I received a larger battery for my Citabria last night (again thank you). It is a 138mAh battery and boy does it make a big difference. Not only in improved flight times, but in power as well. The newer battery must have a lower internal resistance, because I noticed improved climb rate and brighter lights.

The only downside with the larger battery is that it is larger. Meaning, it will not fit in the charger. Well, I fixed that. By cutting open the charging slot, I extracted the connector and now I can plug anything in!



I also reconnected the lights and swapped the yellow LED on the right for a proper green one. The green LED is not as bright and packaged differently, so it won't really help sorting my plane out from the crowd, but at least it is now running the correct colours.

Canadian Tire of all places sells a must have tool for electric RC builders and pilots. A DC current meter that can measure over 10A. This is a clamp style meter (funny that the site calls is a Clap meter). It retails for $59.99 which is decent enough, but this week it went on sale for $20.99!!! Less than $25 taxes in gets a tool that can measure up to 400A of DC current! (BTW, it needs 2 x AAA batteries - the first time I've bought a meter that did not include batteries...)



I saw Mark from Cellar Dweller use one about a year ago to balance the up / down thrust of an electric heli and it immediately went to the top of my wish list.

So I just picked one up tonight and tried it out. It's no bazillion dollar Fluke(tm), but for $21 it works quite well. Measured the current draw on one of my planes @ 13.6A (11.1V - 150Watts!). (I think I saw a 16A on the first test, but too much stuff was blowing around the shop, and the battery in the plane was not fully charged.)

One a side by side test with an inline current meter (also Mastercraft), the inline measured 3.08A and the clap :-) meter measured 3.2A.

AC current test was measured while my furnace was running. The reference meter was a cheap (picked up on sale for less than $15 taxes in) PowerFist (Princess Auto) AC clamp current meter. It read 40.1A while the Mastercraft read 38.9A.

That's acceptable tolerance for my needs.

So I've been working on my furnace monitoring kit. And now I have basic weather logging enabled. I am fetching climate data from Environment Canada and adding it to a logging tool called RRD. This is a clever fixes size logging data store. It is meant for recording data on fixed time intervals. In my case I'm recording cycle counts, kWh used and outside temperature once every hour. It spits out graphs like this (hourly for 7 days):



I have created a full page to track weekly, monthly and annual usage.

There is a script (furnace.pl) constantly running that pings the microcontroller every second which returns the current status of the furnace (heating or not).

My crontab looks like this:

0 5 * * * /home/me/furnace/logparse.pl
5 5 * * * /home/me/furnace/hourly.pl
10 5 * * * /home/me/furnace/catchup.pl
20 5 * * * /home/me/furnace/enterdata.sh #legacy - generated by catchup.pl
0 6 * * * /home/me/furnace/fetchclimate.pl
5 6 * * * /home/me/furnace/graph.sh
10 6 * * * ftp -inv < /home/me/furnace/ftpscript #upload graphs to flyinglow.ca/furnace

These are works in progress. You can follow my furnace online (a_furnace).
0 0-23 * * * /home/me/furnace/twit.pl #tweet the daily usage up to the hour
0-59 * * * * /home/me/furnace/lcdstatus.pl #update an LCD display (and spin some servos)