Wednesday, August 31, 2011

Solar Dryer Ideas

A dryer is just a heater and a motor to tumble the contents.

Looking for alternatives around my home:
Heat Sources:

Motion Sources:
Fridge Waste Heat Too small
Mains Elec Motor Prob ok, low watts
Solar PV Heat Too expensive
Hand Crank Convenience
Solar Radiant Heat Need a site close to house
Solar pump Too complex
Gas Heater Waste Heat Minor Gas smell?

Electric Heat Currently the problem

Thinking about it some more, our gas heater outside discharges a lot of waste heat, so it's the candidate. And it runs on days when you can't use a clothesline.

A small idler motor run from mains power or DC would be ok as it would need only 50 watts or so. Thats not a lot out of the 4000 watts our dryer uses.

I think it would be convenient to make it so the washing basket becomes the tumbler. I hate hanging up washing on lines, which I suspect is why some people use dryers on sunny days. And lots of everyday items come out good enough to not need ironing. The device would need to be ergonomic with no risk of pinch points or combustion if too hot at a point.

You can say 'lazy' - but in the world of management we call this 'efficient'. :P

**Addendum 5/8/11: Looks like Miele has come up with a horribly complex solution - as only the great over-engineers could. Lose further points for integrating it into the building...

Energy Use - typical values at home

We've been thinking of ways to reduce our dryer usage at home - if you look at the biggest item down the bottom you'll see why:

Item Hourly Watts
6 Cree LED Downlights 18
6 Halogen Downlights 50
Electric Blanket 75
Desktop PC 250
LCD TV 300
PS3 350
Washing Machine 350
Radiant 2 Light Bathroom Heater 500
Fridge 750
Aircon (small) 750
Espresso Machine 750
Kettle 1000
Vacuum 1000
Clothes Iron 1000
Microwave 1000
Oil Filled Radiator 1500
Aircon (big) 1500
Clothes Dryer 4000

The above typical values are per hour. Kettles and microwaves look to be high but they don't get used much.

But when it comes to clothes dryers you don't have many options but to use them for a long time when it is wet outside. Searching online results in lots of suggestions to use your clothes line. Which isn't any help at all if it's raining.

it's impossible to find an 'efficient' clothes dryer as they are really a big electrical resistor to make lots of heat, with a small motor to roll the clothes around.

But I have some ideas for later.

What an interesting device - the self powered (wood stove) ecofan

A thermoelectric generator runs a fan that sheds the heat the unit pulls up from the base, via fins.

Tuesday, August 30, 2011

Solar concentrator - parabolic trough

I have been thinking about taking a cheap 10 to 20w solar panel and directing a lot more light to it via a parabolic trough. People seem to be doing this using simple convective liquid cooling and upping the amount of light by a factor of 5 to 10. Here is a company doing it commercially link It's an extreme example - there is a smaller domestic application to be had.

Or flipping the original idea around, it could be that the main purpose of the device is to pump heat via a liquid - using a small integrated solar panel. An easy unit to relocate if cooling is built in too.

I like the idea of a trough over a dish, as is it will track the sun fairly well during the day, and just need monthly angular adjustments of inclination.

I don't want a point focus like a normal parabola, so by using chunky segments on the reflector (could be cheaper to make) I can spread the reflected light over the surface of the panel.

I did some experimenting in Google Sketchup with reflective angles versus the width of each segment on the parabola and came up with the following diagram:
It looks like the rule of thumb is to make the higher ribs about half the width of the solar panel, but lower down it becomes less important, so the same width is ok. There is a portion directly below the panel that will be shadowed.

Here's my concept:

Solar concentrator - linear reflector

This would be very easy to do - place a cheap reflective surface below fixed panels.

The incidental sun hitting the cheap reflector would direct extra energy to the panel. Extra light would be gained in the morning/afternoon as well, due to reflection of angular light.
Extra light can cause extra heat/inefficiency, or even damage, so the amount would need to be tested.

Some folks online seem to be directing up to 5 or 10 times the light without damage.

Monday, August 29, 2011

Four Bed Rotation Gardening

I created a new file from all the info I had - I keep losing my references. And when I have space to plant and bags of seeds piled up it gets hard to remember what-to-put-where.

Now I can print a copy and put it up in the greenhouse. You can click for the larger version, right click to download.

Sunday, August 28, 2011

Lithium Batteries for bike lights

samdidgaf - Lithium Batteries for bike lights - A'ME heated bike grips

I still have a lot of these old Nokia batts. I soldered three into series (see my other warnings below!) and hooked it up to my hacked bike light (a 4 watt downlight globe inside the orginal bike light).

I got about 15 minutes use before it cut out - but I don't know how well the frankenbattery was charged. I'll give it a full charge and hook it up to my 30 dollar wattmeter and see.

Just this morning I read about the A'ME heated bike grips and thought it would be easy to make bike handle heaters with a few of these batteries, some resistance wire and a motor speed controller to regulate the current/temp.
Might give it a try.

Saturday, August 27, 2011

The solar powered hothouse

I've now got a 40W solar panel and a charge controller ready to boost the light into the evening, I just need to find a battery and hook it all up. Probably heading into the wrong time of year but why not do it anyway.

But what we have planted so far has been really taking off!

Sunday, August 14, 2011

Mum, I bought a Bafang

Brought my wife a hubmotor so she can come riding with me and the kids. Speed controller is on it's way.

We'd better find a bike for her too I suppose....
And I'll need to learn to lace a hub into a rim. I hope youtube can oblige.

Saturday, August 6, 2011

Soldering mobile phone batteries

There are lots of warnings online about doing this - 99 percent of which come from other warnings about doing this. Viral behaviour.

But they aren't without caution - lithium fires happen.

I had a lot of old mobile phone batteries to waste, a 25 watt soldering iron was perfect for joining them up in parallel. I'm hoping they will make a nice range extender battery for my bike if not discharged too fast....

Keep a big bucket of sand handy - if you do try this  - at your own peril.  No liability accepted.

30 volts, ten ampere hours in theory.

Friday, August 5, 2011

Rebuilding my Aprilia Enjoy - Voltmeter

I found these cheap voltmeters on ebay - about 4 dolalrs delivered.

They make a nice replacement to the Standard Aprilia LED unit. It makes for a good way to ensure I don't discharge my LiPo batteries past 29.6 volts.

Shown below with the old NiMh battery inserted into the bike - hence the low reading.

I removed the bezel from the new ebay unit, dremeled out a new area inside the old aprilia backing, and put the clear cover back on. Magic.I even added a waterproof switch thru one of the Aprilia's standard bolt holes in the plastic cover - shown with the controller still hanging out....

Putting a high powered LED bulb into the Aprilia's stock lamp

I wanted to put a 12V LiPo (made from 3 mobile batteries in series) into the remaing battery case space for auxiliary power and lights.

It got me thinking about the stock light (the generator makes so much noise). So I bought a cheap 4W LED bulb from ebay (the kind that replace your halogen downlights). Then I hacked the back out of the standard aprilia fitting with some sidecutters to make room.

Then I pushed in the globe and soldered on some leads. The globe was held firm by puting some 1 inch lengths of 2mm rubber coated electrical cable around the perimeter of the bulb and pushing/wedging it in with a screwdriver's tip.
A quick test and the unit is good to reassemble. The unit barely gets warm at all - those LED's produce a lot of light and negligible heat.

Now to mount it on the bike. I'll make up a bigger battery pack and put a switch and fuse in line.