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Electrical Current Draw

Printed From: r-pod Nation
Category: Forest River r-pod
Forum Name: Maintenance Issues, Tips and Tricks
Forum Description: Have you ever wondered how something works? Found a good way to do something? Discovered the hard way what NOT to do? Share them here.
URL: http://www.rpodNation.com/forum_posts.asp?TID=3488
Printed Date: 28 Mar 2024 at 7:35am
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Topic: Electrical Current Draw
Posted By: podsible dream
Subject: Electrical Current Draw
Date Posted: 06 Sep 2012 at 3:35pm
Many folks have wondered about the real numbers behind the amount of electricity needed to supply an R-Pod and what in needed to keep the battery up to snuff.  This is especially critical during a "dry camping" expedition.
Becasue we often camp in state parks without AC hookup, i decided to get a monitor and see what was actually happening, electricity wise.  We have a dual six volt deep cycle array in series so it delivers 12 Volts.
 
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 - ~13.6 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 surprising 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 (current draw by the lighted switches and the thermostat.) Fortunately the campground had shower facilities.

I will continue to monitor the power consumption over time 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 in parallel. 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!   
 
 
Walt


-------------
Chris and Walt
'10 RP 171 'Free Spirit'
'13 Durango Crew 5.7l Hemi



Replies:
Posted By: BSAJim
Date Posted: 08 Sep 2012 at 8:38pm
Walt,
 
Thanks for the fantastic post! I am guessing that you may be a fellow engineer.
Wink
 
I have converted the lights in my 177 to LED arrays, and seem a massive chance in electrical consumption. I have not yet found an LED replacement for the outside light with a bayonette mount.
 
I am in the midst of convering the unit over two a dual 6-volt battery system, as we boondock almost all the time.
 
Double panel solar array going in next. My calculations indicate we should be able to go 2 weeks before needed a boost from the Toyota.
 
If you want a shocking current draw, measure what it takes to move the popout on a unit like the 177. We always move the popout while connected to the Toyota to save the r-pod batteries.
 
Jim & Carmen
 


-------------
Jim & Carmen - San Jose, CA
r-pod 177 and V-6 Highlander


Posted By: bhamster
Date Posted: 09 Sep 2012 at 1:15am
Originally posted by BSAJim BSAJim wrote:

I have not yet found an LED replacement for the outside light with a bayonette mount.

We got this one in warm white:

http://www.superbrightleds.com/moreinfo/tail-brake-turn/1156-led-bulb-single-intensity-45-smd-led-tower/526/ - http://www.superbrightleds.com/moreinfo/tail-brake-turn/1156-led-bulb-single-intensity-45-smd-led-tower/526/

It works amazingly well and only uses 290ma. It's pretty pricey, but they also have one with less led's:

http://www.superbrightleds.com/moreinfo/tail-brake-turn/1156-led-bulb-single-intensity-18-smd-led-tower/163/ - http://www.superbrightleds.com/moreinfo/tail-brake-turn/1156-led-bulb-single-intensity-18-smd-led-tower/163/


Posted By: podsible dream
Date Posted: 09 Sep 2012 at 6:45pm
Thanks, BSAJim.  Actually I was trained as a molecular biologist, ended up as a lab furniture sales and lab design person, now retired as of June.
The double solar array should be a lot more efficient in CA than it is in our forests out here.  Let us know how it works out.
Remember that the true draw is an amp-hour number, so if the slide is only powered out once, the effect on the storage battery shouldn't be that great.

Thanks for the tip, bhamster, we'll check it out.

Walt


-------------
Chris and Walt
'10 RP 171 'Free Spirit'
'13 Durango Crew 5.7l Hemi


Posted By: headcold
Date Posted: 04 Oct 2012 at 9:26am
Anyone have a product name and a source (probably Amazon) for the LED light arrays with which I can replace the current ones in my 2011 R-Pod 172?


Posted By: bhamster
Date Posted: 04 Oct 2012 at 9:36am
Are you looking to replace the interior lights? If so, these are the bulbs we used (in warm white):

http://www.superbrightleds.com/moreinfo/miniature-wedge-base/194-led-bulb-6-smd-led-wedge-base-dac/213/ - http://www.superbrightleds.com/moreinfo/miniature-wedge-base/194-led-bulb-6-smd-led-wedge-base-dac/213/

I'm sure you could find something similar on ebay for less, but the reliability on these has been great.


Posted By: podsible dream
Date Posted: 04 Oct 2012 at 8:59pm
I got our LEDs on eBay.  I searched for "621". Ours are 10 diode paddle or racket shaped.  Somewhat whiter than the incandescent bulbs, but the difference is not noticeable when they are the only light source.  Pack of 10 postpaid from China for $30. So far they have been quite hardy and reliable.

-------------
Chris and Walt
'10 RP 171 'Free Spirit'
'13 Durango Crew 5.7l Hemi


Posted By: Little Sweet Pea Pod
Date Posted: 05 Oct 2012 at 12:00am
I have looked at several, bought a set on Amazon and paid more than I should. These a fellow RV'er purchased on EBay. I tried in the Pod and bought same. Warmer "white" light. Some LED's produce a blue-ish light. 

http://www.ebay.com/itm/150871814286




Posted By: Tomcamper
Date Posted: 08 Oct 2012 at 7:33pm
Chris & Walt you did us driers a big favour with those numbers. Thanks how many watts are your panels please???

-------------
Tomcamper
2016 4runner
Dreampod 177

06 GMC Envoy


Posted By: podsible dream
Date Posted: 08 Oct 2012 at 8:10pm
Hi Tom.

I have two 30 watt panels.

Walt


-------------
Chris and Walt
'10 RP 171 'Free Spirit'
'13 Durango Crew 5.7l Hemi



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