One way juice.

[sogncab]

I've been monkey humping this idea for a while. I'm going to try and actually make it work now.

My little camp trailer. I 3D printed a box to hold some switches, and a USB port.
Turned out sweet I think. This is just out of PLA, and it's probably version 6.... I'll print the final from PETG

Switches are to kick on the light under the lid, and I want to be able to kick on the running lights, reverse lights, and rock lights underneath on the trailer. Which are just more of the 3/4" marker lights.

I want to be able to power those switches from either the tow vehicle power through the RV plug or from a battery in the trailer.

My concern is back feeding the tow vehicle lights. If I put juice to the running lights or the reverse lights, that will illuminate the lights on the tow vehicle.
I don't want that. All the lights are LED, and don't draw squat. To start with, I'm going to run everything off of a Makita tool battery until I decided what I want to do for power. There isn't a ton of Ah available, and I'm certain power up the incandescent bulbs on the vehicle will drain a small battery way fast. Where as just the trailer, it'll run a very long time on a single tool battery.



I don't know enough to determine what diodes I need to prevent the back feed. This is what I need and would appreciate help on.



Thinking now, I should probably put one on the battery power feed, and the vehicle power feed as well.
I could just unplug the trailer from the tow vehicle, but what's the fun in that.

 

[FrazzledHunter]

I've been monkey humping this idea for a while. I'm going to try and actually make it work now.

My little camp trailer. I 3D printed a box to hold some switches, and a USB port.
Turned out sweet I think. This is just out of PLA, and it's probably version 6.... I'll print the final from PETG


View attachment 4234791

View attachment 4234792


Switches are to kick on the light under the lid, and I want to be able to kick on the running lights, reverse lights, and rock lights underneath on the trailer. Which are just more of the 3/4" marker lights.

I want to be able to power those switches from either the tow vehicle power through the RV plug or from a battery in the trailer.

My concern is back feeding the tow vehicle lights. If I put juice to the running lights or the reverse lights, that will illuminate the lights on the tow vehicle.
I don't want that. All the lights are LED, and don't draw squat. To start with, I'm going to run everything off of a Makita tool battery until I decided what I want to do for power. There isn't a ton of Ah available, and I'm certain power up the incandescent bulbs on the vehicle will drain a small battery way fast. Where as just the trailer, it'll run a very long time on a single tool battery.



I don't know enough to determine what diodes I need to prevent the back feed. This is what I need and would appreciate help on.



Thinking now, I should probably put one on the battery power feed, and the vehicle power feed as well.
I could just unplug the trailer from the tow vehicle, but what's the fun in that.

I am assuming that the power from the tow vehicle to the trailer is on only when the ignition is on. If it isn't, and on all the time, consider adding a relay to allow power to the trailer only when the ignition is on. As for the trailer, maybe a relay or pair of relays that is energized when power is coming n in the tow vehicle? So, when power comes from the tow vehicle, one relay goes off and another comes on? Maybe a SPDT relay would do it. Hopefully this happens fast enough. I'm sure an EE could come up with something better.

Of course, You could make a manual switch setup. But then you have to remember to perform the switcdh LOL!

 

[sogncab]

I am assuming that the power from the tow vehicle to the trailer is on only when the ignition is on

Currently. There is no power. I still need to wire that in. Along with an RV plug on the 40.
My preference, would be it is always hot.
But a relay and a switch to kill it in the vehicle might be a good idea. I think I've got one for sure, possibly two open holes in the relay block I installed when I did the one that runs all of the aux lighting

 

[ntsqd]

Without being an EE. I'd expect that a 1N4005 diode for each circuit would be a good start.
OR could buy a MINI fuse holder block with enough circuits and populate it with these: https://www.waytekwire.com/product/littelfuse-02400104p-1a-mini-diode

 

[sogncab]

Without being an EE. I'd expect that a 1N4005 diode for each circuit would be a good start.
OR could buy a MINI fuse holder block with enough circuits and populate it with these: https://www.waytekwire.com/product/littelfuse-02400104p-1a-mini-diode

That's a really good idea with the fuse holder. I think the j box I bought might be large enough to package everything inside too.

Another idea might be to 3D print a holder for the solder in diodes. I can probably make that significantly smaller

 

[sogncab]

Might be easier yet to do a inline fuse holder.
I'm more likely to be able to pack them in the junction box then.