28 replies to this topic

[BBZ]

Thanks for all the replies.. 

 

Now, how do I do it.. haha..  

[Advmoto18]

Yes, one can charge a house battery with a 4 or 7 pin connection.

 

But, not really a good idea for a standard equipped vehicle.

 

If your truck came with a single alternator, without any additional options for a travel trailer or camper, then you will be asking a lot of your alternator if wanting to charge house batteries.

 

First, an alternator in single installations is designed to maintain the crank battery and power the vehicle's electrical bus or distribution panel.  An alternator scales its output based on demand by the bus and condition of the crank battery.  Further, an alternator produces constant voltage for charging, 13.5 - 14.5.  Not 3 or 4 stage charging as with "smart" battery chargers.  As such, internal temperature of the alternator can stay relatively high for an extended period of time while charging vehicle and house batteries and powering the bus/distribution panel.  Heat is the enemy of the stator in the alternator.  Operating at a high temp for an extended period of time will ultimately lead to early failure of the stators.  While the alternator operates at a constant voltage, resistance in the electrical system determines the amperage output of the alternator and its operating temperature.

 

For this reason, many of the HD domestic trucks provide for a second, or dual, alternator setup.  Such a setup reduces the load on both alternators allowing each to operate at lower internal temperatures.

 

In dedicated overland vehicles, upfitters will often install a second alternator wired to a dedicated distribution panel for the travel trailer/camper house batteries/electrical system.  

 

For the purposes of the OP, with his small electrical demand in the camper, going through a 7 pin would be the easiest method.

[wildlife2019]

I use the factory 7 way rv power feed.  I spliced in another line (with appropriate rated dpdt* switch) from the plug feed so that I can isolate it if I should need to charge the trailer from time to time instead of 35ah agm batt. that's in truck bed.  I use it for the one LED dome light under cap that burns less than 1ah, and one fan-tastic endless breeze ~3ah, and one phone charge socket. 

 

With such a small load I'm putting on this relatively inexpensive battery, I have had no problems getting 6+ years running like this.  Trust me.  

 

To repeat what others have stated.  Isolating it from your vehicle battery could save you future worries of being stuck.

 

*using it as a spdt switch in actuality

Edited by wildlife2019, 03 February 2019 - 04:16 PM.

[craig333]

Like advmoto said, you'll get a constant voltage (check it with a volt meter to be sure ) which is okay for a bulk charge but for adequate battery "life" you should put it on a good smart charger whenever you can.

[Machinebuilder]

Let me throw a flag on some of the info in the last couple posts.

 

On newer vehicles the alternator is not putting out a constant voltage. they have a battery management system built into the vehicle electronics that lower the voltage.

 

I used the trailer connector from my 2011 F150 to my Granby, and it was adequate charging for using the lights in the camper.

 

When I added an Engel fridge I found out about the vehicle BMS. I don't know if it would have ever recharged the house battery adequately.

 

That's when I added solar, which is great.........until I went camping for a cold rainy weekend. 

 

I'm still working out a good reliable way to keep the hose battery charged with minimal driving and minimal solar, and be able to run the heater and fridge for more than 1 day.

[Vic Harder]

Even with the onboard BMS in newer trucks, when you add the house batteries into the equation, the BMS now "sees" the combined battery status and will adjust itself accordingly.  To do that well, it needs to have the two batteries as "close" together as possible.  Not talking just distance here, but distance and wire gauge = perceived distance (or voltage loss if you like).    

 

Machinebuilder, I wonder if a CTEK 250 might work well for you?

[Machinebuilder]

Machinebuilder, I wonder if a CTEK 250 might work well for you?

 

 

I've considered it, I'm trying to get some things worked out and better monitoring installed. I'm kind of busy at work and the early darkness this time of year has really slowed my progress.

[Colorado Mark]

When I ordered my Grandby, I went with the bigger 160W panel.  I really want to be able to rely on what I have but, for longer trips pick up a used Honda EU2000 generator on craig list to take along.

 

I really, really don't want to use a generator but. . . . . 

 

Now you don't have to worry about cloudy days or starting the truck.  I picked one up for $800.  Looks & runs like brand new.

 

Of course you would also now have to carry a spare gas can. I have a 3.5 gal Rotopax. My truck burns gas.  Dump the gas in the spare can in the truck when heading home.

[rando]

Mark,

 

Unless you are planning a lot of time in Alaska or the like, I doubt you will need or want the generator.  I also have a 160W panel and in the Rockies and Southwest, solar and the alternator can easily keep up.   If you do have issues with shading, you may do better to go with an additional portable solar panel.   Lighter, easier and most importantly quieter than a generator. 

 

Congratulations on the new camper, and welcome to the cult!

[Colorado Mark]

Thanks Rando,

 

A portable solar supplement sounds like a much better idea.  Light as a feather and easy to store.  And even though its a Honda, I really don't want to listen to a generator.

 

My wife & I really do not want to take the generator.  That's the whole reason we wanted our Grandby set up like we ordered it.

 

If we wanted to stay in campgrounds or listen to generators, we would have bought a 40' triple slide-out ultimate behemoth with, the fake gas fireplace and marble floors.

 

YUCK!