Toy off grid system

[jerry1234]

Hello!

A few years ago, I built a nice shed, saltbox style, with insulation, sheetrock, a window & a ceramic tile floor. Having a vague notion that I might somehow get power out to it some day,
I installed wall outlets, switches, and a pair of LED ceiling lamps. All this stuff goes to a breaker
box attached to the back of the shed. But no juice, except for a long extension cord that I can
plug into the house.

More recently, my big UPS ( Uninterruptable power supply ) that protects my Unix server died.
I assumed that it was the batteries, and ordered a brand new set of batteries. Nope, it wasn't
the batteries. With the new batteries, the UPS was still dead as a doornail.

So here I was with two brand new 9 A-H AGM batteries. What to do with them? Electrify the shed! I built a frame out of angle iron stock to hang the batteries under the shed. Obtained
a 60W solar panel and a Genasun MPPT 12V controller. Fabricated an elaborate mount to bolt the
panel to the side of the shed, because I didn't want to penetrate the roof. Bought a Tripp-Lite
inverter for occasional use.

But for continuous use, I just piped the 12V into the shed, to an electrical box, terminating
it in a pair of Anderson Powerpole connectors, where it can do something almost useful and mostly harmless.

That something is backup for my Unix server. I have a small PC that runs off nominal 12V. It's
called a "Giada Cube N3". It's running Slackware Linux. It has a high-sensitivity wifi adapter.
I have written scripts for it so when you power it up, it automatically starts up the wifi adapter and
connects to my main server. The main server has a script that shoves all the important stuff out
to the backup server ( in the shed ). The first time it runs, it takes a long time ( days ). But subsequent runs will only transfer the differences. It will run once a day in the middle of the night.

....So if my house burns down, my data will be safe. Unless the shed burns down too . Being
that the house is fully sprinklered, that's not very likely. What's more likely is that a fire will activate the sprinklers, which will ruin the server with water damage.

It's a fun little project. Involves many hobbies. Welding, electronics, software development,
construction.


P1180334a.jpgP1180331a.jpg

[SunEagle]

Hello!

A few years ago, I built a nice shed, saltbox style, with insulation, sheetrock, a window & a ceramic tile floor. Having a vague notion that I might somehow get power out to it some day,
I installed wall outlets, switches, and a pair of LED ceiling lamps. All this stuff goes to a breaker
box attached to the back of the shed. But no juice, except for a long extension cord that I can
plug into the house.

More recently, my big UPS ( Uninterruptable power supply ) that protects my Unix server died.
I assumed that it was the batteries, and ordered a brand new set of batteries. Nope, it wasn't
the batteries. With the new batteries, the UPS was still dead as a doornail.

So here I was with two brand new 9 A-H AGM batteries. What to do with them? Electrify the shed! I built a frame out of angle iron stock to hang the batteries under the shed. Obtained
a 60W solar panel and a Genasun MPPT 12V controller. Fabricated an elaborate mount to bolt the
panel to the side of the shed, because I didn't want to penetrate the roof. Bought a Tripp-Lite
inverter for occasional use.

But for continuous use, I just piped the 12V into the shed, to an electrical box, terminating
it in a pair of Anderson Powerpole connectors, where it can do something almost useful and mostly harmless.

That something is backup for my Unix server. I have a small PC that runs off nominal 12V. It's
called a "Giada Cube N3". It's running Slackware Linux. It has a high-sensitivity wifi adapter.
I have written scripts for it so when you power it up, it automatically starts up the wifi adapter and
connects to my main server. The main server has a script that shoves all the important stuff out
to the backup server ( in the shed ). The first time it runs, it takes a long time ( days ). But subsequent runs will only transfer the differences. It will run once a day in the middle of the night.

....So if my house burns down, my data will be safe. Unless the shed burns down too . Being
that the house is fully sprinklered, that's not very likely. What's more likely is that a fire will activate the sprinklers, which will ruin the server with water damage.

It's a fun little project. Involves many hobbies. Welding, electronics, software development,
construction.


[ATTACH=CONFIG]5236[/ATTACH][ATTACH=CONFIG]5235[/ATTACH]

Nice little project.

I see two potential issues.

The first is the location of that panel. It looks like it could be in some shade from either that big tree to the right and even from those tall willow looking plants in front. That will reduce the amount of charging time because the panel will just stop even with a little shade.

The second issue is the type of battery you are using. A UPS battery is good for a short time high output power source but is not good for multiple cycles as a true Deep Cycle battery used in solar installations.

[jerry1234]

Nice little project.

I see two potential issues.

The first is the location of that panel. It looks like it could be in some shade from either that big tree to the right and even from those tall willow looking plants in front. That will reduce the amount of charging time because the panel will just stop even with a little shade.

*** It's the best I could do, short of remoting the solar panel. The tall willow-looking plants are
cherry plum trees. We trim them ourselves, and I can keep them clear of the panel. Won't cut them down - we love our cherry plum wine. The big tree is a giant oak, which I will probably have to have trimmed.

The second issue is the type of battery you are using. A UPS battery is good for a short time high output power source but is not good for multiple cycles as a true Deep Cycle battery used in solar installations.

*** Yeah I know. The batteries were basically free, since I had already bought them and had no
use for them. When they die, I'll get a big deep-cycle battery to replace them. Together, they are
18 A-H. I figure if I draw no more than say 2 A-H overnight, they'll have a decent life. 2 A-H * 14V is
28 watt-hours. Assuming that night is 10 hours, that gives me 2.8W. I need to measure the
draw of the Giada. I don't think it's much. It's a teensy little thing.

