Emergency Power & Solar Tricks
This entry was posted on April 20, 1999.
This tip started out as an email to a friend, and was never sent. The story began after a large storm hit Seattle in 1999, and I lost power at my house. It occurred to me the next day that the power outage, which doesn't occur often in Seattle, made a nice dress rehearsal for the power outage I had expected come January 2000 (remember Y2K?).
Also, as the owner of TheEpicenter.com, I end up being the guy who fields questions from customers. Several folks have asked the same questions, like:
- "What can I do with the power related stuff Epicenter offers?"
- "What can you use a solar panel for?"
- "What's a power inverter used for?"
- "What would you use one of those Power stations for, and how long can you run a laptop on one of those Power plant batteries?"
So, without further delay, read on. Remember that a large chunk of the text below is a narrative that was made in the first few hours of the storm. Photos were taken the next day (in daylight), and that some additional information was added later to round out the story.
So, its 03/03/99 4:32 AM, and I awoke to the sounds of an amazing wind storm. A peculiar glow was coming from the hallway next to my bedroom and I realized that the emergency power failure lights I have installed all over the house were illuminating. I turned to the clock radio to see the time and to catch a bit of news on the radio and realized that it was brain dead from the lack of AC power. I grabbed one of the power fail lamps from its perch (plugged into an AC outlet) following its relentless illumination, got dressed and went in search for my BayGen freeplay radio. After cranking the handle for a minute or two, I tuned to my favorite news station and discovered that I was one of 200,000 homes in the area without power.
My first thought was to get the generator fired up, and then my sleepy brain reminded me of the ridiculously early hour and of my slumbering, unaware neighbors. An unexpectedly early trip to the bathroom guided by a power fail lamp allowed a few minutes of thought to outline my plans for the morning.
I couldn’t help but to think of the hurricane I went through in Hawaii in 1992 (Hurricane Iniki) as I listened to the Seattle winds howl and the vent pipes in the bathroom whistle. It was reminiscent of the sounds the toilet in Hawaii made from the make shift shelter, bathroom home.
I took the power fail light with me as I assessed the tasks I wanted to accomplish and the equipment that I was going to need. After all, there was no way I was going to be able to go back to sleep. Might as well get some work done. Wind storms spook me a bit after my Hurricane experience. I decided to check my E-mail when I realized I had the Epicenter laptop with me. I also realized that I had one of the Power Plant laptop batteries with me (an item that Epicenter also sells), and the cables required to power the Extensa 390 from the battery. It’s funny, but a few weeks ago I had a chance to use the Power Plant laptop battery on a trip to Hawaii for the wedding of a friend. My testing of the battery on that airline trip proved that the laptop would run for over 4 ½ hours on the Power Plant battery, and another hour or so on the internal laptop battery. So here I am, sharing my thought thanks to a fully charged battery. Am I prepared or what?
I logged on to the secure server (thank God the uninterruptible power supply was keeping the server alive), and I downloaded the Epicenter orders. I then realized that I would need to print the orders so I could assess the workload for the upcoming day. I looked at the power requirements of the HP Laserjet 5L printer at my home and determined that I would need 240 Watts of AC power to get the orders printed.
One of the nice things about owning TheEpicenter.com is that I get to take cool new products home to check out. So I guess I’m the best prepared guy around, and if anyone has to go through a power outage I guess I’m the best choice and least impacted. Funny, but I happen to have a bunch of products here at my house that will be useful! Imagine that!
Anyway, my first idea was to use a new product to power the laser printer. It’s something like the power station one (a portable DC power source) but also has a built in 120Watt power converter, a DC outlet, and a light among other features, but the power converter size would not be sufficient to run the printer. I decided I would need a DC power source and a 500 Watt inverter to allow enough head room to accommodate the warm up cycle of the laser printer. So, what to do about the DC power source? Well, my next thought was to use the Power Station one, but they are all sold out and I didn't save one for my own use!. Then I remembered another new product I just brought home a few days ago which has a larger battery than the power station one, and would be able to power the operation for considerably more time.
After rounding up the components and hooking it all up on my kitchen floor, I hit the on switch. Presto! A few minutes later I had all the orders printed.
