Solenoid for 12V trailer connection - what to connect

[Jameson]

Hi all,

I have a 12v Anderson connector that leads from the battery in my 4Runner to my trailer. Right now, it's hot 100% of the time. I would like to install a solenoid to prevent the current from flowing when my vehicle is off.

Does anyone have a tip on what I should connect the solenoid to to accomplish this. I could install a switch in the cab, but would prefer if this was tied to something that was only hot when vehicle is running.

Jameson

 

[benjrblant]

Blue Sea ACR? Sounds like this will accomplish what you're looking for.

 

[Jameson]

Blue Sea ACR? Sounds like this will accomplish what you're looking for.

It would, but I would prefer to accomplish this with a $20 120 amp solenoid vs. a $120 ACR. This will run into a Redarc system in my trailer - so I'm not worried about the startup protection the ACR provides.

 

[DaveInDenver]

If you're talking about a Redarc charger (like a BCDC series) then it's designed to disconnect itself when the voltage drops, e.g. it sense when the vehicle charging system is running or not. The standard settings are to turn on when the vehicle side hits 13.2V and off at 12.7V.

What are you trying to accomplish with an additional solenoid when you already have a smart charger?

But if you are dead set on doing it, find an ignition hot wire to trigger the solenoid. Doesn't matter where you pick it up, there's tons of ways to do it. Your 4Runner has a 12V cigarette lighter in the cargo bay that by default is only on with the key, for example.

 

[Jameson]

If you're talking about a Redarc charger (like a BCDC series) then it's designed to disconnect itself when the voltage drops, e.g. it sense when the vehicle charging system is running or not. The standard settings are to turn on when the vehicle side hits 13.2V and off at 12.7V.

What are you trying to accomplish with an additional solenoid when you already have a smart charger?

But if you are dead set on doing it, find an ignition hot wire to trigger the solenoid. Doesn't matter where you pick it up, there's tons of ways to do it. Your 4Runner has a 12V cigarette lighter in the cargo bay that by default is only on with the key, for example.

The Redarc was in the trailer. I guess it's not critical that I have a solenoid (or could just use a manual switch), but I just felt that there wasn't a need to have the cables running to the back of the 4Runner hot all of the time. Noted on the 12V cigarette lighter...

 

[nakman]

Have you tested the lead at the harness with a multimeter when the truck is off? You may discover that it's actually off, like Dave suggests.

If it's hot, then I'd probably use a light relay- easy to wire up, just put the switch terminal to something that switches on with ignition. To that end, I've got an extra one you can have.

 

[DaveInDenver]

I dunno, I wouldn't worry about it even if it is always hot. The Redarc does it's thing as designed when the trailer is plugged in. With no trailer even hot no current can flow.

 

[Inukshuk]

Solenoid or not, priotect the line by fusing that cable at the battery: Single Terminal (1/4" Stud) MRBF Fuse Block 30 to 300A - Marine Rated Battery Fuse (MRBF) https://www.amazon.com/dp/B07L6RDMDP/ref=cm_sw_em_r_mt_dp_U_UDKRCb8HJ0R5T

 

[DaveInDenver]

Solenoid or not, priotect the line by fusing that cable at the battery: Single Terminal (1/4" Stud) MRBF Fuse Block 30 to 300A - Marine Rated Battery Fuse (MRBF) https://www.amazon.com/dp/B07L6RDMDP/ref=cm_sw_em_r_mt_dp_U_UDKRCb8HJ0R5T

And bring spares, right @Mendocino? ;-)

 

[Jameson]

Solenoid or not, priotect the line by fusing that cable at the battery: Single Terminal (1/4" Stud) MRBF Fuse Block 30 to 300A - Marine Rated Battery Fuse (MRBF) https://www.amazon.com/dp/B07L6RDMDP/ref=cm_sw_em_r_mt_dp_U_UDKRCb8HJ0R5T

I do have a 60amp marine rated battery fuse. Now all I need is spares! Thanks all!