li po battery help
03-05-2005, 04:13 PM
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li po battery help
i am looking into moving to li-pos and i wanted to get the GWS 2 cell battery 7.4 volts 1320 mA, I have a CC pixie 7 and a 300 brushed motor in my slow stick the charger that i want is http://www.hobby-lobby.com/chargers_lipoly.htm its the first one, how will i know when the battery reaches the lowest point in the air?
03-09-2005, 09:06 AM
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RE: li po battery help
I am having a serious case of deja vu here. Did you ask this in more than one place? If so, please limit posting a question to once in one forum. If not, I'm just freaking out.
Anyway, that's a good charger for that particular pack, but think for the future: Will you be moving up in the world, with larger packs? If so, you might want to look into a more flexible charger so you don't have to buy twice.
The Pixie 7 ESC doesn't have a programmable cutoff, IIRC, and its default cutoff is too low to depend on to protect your packs. You might want to verify this with Castle Creations, though, as I've been known to be totally off my rocker.
What to do? The simple solution is to use a timer. For your first flight or two, go through a sequence of fly for a few minutes, land, measure the pack's voltage, and repeat. Keep going until you get down into the 3.5V per cell range. At 3.5V, it's a pretty safe bet the cells are down to 3.0V when the motor's running. Add up the times, knock off 10% for an added safety factor, and set your timer. If you find that you've got plenty of power left after a flight, increase your timer.
IMHO, the timer is a great idea. No other form of flying uses an empty fuel tank as a indication of when to land. For full-scale pilots, it's hard on the old bod, not to mention the plane... For "wet power" R/C, it's hard on the plane... Electric park flyers can get away with it only because the planes are so light that they usually won't get damaged in a controlled crash situation.
Anyway, that's a good charger for that particular pack, but think for the future: Will you be moving up in the world, with larger packs? If so, you might want to look into a more flexible charger so you don't have to buy twice.
The Pixie 7 ESC doesn't have a programmable cutoff, IIRC, and its default cutoff is too low to depend on to protect your packs. You might want to verify this with Castle Creations, though, as I've been known to be totally off my rocker.
What to do? The simple solution is to use a timer. For your first flight or two, go through a sequence of fly for a few minutes, land, measure the pack's voltage, and repeat. Keep going until you get down into the 3.5V per cell range. At 3.5V, it's a pretty safe bet the cells are down to 3.0V when the motor's running. Add up the times, knock off 10% for an added safety factor, and set your timer. If you find that you've got plenty of power left after a flight, increase your timer.
IMHO, the timer is a great idea. No other form of flying uses an empty fuel tank as a indication of when to land. For full-scale pilots, it's hard on the old bod, not to mention the plane... For "wet power" R/C, it's hard on the plane... Electric park flyers can get away with it only because the planes are so light that they usually won't get damaged in a controlled crash situation.
