An Eccentric Anomaly: Page 6

Ed Davies's Blog

Roof Rethink

Over the last few months I've been having a little re-think on the structure of the roof - not a trivial aspect of an A-frame house.


Bye Bye, Skype

I've cleared out my Skype account and will not be using it further. There doesn't seem to be an obvious way to delete the account otherwise I'd have done that, too. Here's why…


Five Months!

Bleedin' 'el - it's been five months since I last posted about this here plot purchase.


LiFePO₄ Efficiency

Having just carefully charged some LiFePO₄ cells and also just read a thread on the Green Building Forum about battery efficiency I decided to do a little science and measure the efficiency of these cells.


Charging LiFePO₄ Cells with a Maplin N27GG Bench Powersupply


As previously mentioned, I have 10 of these 20 Ah LiFePO₄ cells. They've been in storage for a year and I was getting a bit concerned that their self-discharge might be reaching the point where they'd damage themselves by going under their minimum voltage so I fetched them and gave some thought as to how to charge them.

When I was playing with them before I used the 12 volt gel cell charger which I previously used for glider batteries, basically as a constant current source. This is not very satisfactory as the charger gets quite hot in the near-shorted state charging a single 3.3 volt cell and you have to watch things very carefully to make sure you don't overcharge the cell.

That was for the initial conditioning charge (when you first get these cells you need to charge them to 4 volts first time, then charge to some value a bit less than this subsequently) and for additional playing. Most of the time I was using them on my little solar panels with a Morningstar TriStar MPPT controller.

Inspired by Outtasight I got a Maplin N27GG bench power supply from Maplin in Blackpool while down that way on a family visit. It's in some ways quite cute but in others quite horrible. The first one I had blew up, moderately spectacularly.


Seasonal Sea Ice Variation

There's a certain sick fascination to be had watching the Arctic sea ice disappear over the years. The minimum extent (area of ocean covered by at least 15% ice) happens each year in September at the end of the melt season and it's preceded by a period of speculation as to what the cover will be this year. As well as the overall downward trends in the sea-ice extents there's also, of course, year-to-year variation.

What I wondered was, how early in the year do you get a reasonable idea of what the September extent could be, so I decided to plot a few graphs to have a look. For example, 2012 was a record low year which was preceded by a sudden drop in extent in early June. 2013 has been bouncing around in the same general ball-park as 2012 until the last few weeks where it hasn't followed last year's curve. (See the NSIDC daily graph for whatever's happening now.)


Dunbeath Pictures

While I've been in limbo (there's light at the end of that tunnel) I've been renting a static caravan for the winter in Dunbeath, about 8 km SW of the prospective plot. I've, unfortunately, not got a lot of exercise this winter but when I have it's mostly been walks round this area on sunny days. Here are a few pictures from last autumn and the last week or two.


David Rose Again

David Rose is at it again with this article in the Mail on Sunday. As with last time lots of people have expressed their displeasure at various points. To find this commentary a good place to start is the update to and comments on the post from which the graph at the top of the article was originally taken (here) but replaced with Comparing global temperature observations and simulations, again by Ed Hawkins on the Climate Lab Book blog.

I just want to focus on an answer to one particular point. More...

Limbo Dance

I continue to exist while waiting for the crofting situation with the plot to be sorted out.


Carbon Dioxide and Seawater


In the same Green Building Forum discussion as the previous comments about Stefan's Law, which I blogged about, Tony also made remarks about warming possibly causing the increase of CO₂ in the atmosphere rather than being the result of it. His idea seems to be that warming of the oceans causes them to be less able to dissolve CO₂ so it comes out of solution and bubbles up into the atmosphere.

...and the rises in the levels of CO2 could even be an effect of these rises rather the cause of them were the rises to be due to some other factor.
As the temperature of seawater rises we know that it can't hold so much dissolved CO2 so at least some of it must be a result of that.

I think this is ridiculous. Here's why.