- Jerry

[SunEagle]

*** It's the best I could do, short of remoting the solar panel. The tall willow-looking plants are
cherry plum trees. We trim them ourselves, and I can keep them clear of the panel. Won't cut them down - we love our cherry plum wine. The big tree is a giant oak, which I will probably have to have trimmed.




*** Yeah I know. The batteries were basically free, since I had already bought them and had no
use for them. When they die, I'll get a big deep-cycle battery to replace them. Together, they are
18 A-H. I figure if I draw no more than say 2 A-H overnight, they'll have a decent life. 2 A-H * 14V is
28 watt-hours. Assuming that night is 10 hours, that gives me 2.8W. I need to measure the
draw of the Giada. I don't think it's much. It's a teensy little thing.

- Jerry

Sounds like a fun project. It would be good for you to track the daily watt hour usage to see how close your calculations come.

[jerry1234]

Sounds like a fun project. It would be good for you to track the daily watt hour usage to see how close your calculations come.

I could do that with this little tiny processor board I bought: a "teensy 3.1". It is a "solution in search of a problem", and so far, has just sat on the shelf. I bought it because it was Just So Cool.

It is a little tiny board, about the size of two postage stamps. It contains a 72-MHz 32bit processor, two 13-bit analog-to-digital converters, plenty of RAM, ROM, EEPROM etc. It also has USB. I could plug it into the Giada there, and have it constantly sample the voltage and current on the bus. To get the current, I'd have to stick
in a small sensing resistor. It would be an interesting project. I was considering to use it to implement an
MPPT controller, but decided to buy one instead.

[Sunking]

What size wires did you use and how long?

[jerry1234]

What size wires did you use and how long?

10 AWG from the panel to the controller, about 10 feet. Hmm, use a copper
table, measure the voltage drop across one leg. According to Wikipedia, it's almost
exactly an ohm per 1000 feet. So a hundredth of an ohm for my 10 feet. It's a 5A
panel, so that gets me 50mV. Have the Teensy take a bunch of measurements fast, toss
out the obviously bogus ones, average the rest. Take the average, call it the final
measurement, send it to the Giada.

If the Teensy was really accurate, I could do it all with voltage measurements - measure
the voltage at the panel, then measure the voltage at the charge controller, do the subtraction.
Don't know if it's that accurate. It has 16-bit ADCs, of which 13 bits are usable. So we divide
the range - call it 40V - into 8192 steps. 4.88mV per step. Damn that's close. Sort of almost
works.

[Sunking]

My bad. Was not asking about the panel wiring, the 12 volt battery wiring to point of use.

[jerry1234]

My bad. Was not asking about the panel wiring, the 12 volt battery wiring to point of use.

*** Four 10AWG wires. Positive, 2 in parallel. Negative, 2 more in parallel. Overkill for the Giada.
But I might want to run ham gear, which intermittently pulls a lot of juice. Another four #10's going
to the inverter, which will be right next to the battery. The powerpole connectors are rated 30A.

- Jerry

[CA_Tom]

*** Four 10AWG wires. Positive, 2 in parallel. Negative, 2 more in parallel. Overkill for the Giada.
But I might want to run ham gear, which intermittently pulls a lot of juice. Another four #10's going
to the inverter, which will be right next to the battery. The powerpole connectors are rated 30A.

- Jerry

In AC wiring it isn't until you get to significantly large sizes that you're allowed to have a double wire. (#2? #0? Would have to look it up)

I don't know if the same rules apply here, but I suspect they would... I don't deal with DC wiring much, so there might be some sort of exception.

[Sunking]

*** Four 10AWG wires. Positive, 2 in parallel. Negative, 2 more in parallel. Overkill for the Giada.
But I might want to run ham gear, which intermittently pulls a lot of juice. Another four #10's going
to the inverter, which will be right next to the battery. The powerpole connectors are rated 30A.

- Jerry

On 18AH of battery? That is not going to work. A 100 watt transceiver will 25 amps. At most you do not want to except C/4 discharge rate on a AGM battery which would be 100 AH minimum requirement.

KF5LJW

73's

[Sunking]

In AC wiring it isn't until you get to significantly large sizes that you're allowed to have a double wire. (#2? #0? Would have to look it up)

I don't know if the same rules apply here, but I suspect they would... I don't deal with DC wiring much, so there might be some sort of exception.

It is 1/0 and it applies to any premises wiring. However this does not sound like Premises wiring.

[jerry1234]

In AC wiring it isn't until you get to significantly large sizes that you're allowed to have a double wire. (#2? #0? Would have to look it up)

I don't know if the same rules apply here, but I suspect they would... I don't deal with DC wiring much, so there might be some sort of exception.

*** this is low power DC on a "toy" system. Didn't ask anybody for permission. Even the
shed itself was built without a permit ( didn't need one, I specifically went down the building department and asked ). I used the #10 because that's what I had. There was a guy at the ham swap that had 100-foot rolls of it for a reasonable price.

- Jerry

[jerry1234]

On 18AH of battery? That is not going to work. A 100 watt transceiver will 25 amps. At most you do not want to except C/4 discharge rate on a AGM battery which would be 100 AH minimum requirement.

Well, I wouldn't want to contest with it, or run RTTY. But the RMS power requirements of ordinary SSB ( if you're not running compression ) are really quite modest. That's
one reason SSB took over from AM in the 60's. I agree, it wouldn't be optimal. The thought
of running ham gear in the shed is only "possibly in the future". The current mission is that low power Unix server.

KF5LJW

73's[/QUOTE]