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Old 04-27-2014, 06:18 PM   #1
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Charging Batteries

I have scanned many threads on charging batteries, but the threads don't seem to answer my questions.
1) How long does it take a truck (Ford 2013 F150 with the proper relay installed) to charge up semi-discharged batteries through routine highway driving? Say your batteries are 50% discharged, and you are driving 3-5 hours, will that juice them up again?

2) You are in a campsite with no electric utilities, you have no generator. Can a F150 juice up the battery running on idle? How long to juice up a 50% discharged battery while parked? Is that a frowned-upon practice vs. running a generator?

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Old 04-27-2014, 07:11 PM   #2
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The answer is that the F150 will not recharge the batteries a significant amount in either circumstance you listed. If the batteries are fully discharged (not recommended) driving 7 hours seems to get them back to about a low half charge. If they are half charged to start with they seem to stay that way no matter how long the truck runs. The problem is that there is way too much small wire between the alternator and the batteries to get any significant current flow., And apparently the voltage regulator sees the fully charged truck batteries and not the trailer battery. I gave up and bought a generator. Much better for the batteries and now we can run the furnace on cold nights and recharge in an hour or so. There are probably ways to rewire the truck with #4 wire or to trick the alternator or to use jumper cables or something in the campground but the generator is actually a nice, effective, easy solution to the problem. About 30 lbs for a small one. And much less noise and exhaust than running a truck. We run the gen to charge when we need to and schedule other things like the computer printer and microwave while the batteries are recharging. Maybe every day in cold weather, maybe every 2 days in moderate weather.

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Old 04-27-2014, 08:01 PM   #3
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Typically you would be lucky to get a 5 amp charge rate which means driving all day would not bring a discharged all the way up up but at least you are going somewhere . Running a 2 or 300 horse engine to charge a battery in camp isn't to practical either.
A generator or solar is the way to go.
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Old 04-29-2014, 07:28 AM   #4
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We had our trailer parked for several days. The refrig. running had ran down the batteries to the point that the refrig. stopped working. After hooking up and driving for about 4 hours the batteries finally received enough charge to just begin to activate the refrig. again. I stopped every hour to check during that morning. So after driving 4 hours just enough charge was there to work the refrig. so not very much. This was with factory wiring.
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Old 04-29-2014, 08:34 AM   #5
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If you plan to go without power for more than one night, you need a generator or solar changer; both if you boondock a lot.
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Old 04-29-2014, 10:12 AM   #6
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The only successful main engine charging system I've seen is the type installed on the EARTHROAMER's chassis...

They spec the Ford diesel chassis with (2) large alternators, with the 2nd one dedicated to charging the large AGM house batteries...They also use LARGE size cables from the alternator to the batteries to accommodate high amperage charge rates...

They claim high charge rates at engine idle for the specific purpose of recharging house batt's to supplement solar panel charging...

Normally, using the TV's engine for recharging house batt's is rather an 'overkill' situation - high HP engine being used for small alternator load...However Earthroamer claims 0.5 gallons/hr at idle for house battery recharging, with low noise level of current 6.7Ltr diesel engine, without excess engine wear...

It would be difficult to adapt your current TV's charging system to much more efficient charging for house battery charging w/o a complete 2nd alternator system - except for some larger wire size in the existing rear charging circuit...
Ray & Pat; Morada, CA
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Old 04-29-2014, 12:00 PM   #7
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Typical Airstream two battery setup, two batteries with about 75 amp hours each capacity, total 150 amp hours. If the set is half discharged, you would need to replace 75 amp hours plus 20% (charge efficiency) or 90 amp hours. If you are very lucky, you can get 7 to 9 amps through the charge line. 4 to 6 is not uncommon. Lets call it 9 amps and think positive. 90 amp hours needed, 9 amp charge = 10 hours of driving or idling time to recharge the batteries.

Consider a small generator with a decent three stage converter/charger or a solar system of about 200 watt panel size to keep your batteries up better.
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Old 04-29-2014, 05:26 PM   #8
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Subject has been covered

You might want to visit this thread:

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