Sunday, August 20, 2006

Living Off the Grid

A few of you know that I am a bit of a nut with an obsessive dream to build a house that generates it's own energy. Some call it self sufficient living, but I don't think that accurately described what I had in mind as most self sufficient people tend to have long hair, are vegans, smoke weed and live in the desert just outside of Tucson Arizona.
I'm too much of a tech addict to ever de-evolutionize (new word?) to that point.

Well, recently while reading some more about this (read: "feeding the obsession") I came across the term "Off the Grid" which I think more accurately describes the direction I'm interested in.
More importantly, I found a site outlining many of the ideas and concepts I have been thinking of.
It's put together by Glen Hunter, who with his partner started building an "Off the Grid" place in 2002. The house is made of straw, which in my opinion is a whole other issue to "off the grid" but after looking at the progress and final results I must admit I think straw houses are pretty interesting too.
The site Glen has put together outlines many many of the issues and details associated with off the grid living, for the point of view of an owner/builder who also has a 'normal' job (i.e. isn't living off the land and building full time)

Anyway, here is the link to the site. The house is in Canada, and you'll see from the pics they experience 'real' winters of -30deg with good dumpings of snow.
The major 'eco' design factor of the house is using the sun to heat a huge mass during the day, and radiating that heat back at night. On Glen's house this is achieved via a wall of windows, and a bare concrete floor. Even in the winter, the sun streams in and does it's thing. Along with this form of heating is underfloor radiant heating, and (just recently!) a very small log burner. Electrical power all comes from Solar and Wind....oh yeah.

They live over 800m from a possible grid power source, are not connected to it, and living a normal life - that's cool.

I found this site pretty inspirational. Often I feel most people don't quite get it when I mention "off the grid" - this is a great example of what I have been talking about.

The Straw House Blog

My page of interesting links for building a house

Sunday, August 06, 2006

Make an iPod power pack for $7USD

You may have noticed my earlier post with a link to making your own iPod power pack.I can't help thinking it was pretty complex and while it is small, how long would it charge for?

I thought I would put my money where my mouth is and have a go and making one based on something I thought up myself and as I so willingly suggested to a poster on who was looking for an iPod power pack.

The basic theory was to get a Car accessory -USB adaptor, and rip it to bits, combine it with some batteries and presto, have a power pack to charge an iPod away from any usual power source.

So I went to Guang Hua Computer Market today and picked up some bits. As you will see in the photo, I got carried away with various shaped battery holders and cases, and different switches, just to make sure I had all options covered. Here is a photo of everything that I bought, including a soldering iron (80nt - and that wasn't the cheapest!)

Here is a photo of the bare minimum bits you'd need based on a 12v DC input (8 x 1.5 AAs - but you will see I used a different configuration to this)

The final parts list (that I used) is as follows:

1 x Car Accessory-USB adaptor = 90nt
2 x 8AA battery holders = 40nt
1 x rocker switch = 12nt
16 x AA heavy duty batteries = 79nt
1 x Black plastic project case = 80nt

total price = 301nt (including batteries)
total price = 222nt (unit only) About $7 USD!!

First step was to take the Car Adaptor to bits. A blade screwdriver in the seam and it was in bits.
A small sticker on the adaptor stated:
Input: DC 12V-24V Output: DC 5.0V +- 5% Max: 500mA
Wha,wha....what? This handles 24V input? So, after thinking about this for 2 seconds, I figured 16 AAs would be better than 8. Will last longer. :)
After a bit of jiggling around I found that I had to use the 2 long battery holders instead of the 2 flat ones.
I had bought a new LED so I could have a power indicator, as I presumed the one on the adaptor would be in the wrong position. After some testing, I discovered the adaptor LED was a hi-tech 2 color unit that indicated green for 'ready' (input ok) and red for 'charging'. I desperately wanted to keep this feature, so I carefully bent the LED around so it would sit in a hole beside the USB slot in the case.
Next step was to cut the holes for the USB slot, LED and the rock switch.
I positioned these all at one end, using the space not occupied by the battery holders
I used a drill to make some holes which I finished off with a craft knife and needle file. That took the longest time, about an hour for a decent job.
Then it was just a matter of assembling the switch and USB unit, with attached LED into the case. Due to precision hole making, these were a nice push fit.
Then it was a matter of soldering the wires from the battery holders to each other (+tve to -tve) and one to the USB unit, one to the switch, and one between the switch and the USB unit.
I should mention at this point that some web research outlined that the center pin part of those adaptors is +tve.
I melted a bit of excess plastic with the soldering iron to anchor the other end of the USB unit to the case.

Some tape tidied the only wire-to-wire soldering and it was ready for business. I packed out the battery to case void with some polystyrene wedges to stop it all rattling around.
As you can see, it works a treat and it actually looks quite professional too...
The rest of the Photos show: Before the lid goes on.
With the lid on, charging iPod.Red LED indlicates charging.
The complete unit is a reasonable size, but with 24V on board, I am hoping it would be good for a few charges.

220nt for a battery pack for any USB charged device is pretty cheap.
A couple of hours to make it, and I am not into electronics (no kidding, I had to even buy an iron).
Well worth the effort I reckon.

If you were a real geek:
You could put in a external DC input, and a charging circuit. Then you could use rechargable batteries which would save money in the long run, but I figure I wont actually use this unit more than a few times a year MAX so I'll just stick with 80nt worth of once-use batteries.

Some things I'd like to know though....
What sort of safety features would be good to put in there (i.e. a fuse)?
How long will 24VDC for 16 x 1.5v AAs provide charge at 5VDC 500mA max?
What about heat?

Disclaimer: I just built this to see if it could be done, I haven't tested it in any way, so if you want to make one, do so bearing this in mind...