It occurred to me that this little episode could be repeated for weeks on end should a great disaster occur. Granted, most people don’t need to process orders at 4:30 in the morning in total darkness (except for the light of a power fail light) but it demonstrates that having the right tools available and a little resourcefulness can really make your life a bit easier. I guess I’ll be picking up some additional items from down at the warehouse later today (assuming there is power down there) just in case. And if needed I’ll fire up one of my generators later today.
Also later in the day (when the sun comes up) I’ll be hooking up one of the 15 Watt solar cells to the laptop to recharge the battery. That’s a project I’ve been wanting to do for some time now, the only problem is that I don’t have a battery or butane powered soldering iron to solder the connector I’ll need to the end of the wires from the solar panel.
I remembered that throughout my house there is only one landline phone (in the Garage) that’s not a cordless, and none of the cordless phones function if the base is without power. Several years ago I made a conscious effort to make sure that there was at least one old style phone in the house for this exact reason. Perhaps everyone should also consider keeping an old phone around.
Update: A Note from 03/03/99 6:54:40 AM
The power just came back on. Now all the clocks in the house are blinking except the laptop clock and the battery powered clock that’s connected to the atomic clock in Denver by radio. The house is really cold and the gas furnace just kicked on. I’m sure my neighbors are unaware of the duration of the outage or the intensity of the storm but they are all late for work! Ha, Ha, I like being the boss.
Post-Storm Dialog and a Solar Project
A few days later I completed the project to power the Extensa 390 laptop from one of Epicenter’s 15 watt solar panels
As background, a customer had contacted me about trying to find a solar panel to charge his Extensa 390 (the same one Epicenter owns), and I told him that I thought the 15 watt panel we offered would do the job and that I would look into it. After the storm, I decided that the time had come to try it out. Not only was the panel able to charge the battery, it was able to power the laptop directly by sun power!
The day after I got the panel working, TheEpicenter.com's former accountant (my sister in fact) came up to work on the books for the quarterly tax returns and I provided the laptop for her to use here. Yes, the solar panel was powering the operation much to her surprise. It was fun to be able to show off one of those crazy Epicenter products in operation to my big sister. She has always thought I’m some mad scientist, now with a capitalist spin I guess (in her eyes).
There were some catches on the solar powered laptop project.
In testing the panel under full sunlight and with no load, the output reached nearly 22 volts. The rated output voltage of the panel is 15volts, with a 1 amp draw. So, as power is drawn from the panel the output voltage drops to a reasonable level. If the panel were to be charging a 12 volt battery directly, the initial charge load would be such that the panel output voltage would drop to an ideal charge voltage for a 12 volt battery (about 14.6 volts). However, one always runs the risk of overcharging a battery unless a charge controller or voltage regulator is used. In this case, the panel was not being used to charge a battery directly, it was being used to supply voltage to the internal charge controller in the laptop, so the pulse width modulated charge controller Epicenter offers was not the correct solution (I won't be elaborating on that subject for technical reasons and time constraints).
In the case of this project, the power was being applied to the input of my laptop directly, and the laptop has its own internal charge controller for the internal battery and its own voltage regulator for internal circuitry. I took a look at the rated voltage of the laptop power supply / charger and it was rated at 19.6 Volts DC, and testing of the input determined that the laptop would be happy with input voltages as low as 10 volts or so before it would switch over to internal battery. So, with the data I collected, and knowing a bit about how an engineer builds in margins into the design of power supplies, I was happy with the numbers. Especially knowing that with a slight load on the solar panel, the output voltage would drop well below the 19.6 volt specification for the external power supply for the Extensa laptop. The only question was what the laptop would think of the slightly high input power if it were powered off, the battery was charged, and the solar panel was plugged into the laptop initially when the load was low.
Since TheEpicenter.com had a customer that wanted to buy a modified solar panel that did this task, I chickened out (an Engineering term for knowing everything is "OK," but not wanting to be responsible for blowing up someone else’s stuff), so I added one more protection element in the final design.
In the final design, I added an 18-Volt, 10-Watt Zener Diode to the output of the solar panel. The zener diode serves as a crude voltage regulator to insure that the output of the panel would never exceed 18 volts (that’s below the 19.6 volt rating of the external supply for the Extensa). Although the output of the panel is below this voltage when things are hooked up and there is a load, the zener diode sits there and burns power and insures the voltage is never over 18 volts even if the laptop is turned off and the panel is first hooked up. It’s a cheap bit of insurance and worth my piece of mind.