Power use testing on my 2013 Hawk

[idahoron]

After getting back from a couple weeks of hunting and camping I decided I needed to get an idea how much power my camper uses. I have a three way fridge in my camper. I have installed LED lights in the sockets. My camper does not have a heater. I do have a Buddy heater (no power) and I have a small electric heater when I am plugged into the generator or shore power.


My camper power use.
The camper with the switch pulled and fridge on Gas mode 270 to 288 watts / 2.3 amps
The test below is the same as above but with lights
1 light 300 to 311 / 2.4 amps
2 lights 318 to 325 / 2.5 amps
3 lights 325 to 328 / 2.6 amps
4 lights 330 to 339 / 2.7 amps
5 lights 343 to 348 / 2.8 amps

This test is with the comfort zone heater
https://www.amazon.com/Comfort-Zone-Personal-Heater-CZ707/dp/B0007ULR14/ref=sr_1_21?s=home-garden&ie=UTF8&qid=1477435575&sr=1-21&keywords=comfort+zone+heater

The camper switch is pulled and the fridge is on.
Heater on low over night setting. The heater comes on and turns off with thermostat .
1025 watts / 8.5 amps when heater is putting out heat. Actual watts used just for heater is 737 watts on low.

The camper switch on, and fridge on. Heater on high MAX 1527 watts, 12.6 amps.
Actual power use when heater is on high is 1239 watts just for the heater.

I know I can't run the electric heater with my battery. How much solar would I need to just keep the camper going with the usage I have?

 

[Vic Harder]

I'm missing something in the math, but that said:

1) You need enough solar to recharge you batteries
2) You need enough battery to run your daily (plus maybe another day or two if no sun is available) power draw.

Help me understand your numbers, please. Worst case is obviously fridge, lights and heater running full tilt for 24 hours. Are you saying the draw in this situation is 1527 watts, which you also measured as 12.6 amps being taken from your battery bank? As I understand it Watts = Volts * Amps, so you voltage would be 1527/12.6 = 121.2? Is it possible that you are running off AC when you measured this?

If so, your Watts will be the same when on DC, but the Amps will be a lot higher. A = W/V = 1527/12 = 127 Amps. Yikes.

Before I go further with that, can you clarify the situation? Have I got this right so far?

 

[idahoron]

I'm missing something in the math, but that said:

1) You need enough solar to recharge you batteries
2) You need enough battery to run your daily (plus maybe another day or two if no sun is available) power draw.

Help me understand your numbers, please. Worst case is obviously fridge, lights and heater running full tilt for 24 hours. Are you saying the draw in this situation is 1527 watts, which you also measured as 12.6 amps being taken from your battery bank? As I understand it Watts = Volts * Amps, so you voltage would be 1527/12.6 = 121.2? Is it possible that you are running off AC when you measured this?

If so, your Watts will be the same when on DC, but the Amps will be a lot higher. A = W/V = 1527/12 = 127 Amps. Yikes.

Before I go further with that, can you clarify the situation? Have I got this right so far?

The heater is a 110 volt like I said I won't be using that.
The actual usage is 300 to 325 watts for evening but 270 to 290 at the least for 24 hours.

 

[rando]

I am not really understanding your numbers either. How are you measuring your power consumption?

 

[idahoron]

I am testing with a Reliance appliance tester.
The camper with the power switch turned on and 3 way fridge on is 270 to 288 watts/ 2.3 amps.
Each light is about 10 watts / 0.1 amps.

 

[rando]

So you are measuring the AC power going into the converter through the shore power hookup? Is the converter also be charging your battery explaining the 270W - 288W draw with nothing on?

 

[idahoron]

I guess that would be a yes. The tester was put on the shore power so I guess the charger wold also be on there.

 

[idahoron]

I just tested again and with the battery fully charged and only with switch on it pulls 100 watts/ .8 amps.
the fridge pulls about 188 watts/ 1.5amps.

 

[Beach]

You will find running the 3 way fridge on 12v will require a fairly large solar system, especially so if you want a fast recharge. Running the fridge on propane when off grid is much more efficient.

 

[rando]

In order to get better measurements that are easier to understand, you may want to try making these measurements on the DC side of things. If you disconnect the negative terminal of your battery (with shore power also disconnected) and insert your multimeter in series in current mode you can directly measure how much current your loads are drawing. I don't know if you have LED lights, but I would hope that your lights aren't drawing 1Amp (@12V) each! In general subtracting two large numbers to determine a small number is a noisy and inaccurate way of making a measurement.

I recently installed one of these:
https://www.victronenergy.com/battery-monitors/bmv-700

Which has made it much easier to figure what is going on in my electrical system.

I guess that would be a yes. The tester was put on the shore power so I guess the charger wold also be on there.

 

[idahoron]

You will find running the 3 way fridge on 12v will require a fairly large solar system, especially so if you want a fast recharge. Running the fridge on propane when off grid is much more efficient.

The fridge is running on 110 power since it is on shore power. I don't run it on 12v because it kills the battery pronto.

 

[idahoron]

In order to get better measurements that are easier to understand, you may want to try making these measurements on the DC side of things. If you disconnect the negative terminal of your battery (with shore power also disconnected) and insert your multimeter in series in current mode you can directly measure how much current your loads are drawing. I don't know if you have LED lights, but I would hope that your lights aren't drawing 1Amp (@12V) each! In general subtracting two large numbers to determine a small number is a noisy and inaccurate way of making a measurement.

I recently installed one of these:
https://www.victronenergy.com/battery-monitors/bmv-700

Which has made it much easier to figure what is going on in my electrical system.

You must have missed something. The lights are pulling, .1 as in one tenth of an amp.

 

[rando]

You must have missed something. The lights are pulling, .1 as in one tenth of an amp.

Sorry, I took your first post to mean that the lights were pulling 0.1A at 120V (mains power), which would mean they are pulling 1A at 12V (which I assume is what they run on). That seems like a lot, the LEDs in my Fleet only draw ~0.2 A each (at 12V). Just trying to help understand.

 

[DrJ]

Ron,

I would think you need very little solar to run your system.
You live in Twin Falls - so there is average sunlight - nothing like our Vegas or So Cali brothers who hog all of the sunlight.

But you are only running a few LED lights and a 3 way fridge.
No furnance, no 2 way fridge, no other electronics.

You are likely to go for several days - maybe 1-2 weeks without needing any recharge off a full battery.

If you had 50-100 watts of solar, I can't imagine that you would ever be out of power.
Even if you had several days of cloudy weather, you should be good.

I camp frequently with 68Siesta and he has almost your same setup. A few LED lights and 3 way fridge.
He goes on 1 week trips with no issues at all.

I'd be shocked if you used more than 10 amp hours a day of power.

 

[idahoron]

Thanks, Sometimes I plug my lap top into the camper too. I was thinking that a small solar set up would work when I don't have my trailer. I almost always have my trailer, but this summer I did do a 10 day trip without it. We drove about every day somewhere and between that and plugging in twice I didn't have any problems. It would be nice to keep it topped off all the time.

 

[Vic Harder]

I'm with DrJ. Add a 100-140w 12v panel on the roof with a trimetric sc2030 and tm2030 and be happy