How do the batteries charge when on the road

[curlyfungirl]

We are planning on doing quite a bit of boon docking on our big trip this summer. How do the batteries charge when we are driving? Will we have to alternate staying at a campground with hookups to charge the battery for the next boondock night? We have an inexpensive solar panel that we bought from C W. I think it works best for the phones and little items though.

[diugo]

If you travel every day, the house batteries get most of their charge (the "bulk" part) from the alternator in the MH or tow vehicle. Even a small solar panel will help ensure the battery gets its full "absorption" charge by the end of the day.

If you find you use more battery energy than your alternator and solar panel can return the next day, then yes, you may need to spend a night at a campground to fully recharge every N nights.

Adding additional solar power---assuming you camp in sunny locations---will increase N. With 400W of panels on my rig, my N is infinity :)

[Ken / Claudia]

My 96 and 01 fords had a charge line on the factory trailer plugs, I would think yours does also. When engine is off there is no charge or draw from it. So as stated above when traveling it will charge the battery but, is that enough? to get a full charge. You will need to try and find out. A generator is real nice to have but, having a extra battery or 2 will also help and at much less cost.

[Laredo291OH]

I'm not sure about the Fords, but I know in the GM trucks the wire for charging thru the 7-pin plug has to be hooked up. It's very easy to do, I don't know why GM doesn't, the wire is already run to the front, already has the ring soldered on. You just remove the cover of the electrical box under the hood, remove a nut from a stud and install the wire.

[JRTJH]

Ford has a relay that must be installed in the underhood fuse box. It normally is shipped from the factory in the glove box. Instructions are included in the package. Without that relay installed, no RV battery charging will occur.

Keep in mind that the tow vehicle electrical system will charge the RV battery, but it is a slow charge and will take a very long time to completely charge. If you use your RV battery for a night of camping and deplete it to 60% or so, it may take 12 hours or more to recharge to about 90%. So plugging in your Tow Vehicle at a campground to "top off your battery" and running it for an hour or so, won't get you much recharging. Actually, you'll waste more gas than you will benefit the battery. It's the same for towing 3 or 4 hours, stopping for lunch, using the toilet, a few lights, washing dishes, etc. Once you get back on the road for another 3 hours before stopping for the night, your RV battery will barely have any more charge than it had when you started in the morning.

[Robby9]

I'm not sure about the Fords, but I know in the GM trucks the wire for charging thru the 7-pin plug has to be hooked up. It's very easy to do, I don't know why GM doesn't, the wire is already run to the front, already has the ring soldered on. You just remove the cover of the electrical box under the hood, remove a nut from a stud and install the wire.


My 2011 Chevy 2500HD came from the factory with the charging line connected. I've got no idea why some do and some don't. Mine came with the RV wiring option installed, perhaps that's why but I'm just guessing.

[diugo]

I believe JRTH has greatly exaggerated the inefficiency of the vehicle charging system, but as with everything in life, your mileage will vary.

Using 40 amp-hours per day as a very reasonable usage assumption, the alternator should be able to provide a measly nine amps and get you 90% charged in just four hours of driving---not "twelve or more".

[Laredo291OH]

Hi Robbie,

That's interesting, because my 2010 GMC 2500HD with tow package and snow plow prep needed it hooked up, so did my brothers 2012 Chevy 2500HD with tow package, my wife's 2009 GMC Yukon and a friends 2008 Chevy 1500. Maybe it's a regional think and depends on where the truck was produced.

[Robby9]

Hi to you too Laredo.
I really don't know why my charge line was ready to go when I got it. Maybe the dealer did it on his own? The RV wiring option is different than the "towing package". The RV option includes wiring for a bed mounted 7-pin plug which is taped up inside fender panel. That was the basis for my wild guess as to why mine worked. I was pleasantly surprised since I expected to have to do the hookup myself.

[gepaine]

I also have had better results charging from my tow vehicle (2007 Escalade) than others would think likely. On our maiden voyage, we pulled into Death Valley (no hookups) with two fully charged batteries, but the next afternoon they were at 60%. It was late April so we didn't need the furnace and had kept other usage to a minimum.

Knowing we wouldn't get thru the night without the batteries going dead, I hooked up the tow vehicle and ran it at idle for an hour and a half - after going around and profusely apologizing to all my neighbors. That got it back to 90% and got us thru the night. We did leave that day (two days early) because I didn't want to disturb the neighbors again.

Got back home and the dealer replaced both batteries under warranty. Brand new trailer and both batteries were bad when I took delivery.

[diugo]

The weak link is often the ground line in the tow vehicle, located between the 7-way connector and the chassis. When I got my truck in '02 (used) it was badly corroded at the screw. After loosening it, cleaning it up, and retightening it, my alternator could deliver close to 20A to a badly depleted battery.

[unyalli]

Want to know for sure? Check there is voltage between the white ground and black hot terminals when the truck is running.

http://www.keystoneforums.com/attachments/photobucket/img_90962_0_3097ad1b4c1306c4abed2125c2f2e9ed.jpg

Simpler? Check voltage at the battery with truck and all 12 volt devices off. Should be something in the 12's. Start truck and it should go into the 13's. With a clamp on amp meter you can see how much amperage is flowing.
http://www.keystonerv.org/forums/attachment.php?attachmentid=3858&d=1375958143

[brucem26]

JRTJH stated:
"Ford has a relay that must be installed in the underhood fuse box. It normally is shipped from the factory in the glove box. Instructions are included in the package. Without that relay installed, no RV battery charging will occur. "

I have a 2011 F-250 and was never aware of any such relay. Can you confirm what models/years are affected by that? Thanks.

[unyalli]

JRTJH stated:
"Ford has a relay that must be installed in the underhood fuse box. It normally is shipped from the factory in the glove box. Instructions are included in the package. Without that relay installed, no RV battery charging will occur. "

I have a 2011 F-250 and was never aware of any such relay. Can you confirm what models/years are affected by that? Thanks.
I had to plug in this relay on my 05 F150 but my 12 F250 was already enabled.

Jeff

[labs4life]

I had to plug in this relay on my 05 F150 but my 12 F250 was already enabled.

Jeff

Same here on the 250. Already installed