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Post by rogerthedodger on Oct 10, 2015 13:50:25 GMT -8
"Our alternator wasn't up to snuff." Good to know. Hopefully our Tundra can handle the load. I like the idea of a three way fridge but they're expensive. And the thought of a gas appliance always on in a tiny camper doesn't sit well with me. I read that the 12 volt fridge keeps things cool but not cold. And based on what bpmcgee said above, just the battery will keep things cool for a couple of days. I also read that the hot wire running through the hitch is such low voltage (in comparison to the main truck charging system) that it is more of a low voltage trickle than a full charge. I'd have to drive 12 hours to charge a camper battery. Do you think that's true? True. I put an ammeter inline with my tow line from the alternator to trailer, and it read 1.5 amps. Enough to keep the battery topped off, not enough to run anything. The wire is a very long run from tow vehicle to trailer battery, so the larger the wire diameter, the less voltage drop, hence the more current can pass. After about #12 wire, you run into the trailer connecter pin, which won,t take larger wire. Not the solution for running a refrigerator. IMHO
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Post by rogerthedodger on Oct 10, 2015 13:56:10 GMT -8
NC, If you're using a 7 pin trailer plug and the harness is wired correctly, AND the alternator in the car is up to the job it will. Brian Maybe, maybe not, depends on the length of the wire run from alternator to refrigerator and the wire diameter. See my other post using an ammeter to measure the charge rate.
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bpmcgee
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Post by bpmcgee on Oct 12, 2015 9:48:04 GMT -8
Roger, What you measured with your ammeter is how much the charger was drawing, not what COULD be drawn. When it comes to running electric, in particular DC it seems, I see people ask questions and only get answers that either point out how many variables there are (for instance "remember that your results will change if depending on the length of your run, or the size of your wire, or the material of the conductor") or anecdotes (for instance "Back in '72 I had a fridge -- don't quite remember who made it. And it sucked!") Neither of those two approaches are particularly helpful, so I took a concrete example which I happened to have researched and presented it to give real information. You pointing out that there are more variables to consider isn't helping here To address your point, if you presume that it's a #12 wire for the battery wire (which is the case with the wire I used www.etrailer.com/Accessories-and-Parts/Deka/DW04914-1.html), and there's a 20 foot run from the alternator to the refrigerator, 13 volts at the alternator driving 4.4 amps will experience a 2.28% voltage drop, and will appear about 12.72 volts -- which should be sufficient to drive the refrigerator. B
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Post by rogerthedodger on Oct 12, 2015 12:38:53 GMT -8
I agree, every example is with different variables, and therefore different results. Had your 20' run gone thru a connector which also had a voltage drop, your results may change. My example was a poor one for the refer question because I was referring to a charge line to a trailer battery. Even with a battery that was only at 50% charge, the charge line only showed 1.5 amps. However, if you have a trailer battery which is only at 50% charge, and a refer, your alternator may not be able to run the refer because the discharged trailer battery has placed a larger load at the end of the 20' wire, hence a larger voltage drop, and there may not be a high enough voltage to run a refer. Best way is to try it, if it works, you lucked out.
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bpmcgee
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Post by bpmcgee on Oct 12, 2015 13:00:56 GMT -8
The BEST way to test is buy a $900 refrigerator?
I wish I had the kind of money that would make that the best way for me. I'm stuck with having to educate myself about electricity and do actual calculations and testing and stuff.
B
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