In this series, I’ll cover several important topics surrounding a power or energy budget. What they are, the benefits of having one (especially off grid), and how to create one. We’ll cover calculated power vs measuring it, make some common power measurements to start our online power database, In the last installment we will offer an online calculator to help do your power budget and save energy! . Part 3 described power measurement. In this installment we present some real data that is helpful in creating your own budget, and selecting your off grid appliances.
If you create a power budget based on the information you can get from appliance and device labels, you may be disappointed in the size or limitations of the power system you need to run them. Its very empowering to have a power monitor like the P4400 Kill-a-Watt to get good information about your devices under normal operating conditions. I used the monitor extensively the last week around our off grid home.
[editors note: The entire series can now be found on our new Power Budgets page for your convenience!]
Since it’s winter and we haven’t had a sunny day for 5 weeks, we’ve been getting power in the genverter mode (no solar help), and I was careful to take measurements on inverter power. In our case the inverter outputs a Modified Sine Wave for its AC output voltage. Just to satisfy my own curiosity, I checked many devices on generator power versus inverter power and didn’t see any real power differences.
Please note the data given in the table below can be sorted by any column, or you can use the search feature to quickly find the device you want.
Power Data you can use:
|Device Type||Model / Description||Watts Measured||Max Watts (label)|
or Volt x Amp
|Test conditions / Notes|
|Coffee||Espresso machine, Hamilton Beach||Espresso Machine|
|Computer||ASUS eeePC 1000 Netbook PC||25W charging|
|12Vdc x 3A =36W||Charging fully discharged battery.|
|Computer||Desktop PC, Acer xx 4GB ram||60-75W avg||110W max measured|
120Vac x 7A ~ 840W
|power when off = 4W|
|Dishwasher||Kenmore||1265W|| Off Grid Dishwasher?|
Full load in water miser mode takes 1.37 KWH
|Game Console||Nintendo Wii||17W||Has instant on feature. When 'off' takes 8W|
|Lights||18W Compact Florescent, 75W equivalent light||15 W avg||18W||15-16W, when warm 15W.|
|Microwave||Goldstar, smaller oven||780W||120Vac x 8.5A ~ 1020W||Heating water for 2 min.|
|Screen||CRT Monitor, 15", old Samsung||70W||no input 60W|
|Screen||LCD monitor, 22"Acer X223w||26W avg||120Vac X 1.5A ~ 180W||off when off.|
|Screen||LCD monitor, 15", AOC brand||63W avg||not on label||no input pwr 4W. any input 52W min. Power switch does not affect power, input or not determines power. Max 100W|
|Slow Cooker||Rival Crock Pot (4qt)||71W Low |
|Ran test in Rethinking Off Grid Cooking |
|TV||Visio 32" LCD flat screen||70W avg||120Vac x 1.6A ~ 192W||90W with no input and blue screen. When TV screen varies from 65-75W|
|TV||Samsung LT2338||42W (high pwr save)|
62W (auto pwr save)
|100W||Max pwr 78W, use the power saving features in setup menu.|
|USB external Disk||WD 'my book' 500G drive||7-10W in use||15W max measured|
12Vdc x 1.5A = 18W label
|4W when USB not plugged in.|
|Wireless Router||Zyxel, 4 port||5W||12Vdc x 1A = 12W|
Measuring the power yielded some surprising results so far. For example, the fact that many electronic appliances had “instant on” features that drew 3-8 watts, even when turned off! I’ll try to arrange some time with friendly local merchants to take my power monitor in their store and collect even more data!
Free power monitor: This table is not fully complete. We need more types of devices and a few brands of each as well. Want to help? I’ll be giving away a Kill-a-Watt monitor to the 25th commenter on this article! Do you already have a monitor and some information to contribute? Great! Just send it to marshall [at] genverters.com. (Contest will end March 1st with a random drawing for comments if less than 25)
March 2nd Update: Congratulations to Arild in winning the Kill-A-Watt monitor!
Next in this series, I’ll offer an online power budget calculator to help you get a feel for your off grid power needs!
What category of electrical device did we miss here? What do you want listed? Enter your comments below!