Unplug tow vehicle before plugging in shore power?

[caissiel]

Completely safe to stay connected. I always check the battery status after connecting to shore power and after connecting to the truck to check status of charge. It looks like a chore but its just routine for me. I always need to be aware. Like looking at my gauges when driving, prevents problems on the road. My truck gets plugged in often on the trailer here while parked for the last 3 months. No way my diesel charges the 2 batteries properly on short local milk trips.

 

[JohnD]

Completely safe to stay connected. I always check the battery status after connecting to shore power and after connecting to the truck to check status of charge. It looks like a chore but its just routine for me. I always need to be aware. Like looking at my gauges when driving, prevents problems on the road. My truck gets plugged in often on the trailer here while parked for the last 3 months. No way my diesel charges the 2 batteries properly on short local milk trips.

I don't believe that leaving the trailer connected to the truck while plugged in to shore power will keep the truck batteries charged!

The only charging going on through that connection is the truck charging the trailer batteries while the truck is running.

 

[caissiel]

I installed a decent line from the truck batteries to the trailer connection without a relay. The Ford battery wire was a joke trying to charge the trailer batteries with it. Also when overnighting I leave the truck connected to lower all the batteries. The alternator will operate at higher volts and charge the trailer batteries faster the next day.
I learned that after draining my trailer batteries to many times while traveling.

 

[Jim.Allison]

The house batteries are actually a convenient alternative for a dedicated power source for your breakaway brake system. Your 7 pin was never designed to charge a house battery, it is only designed to maintain a charge on a breakaway batt. The charge received through the 7 pin is slightly more than a batt maintainer.

If you want to charge house batteries while traveling, install a solar panel for about $500 and a couple of quality deep cycle AGM house batteries.

You might even install a separate dedicated starting battery for your generator and connect your breakaway switch to that source. Your TV will definitely keep that battery system charged, and if you need to maintain that battery while disconnected from the TV, then install a 120v outlet in the garage and use a dedicated battery maintainer to maintain the dedicated breakaway/generator starting batt. Which will charge from either pedestal power, or generator generator.

 

[avvidclif]

The house batteries are actually a convenient alternative for a dedicated power source for your breakaway brake system. Your 7 pin was never designed to charge a house battery, it is only designed to maintain a charge on a breakaway batt. The charge received through the 7 pin is slightly more than a batt maintainer.

I don't know about your truck but my Ford is more than a trickle charger. When I picked up a SOB at the dealer after repair and he didn't disconnect the battery I found the battery was completely dead. I hooked up the 7 pin plug and used the truck battery to raise the landing gear so I could hook up. The wire to aux power in the 7 pin is 10ga. Tell you anything?

 

[whp4262]

The battery in the used 2011 Trail Runner was dry when I purchased it. When inquiring, a friend told me the converter can boil the acid/water mix from battery if battery is left connected without use for a long time. The travel trailer I purchased was not used last year by previous owner. Have any here heard of this happening?

I haven't had a problem with the 5th wheel but I had to watch the batteries in my motor home. The motor home had an inverter that also charged the batteries instead of a converter and it would boil the water out of the batteries over time.

 

[Jim.Allison]

The pump motor is obviously less than a 10 amp motor, because that is about all you are going to get in a 15 to 25 foot section of 10AWG wire. It is good for max 15 amps at 12v and you will lose .6 v in a 20 foot circuit. If you have a an alternator charging at 13.4 V the best you are going to get to your house batt is 12.8v and maybe 15 amps. More likely less than that.

For a 50% discharged house battery, it would take every bit of 10 hours to charge it to anything remotely resembling a full charge.

BTW, I did not say that it was a trickle charge or battery maintainer, I said it was designed to maintain a charge on a breakaway battery. And that is was never designed to charge house batteries.

Further, if you are towing with a dead house batt, while it is being charged by your 7 pin, you do not have a battery capable of activating your electric breaks in the event of a breakaway until it reaches the voltage and amp capacity to activate it and hold the brakes.

I don't know about your truck but my Ford is more than a trickle charger. When I picked up a SOB at the dealer after repair and he didn't disconnect the battery I found the battery was completely dead. I hooked up the 7 pin plug and used the truck battery to raise the landing gear so I could hook up. The wire to aux power in the 7 pin is 10ga. Tell you anything?

 

[avvidclif]

Disagree, 10ga wire is rated for 30A. The alternator in a vehicle charges at ~14.5v until fully charged then drops, look it up.

In my Ford owners manual the "Trailer Battery Charging Circuit" has a 30A fuse.

