EE's during a power outage... - Page 1
Forum section: electronics / general

author: don.r
author_rank: Frequent Contributor
timestamp: November 23, 2011, 03:48:13 am
content: The winter storms have arrived here on Canada's West Coast and it got me thinking what do other EE's and our ilk do during power outages? Do you reach for the nearest battery powered device? Do you fire up a generator and stick two fingers to the weather? or do you take the time to do stuff that does not involve the movement of electrons like read a book, play cards, etc? I tend to go for the battery-powered option more often than not.

author: EEVblog
author_rank: Unknown
timestamp: November 23, 2011, 03:54:11 am
content: My power rarely fails here, maybe once a year at most, and the outage usually isn't long.Odds are my kindle will still work!Dave.

author: don.r
author_rank: Frequent Contributor
timestamp: November 23, 2011, 04:01:35 am
content: Quote from: EEVblog on November 23, 2011, 03:54:11 amCount yourself lucky in suburbia. I live in a fairly rural area and its not uncommon (once every 5 years maybe) to be out for a couple of days. We usually lose power 3 or 4 times a year in the winter for about 3-10 hours depending on the wind/snow. The PVR has a battery backup but that only lasts for about 1/2 an hour.

author: McMonster
author_rank: Frequent Contributor
timestamp: November 23, 2011, 04:39:05 am
content: I'm not EE, but a CS student so power outage is as bad for me. I usually grab the first book lying around in my room I still didn't read. I usually have up to ten such books (mostly science fiction, sometimes something by Stephen King) around so it's not a problem.

author: don.r
author_rank: Frequent Contributor
timestamp: November 23, 2011, 04:45:20 am
content: Quote from: sonicj on November 23, 2011, 03:54:25 amSuch a simple concept! They sell $3500 generators here that run off the gas line. This would be much better.

author: steaky1212
author_rank: Regular Contributor
timestamp: November 23, 2011, 01:06:47 pm
content: power isnt so bad as I know there is nothing I can do - but its so frustrating when internet goes down (is it isp, modem,router,pc)

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 23, 2011, 03:05:43 pm
content: I just connect a stationary bicycle (with an alternator in it) to a battery/inverter setup. It's surprising what you can do with 100W or so. It's hard to find someone in America who doesn't have some fat to spare. And one pound of fat stores as much energy as 150 pounds of nickel metal hydride. (More like 30-40 pounds after accounting for inefficiency, which is still a lot.)

author: sonicj
author_rank: Frequent Contributor
timestamp: November 23, 2011, 07:19:55 pm
content: Quote from: NiHaoMike on November 23, 2011, 03:05:43 pmdo you have a schematic for your generator/charge circuit? where did you find your alternator?-sj

author: A-sic Enginerd
author_rank: Regular Contributor
timestamp: November 23, 2011, 08:36:15 pm
content: At the office - in the last couple years we had one case of a car taking out the transformer that fed our building, another case of a fire that took out a substation. Both cases, since I do ASIC design and EVERYTHING is done on a computer - went home.While at home - I have a wife and 3 kids and own my home on an acre. I'm lucky to ever have time to play on anything electronics related even when there is power.....so no issues there occupying time.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 24, 2011, 02:20:15 am
content: Quote from: sonicj on November 23, 2011, 07:19:55 pmIt's just the (permanent magnet) alternator connected to the battery and inverter. Charge control is done by manually checking a voltmeter. I got the alternator for $5 from a surplus store in Houston many years back.Normally, that alternator is used in a grid tied system, with a step up DC/DC converter that performs MPPT and a grid tie inverter. (That's part of my senior design project.) The typical MPPT voltage for my setup is about 18V when I'm using it, so it doesn't work as well charging a 12V battery (14.4V charging voltage). It's not used much in that mode, so that's not really an issue. And with most modern consumer electronic devices using well under 100W, it still generates enough to run the essentials (LAN hardware, laptop, LED light).The actual MPPT voltage depends on the user. That's not surprising since as with all fixed field machines, the voltage/current from an alternator relate to speed/torque at its input. Therefore, the impedance seen by the DC/DC converter is the electrical equivalent of the mechanical "impedance". Modeling that impedance is easier said than done, so I just experimentally tune the MPPT algorithm. I have got it to settle to a good state when I use it but it doesn't work very well when the other group members use it.

author: Lightages
author_rank: Unknown
timestamp: November 24, 2011, 03:38:51 am
content: For me, there is no such beast as a power failure. I am running full time solar power off the grid, with a generator for backup during maintenance and the rare event I have clouds for more than 3 days in a row.For me, the most important thing that can go offline is the internet. But even then I have a data plan for on my phone which I can use tethered to my computer.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: November 24, 2011, 06:03:51 am
content: Big power outages usually result in an increase in the birth rate 9 months later, except in the case of EEs. It's said that the species will eventually just die out.