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Author Topic: 12v Current Draw Worksheet  (Read 879 times)

TuMadre

  • Posts: 3
12v Current Draw Worksheet
« on: August 14, 2016, 10:54:08 AM »
In preparation for a week long dry camping trip next month, I have been preparing myself for battery usage only for the entire week.

-I installed a battery monitor https://www.amazon.com/bayite-6-5-100V-Display-Multimeter-Voltmeter/dp/B013PKYILS/ref=sr_1_1?ie=UTF8&qid=1471186608&sr=8-1&keywords=bayite+dc+meter.  This shows several parameters, including voltage and total energy used, which can be reset daily to keep tabs on what is is being used, and how much remains.

-I put a switch on the propane alarm for testing only - Safety first, but I wanted to be able to show a draw of zero on the monitor - which did work - with the alarm switched off, the monitor shows no parasitic draw.  I will not be camping with the alarm turned off.

-I removed every incandescent bulb and replaced them all with LED lighting - and I do mean EVERY one - even the fridge, exhaust fan over the stove and the step light. 

-I purchased a 100w portable Solar Suitcase  http://www.eco-worthy.com/catalog/worthy-100w-foldable-polycrystalline-solar-suitcase-p-347.html.  On clear days I should be able to put somewhere in the neighborhood of 30-35 amps back into the battery if my calculations are correct.  If it's rainy or cloudy, I will pull out a small gasoline powered generator, but I'l like to avoid that if at all possible.

After installing my power usage meter and propane alarm switch, I went through the camper flipping switches and turning things on and off - it was very eye opening. Looks like I will be listening to the Stereo more than I'll be watching TV, and I'm gonna hope for warm nights!  I compiled my results into a worksheet (the purpose of this post) to help me determine what I can run (and for how long) on a daily basis. (An odd finding is that double LED fixtures do not double the current draw as compared to a single LED fixture - any ideas on why?)

My meter will show my cumulative watt-hour usage per battery charge (I will only be in the camper about 10 hours per day), so I am hoping you guys can tell me if I have done my worksheet properly.  If not, let me know so I can update it.  I know I shouldn't take out more than 50% of my battery capacity, so I think I have appx. 37.5 amps per charge to work with.

« Last Edit: August 14, 2016, 10:56:38 AM by TuMadre »
2005 Starcraft Antigua 195CK hybrid TT
2014 Jeep Cherokee V6 Lattitude

RVGrant

  • Posts: 2
Re: 12v Current Draw Worksheet
« Reply #1 on: August 24, 2016, 07:47:52 PM »
Where are you going?

I just got an B+ RV with 2 100 Watt solar panels and an LP generator. I am curious how it would do boondocking, but haven't been able to figure out my typical power usage yet.

Let us know how the trip goes.


TuMadre

  • Posts: 3
Re: 12v Current Draw Worksheet
« Reply #2 on: August 30, 2016, 08:13:59 PM »
Going to Triple Tree Aerodrome in Woodruff SC for an RC fly-in at the end of September.  I'll report back on how my figures worked out - I was hoping that some of the folks that are smarter than me  :P would chime in on my figures.
2005 Starcraft Antigua 195CK hybrid TT
2014 Jeep Cherokee V6 Lattitude

JDOnTheGo

  • ---
  • Posts: 395
    • JdFinley.com
Re: 12v Current Draw Worksheet
« Reply #3 on: August 31, 2016, 07:00:38 AM »
Hi TuMadre, it looks fine to me but I'm not seeing a completed worksheet with your "Hours Req'd" estimate.  Of course, that time varies from day to day and season to season.  My numbers are a lot different but for comparison sake, here is my energy budget (http://jdfinley.com/energy-audit-dutch-star/).  I went with a 'worst case' scenario and what I thought would be fairly typical.
JD - Full timer out west
1998 MCI 102 EL3 Revolution | 2010 Wrangler (daJeep) | 650 Watts Solar
My Adventures

TuMadre

  • Posts: 3
Re: 12v Current Draw Worksheet
« Reply #4 on: August 31, 2016, 08:52:51 PM »
Thanks for the link JD - A wealth of info that would have been nice to have seen earlier.  I appreciate the information and i have saved your link.   :)

I have completed a rudimentary audit using my worksheet - and I'm assuming that the math is straightforward and there are no tricks that I'm missing.  Even though I am showing no phantom draw, I have to assume that the monitor draws some current and have left myself some wiggle room just in case.  The most obvious place for me to conserve is on the LED awning strip and the furnace.  I do have a catalytic heater I can use to knock the chill off - and I can always add another blanket.

 
2005 Starcraft Antigua 195CK hybrid TT
2014 Jeep Cherokee V6 Lattitude

JDOnTheGo

  • ---
  • Posts: 395
    • JdFinley.com
Re: 12v Current Draw Worksheet
« Reply #5 on: September 01, 2016, 06:54:34 AM »
Thanks - I appreciate that!  Yes, your numbers look good. These things are an evolution - gotta use it and see how your estimates compare to reality and then make adjustments.  :)

Yea, the catalytic heaters are pretty good when trying to conserve electrical power.  I had Mr. Buddy that I liked but I misplaced it somewhere.
JD - Full timer out west
1998 MCI 102 EL3 Revolution | 2010 Wrangler (daJeep) | 650 Watts Solar
My Adventures

 

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