Can I tap into trailer 7-pin 12v power?

[xcntrk]

I'm looking for a 12v power source to run my air-bags compressor. The 7-pin trailer harness connection at my hitch has a switched ignition 12v 30amp source that would be perfect. The compressor requires switched ignition and 15-amps.

But then I got to thinking, what is using this 12V power source when I have my TT hooked up and might that amp draw combined with the compressor amp draw, exceed the 30-amp fuse in the fuse box? Apparently it's supposed to "charge the battery" but what exactly does that mean? Is there a built-in trickle charger somewhere? Obviously my TT has a battery and converter with a built in 12v charger that when plugged into 120v shore power charges the 12v system. But is all that actually running off this 12v source when the trailer is hooked up going down the road? Anybody know if this is a good power source for an airbag compressor?

[timdan94]

xcntrk wrote:

wcjeep wrote:
Wouldn't it be faster to run home run wire from the battery to compressor location than messing with 7 pin factory wiring.

The compressor kit requires switched ignition power, otherwise it will constantly consume power when the rig is off keeping the bags at pressure. So no, a direct line to the batt won't do any good here. Also this kit has a wireless controller so the pump & manifold are installed on the exterior (either engine bay or under the rig) and no wiring or controls penetrate the interior cabin.

hammer21661 wrote:
Run a wire from the battery to a solenoid then hook the solenoid to a switched circuit. Always remember to fuse it. I don't know but the vehicle could have provisions for something like that.

This is how I would normally do it in using a relay with constant power source and trigger off switched ignition source. However the kit comes will all that as part of the harness and all you do is wire up a single supply to 15-amp switched source. I've dug through my engine bay fuse box looking for a switched power source and nearly every circuit is constant power. The only switched circuits are all power control modules for the engine which I'd prefer to stay away from.

I think I'll use the 30amp trailer switched power and throw an extra fuse in the glovebox. If I ever encounter a problem where the trailer draw and air-bag compressor draw over-subscribe this circuit at least I'll have an extra fuse to restore power if necessary.

if your compressor has to run to keep your bags up to pressure you have a leak somewhere. I've had bags on my last truck and my current one and never have issues with the bags leaking down.

[xcntrk]

wcjeep wrote:
Wouldn't it be faster to run home run wire from the battery to compressor location than messing with 7 pin factory wiring.

The compressor kit requires switched ignition power, otherwise it will constantly consume power when the rig is off keeping the bags at pressure. So no, a direct line to the batt won't do any good here. Also this kit has a wireless controller so the pump & manifold are installed on the exterior (either engine bay or under the rig) and no wiring or controls penetrate the interior cabin.

hammer21661 wrote:
Run a wire from the battery to a solenoid then hook the solenoid to a switched circuit. Always remember to fuse it. I don't know but the vehicle could have provisions for something like that.

This is how I would normally do it in using a relay with constant power source and trigger off switched ignition source. However the kit comes will all that as part of the harness and all you do is wire up a single supply to 15-amp switched source. I've dug through my engine bay fuse box looking for a switched power source and nearly every circuit is constant power. The only switched circuits are all power control modules for the engine which I'd prefer to stay away from.

I think I'll use the 30amp trailer switched power and throw an extra fuse in the glovebox. If I ever encounter a problem where the trailer draw and air-bag compressor draw over-subscribe this circuit at least I'll have an extra fuse to restore power if necessary.

[wcjeep]

Wouldn't it be faster to run home run wire from the battery to compressor location than messing with 7 pin factory wiring.

[hammer21661]

Run a wire from the battery to a solenoid then hook the solenoid to a switched circuit. Always remember to fuse it. I don't know but the vehicle could have provisions for something like that.

[beergardens]

I made a simple adapter to use on my truck. It's just 2 wires with a 7 pin connector (trailer end) on one end, and a female 12volt cigar lighter style receptacle on the other end. It allows me to plug a small 12v compressor into the rear or my truck for filling tires and such. It would also be useful for filling airbags etc. while the truck is stopped.

[720Deere]

As long as your trailer battery is not extremely weak and you have no large 12v power draws in the trailer when you are using the compressor, there should be no issue. The only time the trailer battery is going to draw a lot of amps is if it is in a low state of charge.

There is no 12v activated charger. The 12v connection to the truck simply charges the trailer battery just as it does your truck battery.

[Francesca_Knowl]

That charging line goes directly to your trailer battery, and yes, it will be charging while you're going down the road. Presumably the alternator stops sending juice down there at some point, once all batteries are charged.

Dunno if that circuit can "share" with your air bags, which I think is what you're asking....I'll be interested to see the answer from the experts.