Take DIY Off Grid Energy Control to the Next Level

Off grid energy control just got easier.   Currently, I use a low power laptop to log and do some rudimentary control of the power system.  Drawbacks are it requires 120V.   I can turn the house off and turn it back on when the laptop battery gets low.  The generator is turned on/off via AUX relay using voltage set points and other basic controls provided by the Outback's MATE and FlexNet devices.  Another AUX relay is controlled by another voltage set point, timer and wall wart and another relay to drive the generator block heater.  I have a manual override switch to turn the block heater off if we expect to get power through solar or wind.  Is there a better way to get more control?

The Raspberry Pi would be a good next step, but I need a rock solid solution.  Introducing the MotherBone(TM)PiOne(TM) motherboard from APlus Mobile, Inc. (System Reference).

There are an amazing amount of features on this board.  Pair the motherboard with a Beagle Board Black (BBB) and you have an amazing low power supply and controller that can snuggle right into a 24V off grid power system.

With the data logging system, nominal power use is about 76W.   Bringing the house down to minimum levels at night and during the days, I can reduce the load to about 22W.  That is a 70% savings during non-peak utilization and I can still log data and turn the power back on when needed.

Another smashing feature of this board is on-board USB ports and five, FIVE!, solid state relays.  With the BBB and some fancy Python programming, we can use the relays to improve our current situation above (or even geek out and go nuts with more relays).

Example Application

MotherBone(TM)PiOne(TM)+BBB+Linux+Python

Outback Mate (ver 1/serial) + FlexNetDC

USB #1: Mate serial input (logged by python): Shunt and battery voltage data.

USB #2: Outdoor temperature sensors (4 channel DS18S20)

USB #3: Indoor temperature sensors (4 channel DS18S20)

Relay #1: Replace the Mate AGS on/off.  We can now throw this relay when we know the block heater has been running for a predetermined time.

Relay #2: Replace the block heater circuit.  Turn generator block heater on/off.

Relay #3: Override for on-demand heat.

Relay #4: Dump load on/off to heat trace to water tank.

Relay #5: Vent fan on/off for generator shed.

Now we have full control over generator functions.  Instead of doing some funny business with the Mate's AGS settings to pre-heat the generator before it turns on, we can actually do the programming.  When the voltage is low, turn on the block heater.  After two hours, turn the block heater off and turn the genset on.  After we are done charging, turn the genset off.   We can go further, depending on the outdoor temperature, vary the amount of time needed to pre-heat the generator.  If it is darn right balmy outside, we can just turn the generator on.

The generator shed does get warm!  Now we have a relay and temperature sensors to turn the fan on and off in the shed.

During the winter, we occasionally have to dump extra power.  For now, it just is dumped to a heater in the garage.  We can MANUALLY, plug in a heat trace to our water tank to absorb some of the load or AUTOMATICALLY with the new control system.  For this relay setup, we use the low power relay from the MotherBone(TM)PiOne(TM) to drive a high power relay (RIBU1C).

What is relay #3 doing?  Heating systems typically use low voltage 24 V AC and thermostats to provide an "on-demand" signal to the burner control.  If the thermostats are set at 70F, when the temperature falls, the thermostat will send a "demand" signal to the burner by closing a relay on the 24V AC circuit.  Should we have a way to detect that power will be coming in the future and we want to delay the heater from coming on, we can use a relay to "break" the circuit -- temporarily overriding the "demand" signal to the heater.  If it gets below a lower set point, say 65F, then we can turn the relay off allowing the heater to turn on.  So, this relay on the 24V AC we would be using the N/C function instead of the typical N/O function.

Let's get this board on the market so we can play!  Kickstart it today!

Catching up

The snow has since melted off the grill, but it was a great layer cake of snow for the longest time:

Snow on the grill

Recent sunrise

Felt skirt and tie-dye experiment on scarf

By the way, we had sun come into the house today! First time I've seen that since November.

New stove

Here's a picture when I still had hair:

Kate and Rob with hair

 We got a new wood stove, big enough to heat the whole house from the downstairs. Monday the chimney sweep came and gave it a clean bill of health - better than the old one upstairs.

