8.4 volt to Li Poly Battery
 

I have a question. If someone can help. I'm fly with a 8.4 volt battery with 300 mah. I would like to try the Li Poly battery. My problem is I don't see 8.4 volts in Li Poly. Everthing is 7.4 volts or 11.1 volts. The motor is a geared 280. It's a little under powered and heavy, but it does fly for 4 or 5 minutes. Will the 7.4 be even more under powered? or Can I go to the 11.1 volt Li Poly battery and run at less than full throttle. Maybe put on a bigger prop? Without damage to the motor or ESC. The plane is a megatech airstrike.

RE: 8.4 volt to Li Poly Battery
 

A 7.4 Volt LiPoly will do just fine. First, the battery is lighter than the NiCd/NiMH it replaces. Second, a "7.4 Volt" LiPoly will read 8.4 Volts fully charged, so the difference really isn't all that huge..

For a Speed 280, a 2-cell Kokam 340 LiPoly pack should be able to handle it. In this case you probably want to save weight, not increase flight time, because the Airstrike is an overweight bird to begin with.

As an alternative, two Kokam 340 packs wired in parallel would give you 680mAh of capacity, more than double of your current pack, and would weigh about the same as your current pack.

RE: 8.4 volt to Li Poly Battery
 

I went down to the local hobby shop to purchase the LiPoly battery. The salesman said the ESC in an airstrike would not handle the LiPoly battery. He said the ESC would probaly run the LiPoly all the way down and destroy the battery. The airstrike electronics are all one big componet including the servos. What do you think? Would it handle LiPoly battery? He suggested just going to 8 cell 9.6 volts NiMgh. Am I wasting my time and money on this plane?

RE: 8.4 volt to Li Poly Battery
 

Yes, the ESC in the Airstrike will probably draw the battery down and ruin it, IF YOU LET IT.

The key here is self-discipline. When you first get the battery, fly the plane for a few minutes, land, and check the voltage. Keep doing this, while keeping track of how long you've flown (total time). When the battery reads 6 Volts, it's time to recharge. Knock about 10% off the total time you flew, and set your timer to this value for the next flight.

Voltage is voltage. The Airstrike's ESC can't tell what kind of battery the voltage is coming from. It won't harf up the battery or burst into a fireball because it's a LiPoly :)

Are you successfully flying the Airstrike in its stock form? If you're crashing a lot, the LiPoly is not a good idea. Crash damage can ruin a LiPoly just as easily as running it down too far.

RE: 8.4 volt to Li Poly Battery
 

Thanks for your help. I can fly the plane without crashing. I really have to stay on top of it. Here lately, can't get it in the air for some reason. I supposed it was the battery. The reason for asking for help. Today I'm trying a 10x7 prop, just for the fun of it. Want to see what happens. Now looking for another plane. Do you have a couple suggestion?:eek:

RE: 8.4 volt to Li Poly Battery
 

Slow Stick - or, if your skills are more advanced, any of the Mountain Models kits (Dandy or Tantrum).

Cheers, Phil

RE: 8.4 volt to Li Poly Battery
 

golfdad - I also have a Megatech Air Strike and am a beginner, at age 59. How did the 10x7 prop work out? I am really looking for replacement props that are cheaper than the $3.00 that Megatech wants, but a prop that provides higher torque would be good. I am also thinking about trying a bigger motor, but that will be in the future.

RE: 8.4 volt to Li Poly Battery
 

golfdad - back to the prop size.....I was discussing a cheaper replacement prop at my hobby shop and the rep found that the Megatech is a 7x6 prop and he speculated that a larger prop would probably not improve the performance of the Air Strike. One thing you might check is the motor and gear box. My Air Strike was stuck in an 80 foot tree for 2.5 weeks through 2 major thunderstorms. I had to lightly lub the motor bushing, WD 40, and replace the gear. I have no problems launching the plane. Good luck and I would like to hear how things turn out on your Air Strike. When I was in Virginia two weeks ago, I had four very successful flights.....on very calm days.

RE: 8.4 volt to Li Poly Battery
 

Larger prop didn't work. I think we have to go a little smaller. I bought a smoothE from Mountain Models. I'm really enjoying RC flying

RE: 8.4 volt to Li Poly Battery
 

I just found this thread...anyway, I got my rc airplane 9 years ago and flew it a few times, then sent it to the closet. I just dug it out and found that it's a megatech air strike. 9 years ago it was manufactured by "enjoy toy and hobby corp," but the plane is the exact same thing I see in the ebay ads for the megatech. I'm going to go for a 8.4v nimh 600mah battery to save weight. I'm also going to put my futaba conquest receiver in it along with some real futaba servos. The stock motor is going to be pitched for a 340, and I'll probablly add a folding prop so I can fly without using the landing gear (weight again). I'm also hoping to add a real wing with some reinforcement since the stock wing bends any time the plane climbs. Golfdad, what did you decide for your battery? Did it work out well?

RE: 8.4 volt to Li Poly Battery
 

No, Never got a chance to go to a different battery. The wing folded on me. Plane hit the ground hard. Bent the prop shaft. Riped open the plastic fuselage. Guess I will part the plane out and sale the batteries and motor.[:o]