Friday, September 9, 2016

More lanterns making electricity

Experiment 3 started with me cutting out a plate the same size as the top of a 228E vent. I attached the peltier and heat sink to it and fired the lantern up.

Early results were very good, 1.7v soon after light up. I think the thin steel plate heated up faster, I also got a better coating of heat sink compound on the peltier and on the heat sink.

Unfortunately as the rig got thoroughly heated up voltage dropped to .5, my little heat sink can't shed heat fast enough to keep up with the lantern.

I tried stacking a heat sink on top of the existing heat sink which seemed like it was working at first but in the end just added thermal mass, once the add on heat sink was heat soaked it dropped back to the same .5v I was seeing with just one heat sink.

So I've managed to get the hot side plenty hot, I've got a USB booster that will take anything over .9v and boost it to charge a USB device, the 1.7v I had when I first lit the lantern is plenty, I'll probably need more current but I can get that with a couple peltiers in parallel. What I need now is to keep the cold side temp such that the voltage stays up.

More experiments to come!

Thursday, September 8, 2016

New project

Back in the saddle again...

As if I needed any more projects I've started work on something new. I saw some videos on YouTube of people using peltier devices to charge cell phones. This got me thinking that a Coleman lantern makes a ton of extra heat so why not put that heat to good use.

This is a peltier device, if you put electricity across the two wires it'll make a cold side and a hot side, so it transfers heat from one side to the other. If you work it the other way around, that is apply heat to one side and cool the other it will produce electricity.

Which leads us to:

A Coleman 228E with a peltier strapped to the vent. The outer vent edge shown gets to about 150F. In testing the outside of the heatsink was getting to around 100F. With that temperature difference (delta) the peltier was making around 1/4 volt. Thats proof of concept but not really enough power to do anything...

Experiment two got us more heat, the top of the vent is more like 250F, the ends of the heatsink were now reading more like 120F and you can see in the picture we got around .85v. This is a semi-useful result, I could run several peltiers in series to get a useful voltage but its still disappointingly low. I sprinkled some water on the heatsink and got 1.9v which is a very good result.

This tells me the issue is insufficient temperature delta, the hot side is plenty hot but the cold side isn't cold enough. The heatsink I was using is really small, I've got another much larger one from an old computer case to try next but before I go there I need to make a better system for mounting the peltier and heatsink. Lantern vents are rounded at the top, I really need a flat surface 40mm wide to mount on. I'll work on that next...

Wednesday, September 7, 2016

New Years resolutions down the tube

This year's resolution was to write every day. If you go back to my last couple blog posts you can see I was doing a pretty good job. I wrote a lot of stuff I didn't post too. Then March hit and everything ground to a halt. Its hard to explain why but a really crappy winter with no snow didn't help. Whats surprising is that when I'm busier I actually find time to get more done, when times are slow I get lazy...
In April we had a layoff at work and a couple close coworkers got the axe. That effected me more than I like to admit and made me even lazier.

So anyway its been mostly a summer off, here's something to get us back into the swing:

Angie's 2005 Volkswagen Golf has ugly front fenders, the driver's side especially. It looks like somebody backed into it just forward of the driver's door which caused the lip above the wheel to pooch out. I bought a pair of used fenders from a junkyard that were supposed to be A0 condition. A means good and 0 is supposed to mean zero defects. When I got them I found this:

Of course its the driver's side thats in worse shape.
First I removed the rust:

The bucket is full of citric acid, this is a trick I learned from lanterns and is the same system I used last year on the Dietz wick lantern. It took a couple days before they were completely rust free. Fortunately there was only rust in that corner, it'd have been annoying to build a tub to soak the whole fender.

I welded a patch over the hole which is hidden by the firewall anyway, then I fiberglassed over the whole thing. The fiberglass smooths everything out and covers the weld which is likely to rust otherwise.

Two cans of color match paint came from, I like their spray nozzles but one of the two cans was considerably better than the other. Unfortunately I used that can first. I had to paint the welded section a couple times because I didn't do a good enough job getting the patch perfectly smooth first. I should have scrapped the paint down on the whole fender, then primed and painted but I was trying to go quick and as usual ended up wasting a bunch of time and paint.

You can see the primer on the effected corner. I've already put color on the whole fender which is why it looks dull.
As of today I've got color and clear coat on the whole thing. The clear coat is terrible, it orange peeled like crazy, was very hard to get a solid coat down, like the paint was too thick in the can. I need another can of color but I'm going to try my local Fischer Autoparts and see if they can do better...