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Old 05-15-2015, 12:47 AM   #1
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Join Date: Oct 2014
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Battery charging amps

Battery charging amps

I am trying to find out how many amps or watts the battery charger uses in the forest river
A 122 pop up. I want to purchase a generator to charge the battery and small electronics such as laptops and phones on long trips. I have calculated the watts required for the devices we want to charge, but I have not been able to find any information on the what's required by the battery charger.
The plan is to plug the generator into the shoreline power on the trailer to charge everything.

I am hoping that a 1000 W generator will be sufficient.


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Old 05-15-2015, 01:00 AM   #2
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Join Date: Dec 2012
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More than sufficient for charging. You're good to go!

For a stock converter/charger you're going to be looking at around 700-800 watts. Your 1000w genny won't put out the 11-12 amps your converter/charger would like to see, but it will keep ya campin without much of a hassle.

Have fun!

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Old 05-15-2015, 03:09 AM   #3
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Location: Camano Island, Washington
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Your trailer has a CONVERTER that will charge the battery when plugged into shore power OR a generator.
You should have a manual for it in the owners manual paperwork.
A 1000w will recharge the battery but not much else.
A 2000w will run the microwave and should run the Cool Cat a/c if so equipped.
Dan-Retired Firefighter/EMT
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Old 05-15-2015, 03:57 PM   #4
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The stock converter in an A122 is rated at 30 amps output, 12V DC (nominal). That would be 360 watts max output. Allow for losses in conversion, max input is less than 450 watts. There should be a plate on the converter giving the actual 120 volt input (maximum) in either watts or amps.

The converter input is going to vary considerably depending on battery charge level and other 12V loads. When the converter fan is running, power draw is more than 100 watts (a realistic guess based on loads in my A122). If the converter fan is not running, it's drawing less than 100 watts. Very seldom does my converter fan run - when it does the battery is very low and/or the fridge is on 12V DC.

A 600 watt generator will power your converter and recharge a laptop from a 120 volt plug.

As stated in the A-frame forum, a 2000 watt generator will power the Cool Cat A/C (around 1400 watts) plus run the converter plus small loads.

The generator output will decrease with altitude, but the loads do not. A 25% loss at 6,000 ft (Lake Tahoe, Colorado Springs) is normal for a carbureted engine.

Fred W
2014 Rockwood A122
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battery, charging

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