenuity. As someone who spent 18 years designing electrical circuits for work truck equipment I truly am impressed. @djevox has a valid point, but without studying the schematics of our trucks I can’t comment on that one way or another. It really depends on the path the trailer battery wire takes back to the battery. As long as it works and you don’t start seeing any electrical glitches with other systems you could be fine. Kudos.

For those interested, here is a diagram of the standard 7-way trailer socket on our trucks. The ‘black’ terminal is likely what he hooked the positive up to. And the ‘white’ was attached to the ground.

7-way rv wiring.jpg
 

djevox

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I have a little bit different wiring colors for '21 and '22. I can't post the full diagram, but here's a snippet that shows the color breakdown. I traced it and red is the 12v+ constant, white is ground, black is 12v+ switched for backup relay, dark blue is electric brake feed, dark green is 12v+ switched right trailer tow relay, brown is 12v+ switched trailer tow park lamp relay, and yellow is 12v+ switched left trailer tow relay.

Screenshot from 2022-02-05 08-40-44.png
 

kapinallinen2

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The pin E in the 7 way will back feed through 30 amp. fuse 01 in the PDC,interior.
From there it goes through the parallel f 204 and f 205 80 amp. fusible links to PDC in engine compartment and from there straight to the battery.
No relays or diodes involved, I do not see a problem with OP`s way of connecting to the charger, YMMW.
 

0051 MAR

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I'll start this by saying this is my educated opinion and everyone is free to do what they want. This advice is worth the price charged.
After tracing wiring diagrams for this, I feel this is a recipe for disaster. From frying modules just by me checking a wire on ECU's and BCM's with a test light, the battery charger is much, much worse. You are essentially "backfeeding" (for lack of a better term) the 12v circuits. The battery has intelligent monitoring and there are safeties in place that expect a flow of current in certain directions. Diodes are directional for a reason- when there is reverse bias, the diode breaks down to allow current to continue flowing. It amazes me nothing has fried yet; I'm hoping that's because engineers have thought of similar scenarios and prevented that possibility.
I think you are overlooking one thing and therefore way overthinking this...that pin on the trailer plug is designed to charge a trailer's 12v system which has its own 12v battery which will also "backfeed" the circuit. That pin is essentially a battery terminal in the rear of the vehicle and not as protected or complex as you may think.
 

djevox

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I think you are overlooking one thing and therefore way overthinking this...that pin on the trailer plug is designed to charge a trailer's 12v system which has its own 12v battery which will also "backfeed" the circuit. That pin is essentially a battery terminal in the rear of the vehicle and not as protected or complex as you may think.
I saw a lot of modules in that path. All I am saying is from experiencing how easy it is to fry something, that I think it’s a bad idea. Like I said, my opinion is my own and people can do whatever they want.
 

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