where's the power going?

[mszabo]

Yes. You didn’t say if you were using a inverter?

I forgot to turn off my converter when using my inverter and it just sucked the batteries down.

If no inverter you may want to ohm your heating element. Most likely going to ground.

With converter off or on, you have 12 volts to fringe always.

[semievolved]

Originally Posted by mszabo

Yes. You didn’t say if you were using a inverter?

I forgot to turn off my converter when using my inverter and it just sucked the batteries down.

If no inverter you may want to ohm your heating element. Most likely going to ground.

With converter off or on, you have 12 volts to fringe always.

i have an inverter but it's on a separate circuit straight off the charge controller and i only turn it on when i need it.


for sure there's always 12v at the frig but there's no current running in the feed wires unless the 12v frig switch is flipped on.

[Jon Vermilye]

Originally Posted by semievolved

i have an inverter but it's on a separate circuit straight off the charge controller and i only turn it on when i need it.


for sure there's always 12v at the frig but there's no current running in the feed wires unless the 12v frig switch is flipped on.

That depends on the model of refrigerator. Some don't use 12V at all - they have manual ignition for the propane. Others (such as my Dometic RM 2510 only used 12V to light the propane - the thermocouple held the gas valve open, so once it was ignited, there was no need for 12V.

Most modern refrigerators have a circuit board that requires 12V to run in any mode. It doesn't draw much current (although more when the gas valve is open since it uses 12V for that), but if it isn't there, the refrigerator will not operate, even on 120V.

[DonMa]

I have a 2011 Scamp 13. I run my fridge 8 to 12 hours a day off of three 100W portable solar panels during the summer months. I am in Nevada, lots of sun.

[DonMa]

I started with one 100W portable solar panel. Then decided to add a second 100W portable solar panel so I could power the fridge, without doing the math. My results were similar to yours. Then I did the math and discovered that I needed at least 66% efficiency from the solar panels just to power the fridge. Then I added a third 100W portable solar panel. Now my required efficiency is 44%. Results, outside temps are in the upper 80s to low 90s, inside the Scamp is a couple of degrees warmer, fridge is mid to upper 30s. Plus, I don't have to move the solar panels several times a day and I can charge all of my electronics.

[John in Santa Cruz]

what you need to measure is the voltage at the battery terminals. if thats not at least 1.2V higher than the batteries rest voltage, then the battery WILL discharge under load.

[pngunme]

I camp as remotely as possible.

Personally, I would never rely on solar, to preserve my refrigerated food... unless I was out of propane.

When I go out with my dogs, in my ‘78 FJ40, I don’t carry anything refrigerated... I rely entirely on can goods, Mountain House and packaged foods. We do just fine.

When camping with my Wife, in our trailer, we rely on the refrigerator... on propane. It draws a bit of 12v, for the fridge controls.

As others have said, many variables come into play with RV fridges and their inherent inefficiencies, solar setups and how efficiently your solar set is and how perfectly focused (toward the sun) you keep it all day,
Weather, wiring size (is it optimum for your load), electricity in general, etc.

This article explains a lot... and SunPower RV will answer questions for you. https://www.sunpowerrv.com/can-i-pow...dge-with-solar

Having said all that, this couple thought completely outside the (ice) box and came up with a novel fridge replacement that is much more efficient than absorption fridges... they run their “fridge” entirely off solar
It's Official: The Solar Panels Run Our RV Refrigerator Completely - THE ROAMANS

[Penny in Montana]

I have a question along those same lines. Is it safe to travel with the propane turned on to power the frig! I have been turning the 12v on while traveling.
Penny in Montana

[Glenn Baglo]

Driving with the fridge on propane is as safe as driving your car with gas in the tank.
There is a definite divide in opinion. Many travel with the fridge on propane and have no issues. Some won't travel with propane on, and they don't have any issues either.

[ThomasBalmer]

I have the Dometic 1.9 Cu Ft 3-way, and I have found that when parked, I must be on shore power or propane. When towing, my 160w panel, the tow's alternator, and the 260Ah of trailer battery do it. On my last trip, I discovered that turning the fridge to 12v when breaking camp caused the 12.9 volt trailer battery to show 12.1 volts. That load, 10.5 amps, flummoxed the meters. I'm in the process of increasing the alternator output to not have to worry when towing on cloudy days or in darkness when the panel would add little or nothing.

[Raspy]

Originally Posted by ThomasBalmer

I have the Dometic 1.9 Cu Ft 3-way, and I have found that when parked, I must be on shore power or propane. When towing, my 160w panel, the tow's alternator, and the 260Ah of trailer battery do it. On my last trip, I discovered that turning the fridge to 12v when breaking camp caused the 12.9 volt trailer battery to show 12.1 volts. That load, 10.5 amps, flummoxed the meters. I'm in the process of increasing the alternator output to not have to worry when towing on cloudy days or in darkness when the panel would add little or nothing.

Reading battery voltage, while the battery is under load, does not tell you its state of charge. The battery must be rested to give an accurate state of charge when reading its voltage.

