Tow Vehicle Battery Drained

[gjarrette]

I have owned my Forest River Freedom Express Travel Trailer for 3 years.

I have 4 100 watt solar panels and a 200 amp hour battery which is fully charged all the time via the panels.

Recently for the first time I left the trailer plug, plugged into the Ford F-150 for 5 days without running the F-150 at all.

I went to start it the other day and the truck battery was dead. The battery is only 4 months old so in effect new. I know the truck is supposed to charge the trailer battery but why did the trailer drain the truck battery? Very strange.

So I did unplug the trailer from the truck and charge the truck battery. Everything is fine now. What gives with this scenario? Why would the trailer drain the Truck battery? No running lights were left on either.

Also I did not have the emergency brake switch safety disconnect pulled out I know this will apply the trailer brakes on. Learned that the hard way.

[oxcamper]

Yep --
Lesson Learned.
You're not the only one!

[Oaklevel]

Originally Posted by gjarrette

I have owned my Forest River Freedom Express Travel Trailer for 3 years.

I have 4 100 watt solar panels and a 200 amp hour battery which is fully charged all the time via the panels.

Recently for the first time I left the trailer plug, plugged into the Ford F-150 for 5 days without running the F-150 at all.

I went to start it the other day and the truck battery was dead. The battery is only 4 months old so in effect new. I know the truck is supposed to charge the trailer battery but why did the trailer drain the truck battery? Very strange.

So I did unplug the trailer from the truck and charge the truck battery. Everything is fine now. What gives with this scenario? Why would the trailer drain the Truck battery? No running lights were left on either.

Also I did not have the emergency brake switch safety disconnect pulled out I know this will apply the trailer brakes on. Learned that the hard way.

Not strange at all there are still parasitic draws from CO detector, and other misc things in the trailer and from the truck as well. You learned a valuable lesson.

[PhilFromMaine]

Originally Posted by gjarrette

I have owned my Forest River Freedom Express Travel Trailer for 3 years.

I have 4 100 watt solar panels and a 200 amp hour battery which is fully charged all the time via the panels.

Recently for the first time I left the trailer plug, plugged into the Ford F-150 for 5 days without running the F-150 at all.

I went to start it the other day and the truck battery was dead. The battery is only 4 months old so in effect new. I know the truck is supposed to charge the trailer battery but why did the trailer drain the truck battery? Very strange.

So I did unplug the trailer from the truck and charge the truck battery. Everything is fine now. What gives with this scenario? Why would the trailer drain the Truck battery? No running lights were left on either.

Also I did not have the emergency brake switch safety disconnect pulled out I know this will apply the trailer brakes on. Learned that the hard way.

My guess is that something in the vehicle was in fact on. In my experience stupid stuff that you would never suspect. Doors not fully shut or dome lights left on or malfunctioning. Was the TT battery still fully charged?

[gjarrette]

Yes but the question still is why would it do that.

If this is normal then yes I will not make that same mistake twice but I would rather find a permanent solution like cut a wire or install a diode or such so if I did leave the trailer plug in it COULD NOT DISCHARGE THE TRUCK BATTERY below say 10.5 volts.

I would imagine it is a safety precaution to keep the trailer battery charged just in case you needed for the emergency pull out plug out to apply the brakes but in my case the trailer battery is always kept charged by a more than ample solar array. This makes sense. Trailer breaks loose, plug pulls out and safety brake pin pulls out. Trailer battery is not the brake battery.This is lousy engineering. Your primary battery should never be allowed to discharge to dead which is bad for the battery.

Even I think that a low battery condition should sever the connection automatically through a voltage sensing device. Discharge to dead will killl the battery life.

[Bogieboy]

you could install one of these on your TV between the engine battery and the trailer wiring harness, allows voltage thru to charge your trailer battery, but if the load draws the trailer battery down, it disconnects from the system and leaves you with enough starter battery voltage to start the vehicle.

https://www.batterymart.com/p-acc-20...-isolator.html

[NMWildcat]

Most modern pickups that come with a 7pin connector from the factory have an ignition switched isolator to prevent your trailer from draining your TV battery when the engine is not running. But not all of them, so you need to test to see if yours does or not.
That being said, it is always a good habit to unplug the 7pin when leaving your RV hitched overnight. I'm old and have always done this since I was a kid. Better safe than sorry.

[justskipit]

Not sure what year your t/v is, but when you shut off your engine it should cut off your t/t from your t/v. I know mine does.

[Reverse_snowbird]

Originally Posted by gjarrette

Recently for the first time I left the trailer plug, plugged into the Ford F-150 for 5 days without running the F-150 at all.

Five days gives a parasitic draw from the trailer a long time to drain the truck battery. Or it could be that the truck 'monitors' that connection, although that would be unusual.

[justskipit]

In any case when you shut your key off it should disconnect your t/t from your t/v. As far as your brake disconnect your t/t batt. will work that not your t/v.

[Mr. Dan]

Originally Posted by justskipit

In any case when you shut your key off it should disconnect your t/t from your t/v. As far as your brake disconnect your t/t batt. will work that not your t/v.

Mine doesn’t disconnect. My 7-pin is always hot regardless of ignition switch position.

[jkoenig24]

Does your trailer have a THREE WAY refrigerator (110VAC / 12VDC / Propane)? If so, the fridge will AUTOMATICALLY SWITCH to whatever power is available unless you set it to NOT do that. The first night I had my SOB trailer, I neglected to unplug the 7-Way plug. Next morning, my tow vehicle had a dead battery. The battery was a relatively new Sears Die Hard. I got a jump for the battery and drove away. A few hours later, I saw a Sears store just off the highway. I pulled into the Sears Auto Center and, had Sears check the battery and charging system. Everything checked out OK and, I dodged a bullet on my mistake.

