| the-plumber wrote: | > Doug McLaren Wrote: | > | > The NiCds dropped as expected when they hit the 'knee', but the NiMh | > drop-off curve wasn't a curve, it was a cliff.
Strange. NiCd looks pretty `cliff-like' too once you get below 1.1 v/cell.
| > I'd be real money that if your model was flying when the NiMhs reached | > the end of the discharge 'plateau', you wouldn't have enough charge | > left to land unless you were about to touch down anyway.
Well, the problem with this bet is that `plateau' isn't very well defined. But either way, let it go down to 8.5 volts (when the alarm goes off), you don't have much time left, NiCd or NiMH.
The two spec sheets Red gave for AA NiCd and NiMH cells give relatively similar discharge charts for around 300 mA discharge rates once you take into account the different scales in the graphs. (And it's important to consider similar discharge rates ... things look different at higher discharge rates.)
| hah. Funny that just as I was reading this, I went out to fly a little | model on my no 2 TX (futaba FF6, NiCd cells)...and it started out at | 9.6v.
It should have started out at around 11.0 volts.
Either it wasn't charged properly, or one of your cells has shorted out. Or both.
| Withing 30 seconds the tranny was beeping and showing 8.2v. 30 | seconds later it was 8.1v.. | | The model which was being tested after repairs, came in OK...and the | tranny is now on charge. It got a ten minute flight a week ago and now | its flat, | | Nicads won't keep charge at all..unlike LIPOS. I want LIPOS in may | transmitters PLEASE Mr Futaba.
The 14MZ comes with a LiPo or Li-ion battery. And yet it still only lasts a few hours, since it uses so much power.
NiMH cells do self-discharge a good deal faster than NiCd cells. But even with NiMH cells, a week or two of idleness after a full charge should still leave you with plenty of juice for flying. Beyond that, I'd strongly suggest charging. (And I always charge RX packs at most a day or two before flying -- you don't have a nice gauge or warning bell to tell you when it gets low ...)