5th Wheel Rig..Is His Truck Engine Charging the House Battery?

[akadeadeye]

A family member has a 5th wheel rig and had a battery problem on a recent trip. To make a long story short, he believes that his pick up truck is not charging the 5th wheel battery in between stops. The battery gave out on them and he knows they didn't plug into shore power for two nights, but he thinks the truck should have charged it up on the road. How can he check to see if the truck engine is charging the house battery?

Don

[Guest BillAdams]

With everything hooked up and ready to tow, check the house battery voltage with a digital voltage meter. It should be in the 12-12.5 volt range. Now start the truck and either set it to a high idle or have someone hold the pedal so you have about 1000 RPM. Measure the battery voltage now and you should see a higher voltage that continues to climb into the 13.5-14V range. If the batteries are very low they might start at less than 12V but you will still see a substantial change in battery voltage with the truck running if everything is connected to allow for house battery charging.

[Guest Wayne77590]

Most trucks are set up to charge the battery, but it will only be charged while the engine is running. A call to the manufacturer of the model he has should be able to tell him what the charging circuits are. It may be necessary to run another wire to the trailer hook-up, and another to the battery.

[deluco]

I have two 12-volt house batteries in series. Do I hook up the trickle charger to both batteries, ie...the negative on one battery and the positive on the other?

Or do I have to charge each of these batteries separately?

[wolfe10]

I have two 12-volt house batteries in series. Do I hook up the trickle charger to both batteries, ie...the negative on one battery and the positive on the other?

Or do I have to charge each of these batteries separately?

Actually, I suspect you have two 12 VDC batteries in PARALLEL (positive of battery one to positive of battery two, negative of battery one to negative of battery two).

Were they wired in series, you would be running the coach on 24 VDC!

And, yes you can hook a trickle charger to the positive terminal of either battery and the negative to the negative of either battery for charging.

Be aware that all trickle chargers are NOT the same. You want one that will maintain the proper voltage (check with digital voltmeter after fully charged-- 24 and again at 48 hours). Voltage, once the batteries are charged should be between 13.2 and 13.5 VDC. Below that means they are not being charged properly, and above that means they are being overcharged/water boiled out of them.

Brett

[deluco]

thank's Brett. Yes they are in parallel. I am running on 12 volts. i appreciate the heads-up on the chargers.

[akadeadeye]

Many thanks to all the replies about my other post concerning a friend's problem with his pickup truck not charging his trailer battery.

Here is an update and I would like to ask if anyone has knowledge about this problem.

He told me the 7 pin plug on his Ford F350 diesel, with a towing package, is the culprit. It is a factory plug. Apparently, the 7th pin (the one in the center) is the one meant to charge the battery, but it is wired to service the backup lights instead. So, the only time his trailer battery is being charged by his truck battery is when he is backing up.

Any thoughts?

Thank you

Don

[wolfe10]

7 Pin Wiring Diagrams:

http://rvbasics.com/techtips/rv-travel-tra...lug-wiring.html

http://www.etrailer.com/faq-wiring.aspx

The center IS back-up lights.

The black is supposed to be 12 VDC positive.

Brett