 

[murry135]

All the above information is good but I have experienced only the opposite effect. After a long tow I realized my trailer batteries were dead and not recharging (however all trailer marker lights and brakes were operating due to 7pin plug). Follow up at a dealership in Goshen I was told to check the fuse that is part of my trailering package in my TV, Ford F350 DRW and when I did I found the fuse was blown resulting in no current to trailer batteries. I replaced fuse at local Ford dealership in Goshen where the service department explicitly told me NOT to leave unit plugged into shore power and the umbilical cord to TV connected at the same time. The results of such COULD be the fuse blowing upon a power surge. Since my experience I now make sure I do not plug coach in while connected to TV.

 

[Jim.Allison]

If you are getting 30 amps and 14.4 volts to your 10 awg breakaway charging wire, then you are not the person I was addressing my remarks.

I would never use a 30 amp fuse on a 10 AWG wire in an automotive application.

Disagree, 10ga wire is rated for 30A. The alternator in a vehicle charges at ~14.5v until fully charged then drops, look it up.

In my Ford owners manual the "Trailer Battery Charging Circuit" has a 30A fuse.

 

[Jim.Allison]

That makes sense, the breakaway battery charging circuit is separate than the signal circuits. And it makes sense that anything that is part of a system regardless of the components are subject to damages from incidences from any one part. So it all makes sense that an electrical abnormality could blow a fuse. But it is more likely that the fuse was blown by a temporary short, or overload and not a surge from the charger/converter. The Charger converter is also protected by blade fuses.

You need to protect your entire rig from power surges from shore power, or that little 30 cent fuse will be the least of your problems.

All the above information is good but I have experienced only the opposite effect. After a long tow I realized my trailer batteries were dead and not recharging (however all trailer marker lights and brakes were operating due to 7pin plug). Follow up at a dealership in Goshen I was told to check the fuse that is part of my trailering package in my TV, Ford F350 DRW and when I did I found the fuse was blown resulting in no current to trailer batteries. I replaced fuse at local Ford dealership in Goshen where the service department explicitly told me NOT to leave unit plugged into shore power and the umbilical cord to TV connected at the same time. The results of such COULD be the fuse blowing upon a power surge. Since my experience I now make sure I do not plug coach in while connected to TV.

 

[caissiel]

I was able to charge my batteries at a 23.4 amp rate from the truck idling. But the batteries were at less then 12 volts, also the generator was charging the batteries at the same rate using the trailer converter.
Therefore I decided that a 200 watt solar system was right for my application. While I never saw any decent battery charge using the generator for 2 hrs per day. The solar system charges the same batteries with same usage by 11 am every day.
My assumption is that at sundown the batteries are 100% while with converter they are at a little over 60%. The truck charging idling for more then 2 hrs was better then the generator/ converter combination any time.
The solar system does a great job at maintaining the batteries at 100%. Much better then the converter and no water loss to my 3 RV batteries an truck batteries.

 

[Jim.Allison]

The truck charging idling for more then 2 hrs was better then the generator/ converter combination any time.

What kind of charger/converter do you have?

 

[brianlajoie]

I have heard that if you have electric landing gear, you should avoid using the truck electrical system. Use shore power instead. The electrical landing gear could cause the TV fuse to fail. It is hard to detect a blown fuse until you start wondering why the trailer batteries are dead. After I heard that, I went and bought some extra fuses for the truck and trailer (I needed to anyway).

 

[murry135]

Regardless of all the information supplied above, and in saying that, I will continue to d/c TV before plugging in shore power and I will continue to recommend that to others. I know what I experienced and I am sure of what caused it and will not be told that something else was the cause. Sometimes it is the simplest cause that we refuse to accept that will cause us the most inconveniences.

 

[JohnD]

I posed another related question asking about turning engine of TV off when plugging or unplugging the trailer pigtail to the TV.

Here is the link:

https://heartlandowners.org/showthr...-trailer-pigtail-to-truck?p=413337#post413337

 

[Bohemian]

It would never occur to me to NOT disconnect the tow vehicle before connecting the trailer to power. Just one of those long experience inbuilt safety processes. Don't do dumb s***. Don't do stuff that might be dumb s***. There's more that I don't know then there is that I do know. I don't want to learn everything the hard way.

 

[Jim.Allison]

That is one way to put it. I hate it when I say to myself, "I knew when I did it that I should not have........" "Woops"

It would never occur to me to NOT disconnect the tow vehicle before connecting the trailer to power. Just one of those long experience inbuilt safety processes. Don't do dumb s***. Don't do stuff that might be dumb s***. There more that I don't know then there is that I do know. I don't want to learn everything the hard way.

 

[Bohemian]

That is one way to put it. I hate it when I say to myself, "I knew when I did it that I should not have........" "Woops"

Amen!!! And I still do it too often.