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Old Jun 04, 2007, 06:13 AM
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shark7000's Avatar
Lompoc CA.
Joined Apr 2007
14 Posts
Question
Why does my heli not work so well with 8 cell over 7 cell?

I did a search, and came up with nothing. I hope this is in the correct place.
When I got my Walkera #4, it's just like the EF Sabre, with little differences, I noticed when I would fly it with the 7 cell NiMH 7.6volts, it would fly better than when I used the 8 cell 9.6 volts NiMH packs. Why would this be? If I change the pitch on the paddles, I can get it to lift off, but not as good as with the 7 cell. I learned my lesson about using 11.1 volt LiPo on this setup. LOL
So I guess it would do really well with a 2 cell LiPo? 7.4 is quite close to 7.6. So I guessing that is what I should use? Would it also be better just because a LiPo can deliver more power at a high rate? My LiPo's are rated at 10C. What would a 650 mA NiMH be rated as?
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Old Jun 04, 2007, 07:08 AM
Team Mulikow
Gino CP's Avatar
Manila, Philippines
Joined Oct 2006
9,564 Posts
8 cell is heavier. The added power is not enough to make the heli as punchy as the a lighter 7-cell equipped heli. A 7.4v lipo can be ok if paired up with a correct pinion. For FP, that would be anywhere from 10T-12T. Most likely in the 11T region.
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Old Jun 04, 2007, 07:42 AM
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on my falcon 40 which is the same as your walkera i use 7.4 volt lipos when i fly with stock plastic blades and it flys great... when i use flat botton wood blades i use 11.1 volt lipos and thats really fun,lots of head speed,, but dont try that unless you have modded your 4 in 1...................
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Old Jun 04, 2007, 08:10 AM
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PLATINUM's Avatar
USA, VT
Joined Nov 2004
5,802 Posts
Gino is correct! weight of cell is more than the added power.

I had a 620mah 3 cell laying round, and thought I would test it on my hbfp.. I think i got like 15-17minutes out of it. The 850mah cells I use get me 12-15 minutes. Might get more of these 620's
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Old Jun 04, 2007, 02:44 PM
BeeZaur 480
BowerR64's Avatar
Parkville Mo.
Joined Dec 2004
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Quote:
Originally Posted by jacksflying
on my falcon 40 which is the same as your walkera i use 7.4 volt lipos when i fly with stock plastic blades and it flys great... when i use flat botton wood blades i use 11.1 volt lipos and thats really fun,lots of head speed,, but dont try that unless you have modded your 4 in 1...................
Can you explain the mod?
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Old Jun 04, 2007, 06:04 PM
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Lompoc CA.
Joined Apr 2007
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It's hard to believe that the one extra battery makes that much difference in weight.
I tried the 11.1 3 cell on the Sabre, and well, it flew great a few times. It would take off at about half throttle. I had just glued the head set solid, then I loosened it on the bearing with some mineral oil, and it was hovering and responding better than ever. It was on the kitchen table. Any way, one time it was getting too close to the edge, so I set it down, and it fell off the side, and that was it. When I picked it up, the main blades where trying to spin. As I tried to disconnect the battery, I got that famous white smoke. Everything still works but the main motor. Only the IC, or FET I guess from what I've read, is all that is bad.
Here is a thought, maybe it would be possible to use an 11.1 LiPo if you put a resister on it to bring the voltage down to about 8-9 volts. I have a bunch of different resisters here. I am going to see if I can find one that will do this. I'll post my findings later.
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Old Jun 04, 2007, 07:45 PM
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nihms & Nicads are very heavy... nearly double the weight of a lipo.
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Old Jun 04, 2007, 07:47 PM
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Lompoc CA.
Joined Apr 2007
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Quote:
Originally Posted by jacksflying
on my falcon 40 which is the same as your walkera i use 7.4 volt lipos when i fly with stock plastic blades and it flys great... when i use flat botton wood blades i use 11.1 volt lipos and thats really fun,lots of head speed,, but dont try that unless you have modded your 4 in 1...................
Come to think of it, this made me wonder too. My Blade CP 4in1 handles an 11.1 LiPo. Are the other brands not as good? The one on my Sabre and Walkera #4 is only a 3in1, isn't it? I don't really know myself. I never got instruction books with any but the Blade CP. It recommends the 3 cell LiPo upgrade. I put the 2 motors on the tail of the Blade, and it seems too slow in the tail. I adjust it all the way to the right, and it still drifts left. I haven't taken the time to adjust the gain and the other adjustment on it yet. You know what I mean. I guess the trim on the gyro. I've been using these FP heli's to get more inexperience first.

So far, on the resistor with the 3 cell LiPo, it's at about 350K-425K ohms that looks like it would put it around 8.4-9.?. I just need to find one that can handle the 10C battery (max 12C for a few seconds) that I have. Maybe I wouldn't have blown my RX in the Sabre if I was using my 8C LiPo? Does anyone know if this would have been enough to make the difference? Or is it still just too much voltage?
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Old Jun 04, 2007, 07:48 PM
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Lompoc CA.
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Quote:
Originally Posted by PLATINUM
nihms & Nicads are very heavy... nearly double the weight of a lipo.
Now that is one thing I did notice. BIG difference.
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Old Jun 04, 2007, 08:58 PM
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Reno, NV
Joined Dec 2005
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shark7000,

Let me save you some time. Forget the resistor idea and look up the fuse mod.

-JT
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