[gjarrette]

My Fridge is only two way 110 from shore power or Propane so no draw there.

I believe my plug remains hot with ignition off.

I have checked the price of the Battery Doctor, kind of expensive at $80.00 on Amazon but you have pointed me in the right direction and I found that there are several of these gadgets and they range from $40.00 $90.00 each providing some different options, LEDs, digital readouts, etc.

The stinger looks good and some have digital readouts. I am looking into these units to make my setup more fool proof but you know what they say; "fools are the most ingenious people you will ever meet".

Preferably one would think that the F-150 or any other Tow Vehicle would have one of these so a person does not get stranded but then again that is what I get for thinking. One would think that when if you buy a truck with the towing package that it would have this feature built in and when the battery reaches a certain low level that any discharge beyond that point would disconnect the trailer battery so as to provide you with enough reserve power to crank the engine. But I understand the mentality of the auto manufactures. If they can save a dime on a million vehicles they will do it and to hell with you. It is a sad testament to the human race but we are what we are, flawed, and the almighty dollar is our God.

I am grateful for all the information all of you so generously and graciously provided me. I thank you all for taking the time to lend a hand.

I think I have a handle on it now.

Take care all of you my friends and God bless.

Gary Jarrette AKA Maximus

[Bogieboy]

Originally Posted by gjarrette

My Fridge is only two way 110 from shore power or Propane so no draw there.

I believe my plug remains hot with ignition off.

I have checked the price of the Battery Doctor, kind of expensive at $80.00 on Amazon but you have pointed me in the right direction and I found that there are several of these gadgets and they range from $40.00 $90.00 each providing some different options, LEDs, digital readouts, etc.

The stinger looks good and some have digital readouts. I am looking into these units to make my setup more fool proof but you know what they say; "fools are the most ingenious people you will ever meet".

Preferably one would think that the F-150 or any other Tow Vehicle would have one of these so a person does not get stranded but then again that is what I get for thinking. One would think that when if you buy a truck with the towing package that it would have this feature built in and when the battery reaches a certain low level that any discharge beyond that point would disconnect the trailer battery so as to provide you with enough reserve power to crank the engine. But I understand the mentality of the auto manufactures. If they can save a dime on a million vehicles they will do it and to hell with you. It is a sad testament to the human race but we are what we are, flawed, and the almighty dollar is our God.

I am grateful for all the information all of you so generously and graciously provided me. I thank you all for taking the time to lend a hand.

I think I have a handle on it now.

Take care all of you my friends and God bless.

Gary Jarrette AKA Maximus

apples to apples, i thought the battery doctor was cheap...LOL the other 150 capable ones i saw were more in the 150+ range... (i would run at least whatever amperage your TV puts out for charging, but i am known for total overkill...LOL)

[david_reaves]

For others that search and see this post, it may be fairly common to have the 7-pin plug hot with the ignition off. My 2014 RAM 3500 connector is also always live. The trailer and the taillights/flashers can drain the battery more quickly than you think, too. I had flashers on with the trailer and a flat tire beside I-40 a couple of years ago... didn't run the truck since gas was low. By the time road service arrived and the tire was changed (about four hours) the battery was too low to start the truck!

[Stormy Dayton]

I'm with Phil from Maine, It seems more likely to me that something in the truck killed your battery.

[CaptnJohn]

15 F250, 17 and 19 F350 have been left connected for up to over 3 weeks and always start

[rekaj321]

Originally Posted by gjarrette

I have owned my Forest River Freedom Express Travel Trailer for 3 years.

I have 4 100 watt solar panels and a 200 amp hour battery which is fully charged all the time via the panels.

Recently for the first time I left the trailer plug, plugged into the Ford F-150 for 5 days without running the F-150 at all.

I went to start it the other day and the truck battery was dead. The battery is only 4 months old so in effect new. I know the truck is supposed to charge the trailer battery but why did the trailer drain the truck battery? Very strange.

So I did unplug the trailer from the truck and charge the truck battery. Everything is fine now. What gives with this scenario? Why would the trailer drain the Truck battery? No running lights were left on either.

Also I did not have the emergency brake switch safety disconnect pulled out I know this will apply the trailer brakes on. Learned that the hard way.

Kept telling forest river there was an issue with charge drain. They said no but....new wolf pup 2021 has a complete shutoff switch when parking rig to eliminate this "non existant" drain ha lesson learned

[DouglasReid]

Originally Posted by NMWildcat

Most modern pickups that come with a 7pin connector from the factory have an ignition switched isolator to prevent your trailer from draining your TV battery when the engine is not running. But not all of them, so you need to test to see if yours does or not.
That being said, it is always a good habit to unplug the 7pin when leaving your RV hitched overnight. I'm old and have always done this since I was a kid. Better safe than sorry.

Ya know I always thought my 12V pin was hot, then I checked it and found it was not. I did activate it, on my 08 Silverado, by finding the lead under the hood and connecting it to Post #2 on the under hood fuse box. Now it is constantly hot whetherthetruckis running or not.

Ive always unplugged the camper overnight as well, but Im going to install a solenoid using an ignition switched fuse location to make sure, just in case I break that life long habit.

[Comanchecreek]

You need a battery isolator relay. Juice is only shared between the sets of batteries when the key is on. Most trucks are hot always at the wire that connects the truck batteries to the RV batteries. It's a fairly simple addition. Google it.