Kate and the new wood stove

The scarf look

Smile for the camera

 In the pictures above you can't see the whole scarf, but the colors are better than the image below. I made this scarf in grad school with a friend who wanted to learn batik. We spent many joyful hours with melted wax over a sterno fire. We also learned a lot about color theory, this being yellow and turquoise dye. The designs are from a Chinese paper cut book I just adore.

Whole scarf

 The fan really is turning:

Stove as the star

Update

Well, it's been an interesting month, for sure. What's going on is that three days before I went on that flight over the Chukchi Sea, I went to the doctor with a cough and fatigue. The cough is most likely due to my blood pressure medicine (ace-inhibitor cough), but only crops up when I'm otherwise unwell. I used to get that cough in the spring before I took vitamin D regularly.

Anyway, the fatigue and tachycardia (fast heart) were more alarming to the PA I saw. She had me get an EKG, then a chest x-ray. The x-ray showed a mystery mass in my mediastina (between the lungs, behind the breast bone). The next week I got a CT scan and a biopsy of the thing - lymphoma. It's the most treatable of cancers, but by the time I met the cancer doctor, another lymph gland was acting up, next to my neck. A week later I had the surgery to put in a Power Port for giving me chemo and the first of the chemo treatments.

I'm in for four chemo treatments, spread three weeks apart, then another PET scan in Anchorage to assess what's what, then possibly two more chemo treatments. Yes, that's up to 18 weeks of "chemo brain". I'm on Family Medical Leave, trying to get a little work done from home each day.

It has been suggested that we set up a Caring Bridge site for all of this:
http://www.caringbridge.org/visit/katehedstrom/

More about the trip

First, a sunrise picture from home:

 Second, someone was asking for more on the science of flying over the Arctic. We flew to Pt Lay, then turned north, dropping radiosondes as we went (turn off your Bluetooth!) The second one got stuck, so someone had to take apart the launch tube.

 Back together! The next six went without a hitch. We flew to 73 N, then turned around. The chief scientist said that if anything, we should have gone farther north. He was looking for how the atmospheric boundary layer changes as the air comes from the south and hits the sea ice. With 50 miles of pancake ice in the marginal ice zone (MIZ), the air was still seeing the water underneath. So we didn't get far enough into the solid ice. They'll get another chance this coming week.

 Once we turned south, that's when we alternately flew above the boundary layer (roughly 5000 ft) and just above the surface (200 ft), with slow transitions between for measuring the turbulence through the boundary layer. Once we got back south of the ice, they let out a few AXBT's for measuring ocean temperature profiles:

The plane has a lot of sensors and each science station has a Linux computer with access to the incoming data. The chief scientist set me up with a display with a few of his favorite inputs, including altitude, wind speed, and a radar sensor which was designed to measure surface wind speeds based on the wave state. The latter turns out to be a good way to see the ice edge even through clouds.

Sea Ice at Last

Over twenty years ago I was sucked into a sea ice modeling project. We didn't do a great job then, but nevertheless we're still in the business. I've thought maybe I should go out and see some sea ice, but it just never happened - until today. Today I got to go on a NOAA P3 flight over the Chukchi Sea, all as a day trip from Eielson Airforce base.

I took a lot of photos, most of them terrible. Here are a few that almost might pass for tolerable:

Over the Brooks Range, running away from the sunrise.

At the northern extent of the flight the ice was thin first-year ice, mostly solid with some openings and thin spots.

Fresh ice.

Flying South into more broken ice.

Farther South the ice is pancake ice with swells from the South.

Winds are strong and it shows over open water.

Swells casting shadows.

Back over land, North of the Brooks range.

Science is done so I got to sit up front for a few minutes.

An interesting river.

View of fog

We got up this morning for our last Adopt-A-Highway pick up of the season. From our house, it was a lovely morning:

Above the fog

As you might guess, by the time we got to town, we were in the thick of it. It even started drizzling by the time we cleaned up our mile.

This afternoon I went by the dye garden to cut off the rest of the tansy. It goes to seed, dies, and becomes stiff stalks cluttering the bed if left alone. So I cut them all down today and left them on the grass for the botanical garden people to deal with.

On the Fiber Factor front, I'm resting this round out, but challenge five will be announced next week. Meanwhile, people have been asking me about notes for the challenge three sweater. I finally got them rounded up (with a few new photos) and you can download them from http://www.ravelry.com/patterns/library/unexpected-angles.