Electrical Current Draw

I mentioned last week that I would show some measurements of the electrical current draw from the battery of my pod while we were 'dry camping' this last weekend.

I installed a Watts Up meter from rc-electronicsusa.com that I purchased on Amazon for about half the list price. The unit is quite small (2.8x1.7x.83 inches) and rugged with four leads - two red and two black. I installed according to the three lead RV installation in the on-line instructions (the unit comes with a brief foldup sheet, but the on-line information is much more detailed.) I added a simple pushbutton (normally closed) switch from Radio Shack for the reset function. I installed the unit on the facia below the kitchen between the monitor panel and the 110V duplex using a 2" piece of sticky Velcro.
Because the unit measures current draw, it is necessary to use fairly heavy wire to connect it (although the leads are only 14 gauge, they are covered with hi-temp silicone). I went overboard and used #6 wire to connect to the negative side of the 12V system. This is the white cable from the battery in my pod. I joined the black source lead to the cable using a large bolt style joiner from Home Depot or Lowes. Then I routed the negative lead from the battery that was connected to the bus bar on the floor (all those White wires!) to a double hole bus bar connector screwed to a small block of wood on the floor. Then connected the #6 ga lead from the unit to it. The other -output- lead from the meter was connected to another piece of 6 ga with a bolt type connector and run directly to the original white bus bar. I then connected the red source lead to the switch and the other side of the switch to a 12V line I installed for an additional 12V outlet in the dinette area - no real current draw here so I used a 20 ga hookup wire. All the wires were run inside the sink cabinet into the converter compartment. (With a 177 or other model, it would be necessary to mount the unit in a different spot.) When I reconnected the battery - the meter lit up and started recording!! No smoke!! No flames!

The meter has 8 readings:
Amp-hours (0-65 in 0.01)
Watt hours (0-6554 in 0.01)
Amps (0-100 peak in 0.01)
Watts (0-6554)
Peak Amps
Peak Watts
Minimum voltage (in 0.01)
Voltage (0-60 in 0.01)

Reset with the button puts accumulated readings to 0 and restarts accumulation.

The voltage readings are the highest voltage detected, so if you are charging the battery, the meter reads the input charging voltage - ~13.66 for the on board converter and the same if the TV is used to charge.

Some numbers for our Pod - we use the Pod sparingly - spending most of our time outside - we didn't have the dome this weekend because the site geometry didn't allow it, but we had a screened canopy over the picnic table that served as our living area.

We set up camp at about 4:30 on Friday afternoon, using the frig on propane for the trip. We used our LED lights and the water pump for filling dish washing basins and flushing the toilet, the frig was on and the LP detector. By Saturday at 7:00 PM, we had used just over 12 Amp Hours of electricity. By the time we broke camp at about noon Monday we had used about 27 Amp hours of juice. I plugged in the TV for about 45 minutes each on Saturday and Sunday to top of the battery charge, although the voltage never dropped below about 12.35V.

Usage-

LP detector - about 0.11 A (1.3 W)
LP and Frig on propane 0.13 A (1.7W)
Water Pump - light on switch 0.1 A (0.2 W)
Water pump under load - up to 6.5 A (~80W)
9 ea 10 LED lights (all on) 0.9A (11.2 W)
Bath incandescent (631) 0.21 A (2.6W)
Porch Light (Yellow) 1.27 A (15.9 W)
Bath Fan on Low 0.75 A (9.3 W)
Small clip on 12V fan 0.35 A (5.5W)

All the numbers include having the LP detector on. What is surprizing is the draw of the porch light. No wonder a car battery will die quickly with the parking lights on!

The large draw by the water pump is not really scary as it looks, because the pump is only used for very short periods of time and not continuously. we did try to turn off the water pump and the water heater between mealtimes to save electricity. Fortunatly the campground had shower facilities.

I will continue to monitor the power consumption over timw to get an even better feel for it. I will report on any changes or other information.

By the way, i did get a second 30W solar panel and hooked the two panels together. we did get enough sun on Saturday, even in the deep forest we were in, that I was able to pump in 13.5V or so for about 2-3 hours - not much- but proof of concept, and it did keep the batteries at a constant voltge for the duration it was plugged into the system.

Wow - that was quite a seminar!   

Podsible / I replaced my outside yellow light with an led from ebay, I think it was $8.00 I could not find the chinese web site that I got my interior lights from, heck you can turn it on for 4 hours and its barely warm, has to be a big reduction in draw on the battery. I did upgrade our battery to a group 27, we have not yet dry camped as we have not been put into that position, p.s. I like my t.v. and my andy griffith dvd's and two and a half men dvd's and my a.c. thats what happens when you get over 60.