My 05 expedition has the heavy duty towing package, which includes a battery charging circuit for the trailer. Has anyone used this to charge the batteries on a boat while in route to the ramp?

 

That circuit is normally used to charge the small breakaway battery on trailers with electric brakes; I'm not sure it's wired/fused to handle high amp draws, especially on mutiple battery set-ups.

Steve

 

YES, the trailer charging circuit is designed to supply 12v 30a to the trailer batteries of a rv trailer in key-on position only. I have it on my 01' expy. You may have to go under the hood to the relay junction box and add the relay for it to work. Look at the schematic for the junction box to see if you already have the relay installed from the factory. Mine did not and it took $5.oo to get it working...

 

Did yours come with the 7-pin trailer connector/HD Factory Tow Package, or just the 4-pin flat connector?

TIA,

LM

 

I have TT and the TT battery is charged when towing. That's one of the reasons I splurged and got an Optima Redtop for the Expy. I keep waiting for the battery in the TT to die so I can purchase an Optima YellowTop for it. I've never done this, but I have heard of people when dry camping cranking their TV and letting it run to keep the TT batteries charged. At 2 dollars a gallon, I'll just sit in the dark.........

phil

 

Mine came with the 7 pin wiring that was connected to a 4-pin flat(factory). Ford wanted $80.00 for the 7 pin adapter, so i puchased a 7 pin "Hoppy" from the local parts store for $25.00 and spliced in to the factory harness. After that all i had to do was add the relay to space #302 in the relay junction box.

 

As 99expyTN said, at $2 gallon, sit in the dark. The alternator only puts out enough to maintain a charged trailer battery, you will go broke trying to idle it charged. I have dual alts on my 350, and it will gain you about 1 hr battery time with about 2 hrs idling time at 1200 rpm. If you need a short time of battery use, just plug the truck in and work off the truck battery, just don't drain it also. To correctly charge a trailer battery, you need a battery charger that starts out with high amps, then ramps down as the charge comes up.

If you head to the lake with low batteries, you probably can't drive far enough to charge them to any extent, especially if you use the a/c and stereo when driving.

 

Do you know what the part number for the relay that you added to charge the battery was? I'm getting conflicting answers from the Ford dealer.

Thanks in advance!

 

The relay that came with my 05 is part number F0AB-14B192-AA

 

Eric has the correct relay part number.