The View Up Here

Random scribblings about kites, photography, machining, and anything else

“Ya gettin’ deep, man!”

Posted by Tom Benedict on 01/01/2013

One of my favorite quotes from Snarf Quest. One that describes my life way too accurately, way too often.

So here’s the basic problem with any hobby: it’s like user files on a computer. Eventually they expand to fill all available space. I do kite aerial photography. And recently I started flying model airplanes. I try never to think about how much I’ve spent on kites, cameras, and gear for doing KAP. It’s still less than I paid for my entire college career, but it’s more than I paid for any one semester. (I went to a state school.) Still, in terms of sheer enjoyment, the two rank neck-in-neck.

Now model airplanes are starting to take a toll. Ok, ok, so it’s to be expected. Planes will crash (especially if I’m flying them), things will break, and things will get lost (like the propeller that came flying off my plane a few days ago.) I bought new props, new prop adapters, tape, glue, etc. Eventually I’ll have to replace something serious.

Meanwhile, I’m experiencing something else that hobbies tend to do: creep. When I started doing KAP, I found all sorts of reasons to use a KAP rig on the ground, too. This is when gigapanoramas were really catching on. Flip a KAP rig upside-down, slap it on a tripod, stick in an autoKAP controller, and voila: gigapan rig! (And having used an actual Gigapan head, I honestly think an inverted KAP rig does a darned good job for a fraction of the price.)

This time it’s the planes creeping into KAP. Up until a week ago, I had a perfectly good reason not to use LiPoly batteries with my KAP gear: I didn’t have a charger. Lithium chemistry batteries require a lot more care and feeding than the NiMH batteries I’ve been using, which require only a little more care and feeding than plain ol’ alkalines. After a KAP session, all the batteries go in the charger, and get stuck right back in when they’re done. LiPoly batteries need to be balanced. They need to be charged at the right rate. They need to not overheat. They need need need. I was glad I wasn’t using LiPoly batteries for KAP! They’re a hassle!

But with electric airplanes there’s really not much choice. Lithium chemistry batteries are the only game in town that can keep up with the power to weight ratio necessary to get an airplane in the sky. So I got a charger. I got a nice charger. It’ll work on my car’s 12V system, or I can plug it in the wall at home. And it’ll charge batteries with some unholy number of cells in them. So now my excuses are gone. I ordered LiPoly batteries for my KAP rig. And of course I ordered batteries for my video link as well. I’m crawling with the things now. It’s scary.

Oh! But wait! There’s one more catch with LiPoly batteries. If any cell in the battery falls below 2.5V, the whole thing goes kaput. So you have to balance them, charge them only at the specified rate, and you have to monitor the bejeebers out of them to make sure they don’t do anything weird. So today I ordered a bunch of battery alarms. These plug into the balance connector on the battery and monitor each of the cells. If one drops below 3.3V, they let out an ear-piercing shriek. One of these is going in my plane – the thing that started all this. The other three are going in my KAP gear: one for the KAP rig (which will soon use a 2-cell LiPoly battery to drive its servos), one for the video transmitter (a 3-cell LiPoly), and one for the video receiver (another 3-cell LiPoly). My goal? To be careful enough that I NEVER hear any of them.

There. My hobbies are oozing into each other. I’ve made the switch to LiPoly batteries.

– Tom

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