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rowan Samba Member
Joined: March 18, 2007 Posts: 131 Location: Knoxville, Tennessee, USA
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Posted: Tue Aug 20, 2013 5:35 pm Post subject: How much electricity is actually used? |
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I have a couple of medical devices I need to run from battery power while my wife and I camp. We have been staying only in places with power but would like to stop doing so. How can I determine the actual electrical usage over a night. Is there something I can plug into the wall and then plug her O2 concentrator, for example, into when she goes to bed that will tell the overnight usage?
I intend to add house batteries and solar panels but need to understand how much I need.
r _________________ Rowan
89 Syncro - Juniper Mackenzie
09 Honda Fit - Finnie
17 Ram ProMaster - John Hordle |
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Syncronoid Samba Member
Joined: January 21, 2012 Posts: 1111 Location: Stanford, CA and Bend, OR
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Posted: Tue Aug 20, 2013 5:50 pm Post subject: |
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The device itself should list power consumption on it, either in watts or amps. There must be a label somewhere. You could also look up the device online; I did that for a small coffee maker before purchasing for my Syncro. _________________ '90 Syncro Westy w/GW2.5L |
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rowan Samba Member
Joined: March 18, 2007 Posts: 131 Location: Knoxville, Tennessee, USA
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Posted: Tue Aug 20, 2013 6:10 pm Post subject: |
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Syncronoid wrote: |
The device itself should list power consumption on it, either in watts or amps. There must be a label somewhere. You could also look up the device online; I did that for a small coffee maker before purchasing for my Syncro. |
Sorta. But the number is not very meaningful. One of the devices lists 120 watts but I can run it for three nights (8-10 hours/night) on a old, tired, 60 amp/hr battery through a 400 watt inverter. This should be 10 amps per hr times 27 hours = 270 amps!
I want something that will measure the actual usage. _________________ Rowan
89 Syncro - Juniper Mackenzie
09 Honda Fit - Finnie
17 Ram ProMaster - John Hordle |
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Ahwahnee Samba Member
Joined: June 05, 2010 Posts: 9810 Location: Mt Lemmon, AZ
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Posted: Tue Aug 20, 2013 6:28 pm Post subject: |
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uther wrote: |
...I want something that will measure the actual usage. |
An ammeter in series with the device will measure what it is drawing. A cheap (sometimes free) one from Harbor Freight would be enough to give you a rough idea (I suppose the accuracy of these is suspect but like I said - a rough idea).
If you know the draw then you can work out what it will do vis a vis your battery capacity over a period of time.
I've never tried it but seems you would put the ammeter between the battery and the inverter for the best measurement. |
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nocreditnodebt Samba Member
Joined: September 28, 2012 Posts: 332 Location: Socal
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Posted: Tue Aug 20, 2013 6:30 pm Post subject: |
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Kill a watt
http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU
The listed power consumption on the back of devices is the maximum they can pull, not the average that they pull. While this will be the same on some devices, not all.
Plug the appliance into a Kill a watt, get a reading over a certain amount of time, then do some math, adding 15% for inverter inefficiency |
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SSWesty Samba Member
Joined: August 20, 2008 Posts: 732 Location: Bellevue
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dobryan Samba Member
Joined: March 24, 2006 Posts: 16508 Location: Brookeville, MD
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rowan Samba Member
Joined: March 18, 2007 Posts: 131 Location: Knoxville, Tennessee, USA
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Posted: Tue Aug 20, 2013 7:05 pm Post subject: |
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This is WAYYY out of my league. What I know about electricity is that you plug some widget or the other in, turn it on and it works. If not you try turning it on/off a few times, plug it in somewhere else and if both of those fail, buy a new widget. I have no idea how to use a battery monitor or honestly any electrical tools. I was hoping there was something out there that measured the total amount of electricity used by whatever was plugged into it... and was cheap! _________________ Rowan
89 Syncro - Juniper Mackenzie
09 Honda Fit - Finnie
17 Ram ProMaster - John Hordle |
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rowan Samba Member
Joined: March 18, 2007 Posts: 131 Location: Knoxville, Tennessee, USA
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Posted: Tue Aug 20, 2013 7:23 pm Post subject: |
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This is exactly what I'm looking for - assuming that I understand what it does. I just ordered one.
