After 20 or so flights and no problems, the engine just quit on takeoff and going vertical.

I measured the ignition voltage before takeoff at 4.99 VDC (4 cell).
Even though the manual says do not fly below 5.00, I decided to try it.

Bench check at 4.85 volts ... ignition still worked. Will it fail at 6000+ RPM?

Anyone have any experience/thoughts.

The Good News ... the EXTRA 300 is repairable (almost complete).

Four cell battery? What capacity is it, perhaps it is too small?

If I were you I would get a fast charger, so that next time you can just charge it up compleatly before flying.

RickP

MustangFan:

It is my understanding that the faster the engine (RPM's) the more current it will draw from the battery. A regular 4-cell battery rated at 1200Mah and fully charged should give you almost 2 hours of flight time with a single piston engine such as a BME50 or DA-50. Twins (such as a 3w100 or DA100 and bigger) will obviously draw more current and you would want to provide a bigger battery (mah).
It could be quite possible that under 5 volts the ignition would fire, but as RPM's increased the spark would either get weaker or be non-existent. This may have caused the engine to quit. As suggested, if your putting in a long day at the field a quick or fast charger would help keep the packs voltage and Mah up to normal. Better to be safe than dead-stick!

Are you using a NIMH battery pack? They have a tendency to drop voltage under load quite dramatically. A pack testing at 4.9V even under load from a volt meter could drop very quickly to 4.3 volts at 500 ma (an engine running up for take-off). That drop is not instantaneous, so you can be fooled by a quick (2-3 second) voltage check. If you can, try and simulate the load your system will put on a battery pack. This is easy to do with an ignition pack as you know the maximum likely load (from the manufacturer). Then keep the voltage meter attached for 10-20 seconds and study the voltage drop. I suspect that if you had done that, you would not be repairing a model right now.

Everyone is correct ... don't fly under 5 VDC.
The voltage range is ... not below 5.00 and not above 6.00.

I'm using a NiCd battery and the current draw is not stated in the manual. But it's hard to keep a 4.8 4 cell above 5.00 and a 5 cell is too high without a regulator. It's funny they would pick 5 to 6 volts as a standard unless they expect everyone to use other battery types.

I have a quick charger (Sirius), used it after every 2 or 3 flights, but not that time.
Maybe I'm tempting fate? Maybe I will go to 5 cell with regulator.

I have an E-Mail to DA, maybe they can give more info.
But they have not been good at answering E-Mail!

I know the newer ignitions can run on 6 volts. I use a 5 cell pack with no ill effects. You may want to give them a call. Once you get a hold of them they will be more then helpful.
RickP