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Charging Zagi KR-1700AU batteries

The Zagi Trick RC manual says, “SANYO RECOMMENDS CHARGING THE KR 1700AE CELL AT A RATE UP TO 1
AMP….SOME MODELERS REGULARLY CHARGE THEM FOR 40 MINUTES AT 2 AMPS.” This is simply not true. Sanyo’s recommendation is a fast charge of 2.6 amps. That is the exact same recommendation they give for their “fast charging” (4 mega-ohm) N-1700SCR battery, and their “high capacity” (16 mega-ohm) KR-1500AUL. The KR-1700AU has 17 mega-ohms of resistance. I now feel completely safe charging at a maximum of 2.5C… 4.2 amps… a 25 minute charge. I’m staying shy of the often recommended 3C charge because of the fairly high internal resistance in the battery. When I don’t need a speedy charge, I’ll keep it at 1C. I’ll do this for a while and then gauge (mostly by heat build-up patterns in the battery) how to modify this strategy.

See Sanyo.com or my flying homepage for references.

Silicon didn’t help, new motor did

I went out flying today with the spinner held on tightly with silicon glue. It didn’t work. I went through one battery, brought it in, tossed it with a second battery and it only went 50 feet before it started making the spinner’s-gonna-fall-off-any-second noise. FYI: the prop gets quieter and the motor spins faster, making a very quiet high pitched whir as it starts to slip. That’s the sign for you to prepare for a landing and start watching for the prop because then there’s this almost imperceptible clicky-poppy noise when the prop pops off. Now your electric wing is now a glider.

So I took the motor off and tried the Promaxx 7.2 volt motor. I bought this a while ago but never got to try it out. Actually, I’m glad I waited because swapping motors with my new motor mount was a snap… or rather a ‘zip’, pulling the velcro stays off and resoldering (with my snazzy-and-quick soldering gun). The new motor has a bit less power but it flew a LOT longer than the old motor, maybe 20 minutes per battery WOT the whole time! That’s pretty much in keeping with my style so I’m very happy with the new motor. I checked the temperature of the motor after 2 batteries and it was quite a bit cooler than the old motor. My temperature measurement is very scientific: After flying one battery on the old motor, the top of the motor (nearest the prop) was “Ow! I burned myself! [insert finger in mouth]” hot. After flying two batteries on the new motor, the top of the new motor was “Eww. I wouldn’t want to leave my finger on there too long!” hot. Using my handy-dandy temper-lee conversion calculator, those temperatures are 400 and 250 Fahrenheit, respectfully.

Now I have a motor I can rip apart for mad experimentation!

Being eaten alive!

I find myself going out between 5 and 7pm most of the time. The mosquitoes can me AWFUL at this time of the day! Today, I tried dousing myself in DEET bug repellent. Even with the repellent, I had to keep constantly walking around or I’d be chewed on by the bugs! I’ve got marks all over from where those little buggers got me!

A nice day

Julian gave this to me. It’s from several few weeks ago. I suppose I’m a tall fellow by some standards, yes?