Thanks so much...
r _________________ Rowan
89 Syncro - Juniper Mackenzie
09 Honda Fit - Finnie
17 Ram ProMaster - John Hordle |
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r39o Samba Polizei
Joined: May 18, 2005 Posts: 9800 Location: San Diego
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Posted: Tue Aug 20, 2013 8:56 pm Post subject: |
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Here's the real killer. Many people discharge their batteries to death via over optimistic guesses at how much power you can pull out of them.
You need to determine your true needs and balance that against just how much energy you can safely pull from a given configuration.
You will likely find you needs quite high actually.
You may consider spots with shore power to be the safe thing to do and hence limit yourself to those places.
For the true story on batteries: http:www.batteryuniversity.com
This energy topic comes up frequently around here, and from an engineers stand point, I see many people who are not nice to their power sources, unless you consider new batteries every year to be OK. _________________ "Use the SEARCH, Luke" But first visit the Vanagon FAQ!
1990 Multivan EJ 22, Rancho trans 0.82 4th, Small Car front AC, CLKs w/ 215/65-16, homemade big brakes 303mm, Konis, Recaros, etc....
Click to see my ads for Cup holders, Subaru clutch fix and CLK wheels (no wheels currently) |
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rowan Samba Member
Joined: March 18, 2007 Posts: 131 Location: Knoxville, Tennessee, USA
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Posted: Tue Aug 20, 2013 9:40 pm Post subject: |
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r39o wrote: |
Here's the real killer. Many people discharge their batteries to death via over optimistic guesses at how much power you can pull out of them.
You need to determine your true needs and balance that against just how much energy you can safely pull from a given configuration.
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I agree. It's the "determine your true needs" part that I can't figure out. O2 generators, CPAPs, and BiPAPs are not the sort of things that are listed on the usual "how much battery power do you need" charts. I can find lots of info about the fridge, various heating options, TVs, radio, laptops, phones, and such.
Does anyone use an O2 generator while camping? Surely we're not the only people who still want to camp with breathing problems. _________________ Rowan
89 Syncro - Juniper Mackenzie
09 Honda Fit - Finnie
17 Ram ProMaster - John Hordle |
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joseph928 Samba Member
Joined: September 22, 2011 Posts: 2114 Location: flagstaff az.
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Posted: Wed Aug 21, 2013 7:21 am Post subject: camping and battery life |
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uther wrote: |
I agree. It's the "determine your true needs" part that I can't figure out. O2 generators, CPAPs, and BiPAPs are not the sort of things that are listed on the usual "how much battery power do you need" charts. I can find lots of info about the fridge, various heating options, TVs, radio, laptops, phones, and such.
Does anyone use an O2 generator while camping? Surely we're not the only people who still want to camp with breathing problems. |
X-2 on the kill a watt, use one all the time. Works great when you are on shore power or hooked up to an inverter. Not so much on 12 volt. Use my solar MPPT charge controller for keeping tabs on my 12 volt system. http://www.ebay.com/itm/20A-MPPT-solar-charge-cont...417601ca97 Been camping in a VW bus-van since 1966 and never heard of someone using a O2 generator. So keep it up, keep camping, and good luck. _________________ 1987 syncro westy tin top sun roof , GW2.3, rear locker, decoupler, Gary Lee tire rack & winch mount, lift, south african grill, big brakes , rhein alloy ,15 BFG AT, Fiamma 10 foot awning ,140 watt rear 85 watt front solar , mppt, truckfridge, automatic fire extinguishing system, tencent oil cooler, And a RMW SS exhaust! - 1971 bug convertible 1776 engine- 2010 Subaru turbo - 1993 Toyota 4x4 truck - 1999 Harley 95 CI, big bore, Andrews cams . Also 80-84- vans. Stock 65 sunroof bug. |
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PDXWesty Samba Member
Joined: April 11, 2006 Posts: 6247 Location: Portland OR
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Posted: Wed Aug 21, 2013 8:07 am Post subject: |
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For devices like you list, given the important nature of them, I would certainly purchase a small generator and not rely soley on battery power. A Honda EUI 1000 can be had for $500 used and would be a wise investment. _________________ 89 Westy 2.1 Auto |
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