Your alternator is not the problem and putting a larger one one will not fix it. The 12+ wire coming back from the battery to the trailer is too small, or the computer is not allowing it to send current back there.

[Lynn Eberhardt]

Our propane flame blows out when moving. Wiring is insufficient for 12V operation. We travel with an adequately wired inverter in the tow vehicle and run 110AC back to the fridge. On a recent 1700 mile, 10 day trip, using shore power when available and propane when not, original milk was still fresh when we got home.

[ThomasBalmer]

Originally Posted by Raspy

Reading battery voltage, while the battery is under load, does not tell you its state of charge. The battery must be rested to give an accurate state of charge when reading its voltage.

Your alternator is not the problem and putting a larger one one will not fix it. The 12+ wire coming back from the battery to the trailer is too small, or the computer is not allowing it to send current back there.

Raspy,

My charge lines to the trailer are 10 gauge, but the Tacoma 4cyl does not have enough reserve charge capacity to make me comfortable with a 10.5 amp draw. The voltages I referred to were just the fridge drawing off the trailer's battery, not while charging from the Tacoma.

[Ronald W Stone]

Originally Posted by Wayne Collins

[QUOTE…………...
jim, as i said in the OP, i have an in-line meter between the panels and the controller and it was measuring ~180W of power, which would have been more than enough to power the frig and keep the batteries charged.

180 watts at 12 volts is 15 amps. The 12v heating element in the fridge takes a lot of power. You may want to measure the voltage at the terminals on the back of the fridge..
Our 2000 Scamp/Dometic 3-way was showing only 10.5 volts while the battery was at 12v. The Scamp wiring runs all around the perimeter and through the converter. It was too light, had too much resistance.
Solution? run a heavy (12gage) wire direct from battery to fridge. Add a 20 amp fuse in that line.[/QUOTE]

[Ronald W Stone]

I have a large voltage drop from battery to heater. Why? When battery is fully charged : 12.6v; inside 19 ft Scamp meter reads 11.2V and heater will hardly work and for only a short time ? When plugged into 120V heater works fine. Help

[Lynn Eberhardt]

Sounds like something else is drawing power. Is your fridge running on 12V? Possibly a connection loosened. Check the battery fuse holder for corrosion.

[AC0GV]

Originally Posted by Ronald W Stone

I have a large voltage drop from battery to heater. Why? When battery is fully charged : 12.6v; inside 19 ft Scamp meter reads 11.2V and heater will hardly work and for only a short time ? When plugged into 120V heater works fine. Help

You should be seeing no voltage drop when there is no load on. With a single good meter check different points along the wire. You will find the voltage drop. Small wire, bad ground, or bad connection. Also check across all splices. There should be zero volts across a splice, BUT some of the older Scamps are a wire nut rats nest.(Just this note: I recently had 45 OHM and 20 OHM, NEW fuses in a box of Harbor Freight fuses.) To test a blade fuse in circuit , test on the metal contact on the back of the fuse.

[Borden]

Originally Posted by Jim Bennett

Even with my full 320W in the sun giving maybe 50% maximum charge I would never run my fridge off of the 12V system, as I know it will bring the batteries down faster than it can charge them and run the fridge.

One day I travelled with 240W of solar power along with the power from the truck, and it slowly dropped the voltage of the batteries and allowed the fridge to warm up very slowly.

I now will only use 120V or propane to power my fridge. I have used the 12V when running out of propane while I go get some more.

We can only run fridge on 12v while driving between sites it will kill the battery fast. Agree with you on best way to run ammonia 3-way fridge. We pre cool fridge on propane or 110v first and switch it off on stops during our travels.

[jwcolby123]

Originally Posted by wilyoung

There is no such electrical unit as "amps per hour." This, unfortunately, is a very common error. What is it you are trying to describe?

Watts? Watt hours? Amp hours? There is of course amps * hours.

[jwcolby123]

1) The amps coming from the panels is pretty useless. The amps coming out of the converter that they feed is what's important.
2) If your batteries are Lead Acid, then reading the voltage is also pretty useless. Reading the current coming out of the batteries is what is important. Using a shunt going into the battery (for charging) and a shunt coming out of the battery (for discharging) tells you much more than reading voltages anywhere else.
3) There are losses everywhere. Anywhere from 5% minimum to 15% in the solar converter. Charging the battery causes losses directly. Pulling the power back out of the battery causes losses.
4) if the battery voltage is dropping when you feed the refri then the panels are not generating enough power. If they were, the voltage would remain at fully charged voltage.
5) Inverters use power whether or not any load is applied to them.
6) 120 watts is 10 amps at 12v. If you have a 100ah battery, i.e. 10 hours (in theory) although only 5 hours in reality (50%). Run the refri for an hour, turn it off, let the battery rest an hour or so, and THEN read the voltage.
7) I believe you are talking about the refri that uses heat to convert a liquid for cooling. Using electricity for that heat is very inefficient.
8) If you really need to run off electricity then think about replacing the refri with a compressor type. Much more efficient.

Not sure any of this will be helpful.