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I have found puffing for me is a direct result of discharging too low. Just one instance of flying to LVC will result in the lipo puffing about 3-5 cycles later when used in an EDF application. If I happen to go below 3.5 volts/cell at rest then I am in dangerous territory. My ESC is set to its max of 3.3/cell and if I actually hit that and the ESC shuts off in flight, these new high C lipos will not rebound voltage like the old days. They will stay low about 3.3-3.4 not bounce back to 3.7 so if I hit LVC on and EDF in flight I know I toasted the lipo for EDF use. I typically mark the pack then use in a lower C application. If I keep using it in the EDF, the in about 3-5 flights later the pack will puff on me. I have not found any brand lipo that does not do this. So that is why I only fly by timer. I do not know why lipo manufactures do not suggest much higher LVC values these days. It is so easy to kill a lipo C rating by going below ~3.3 volts per cell. I get several emails a week from people who have 40C lipos and yet the ESC keeps hitting shutoff after one minute of flight time and they don't know why, or they get much lower watts than they should, and it always comes down to the lipo.
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I completely agree and only fly by timer too, set for worst case scenarion full throttle for whole flight at 80% of capacity. Sometimes this means I come down with cells at 3.8v or slightly more.
I am still waiting for someone to invent a lightweight coulomb counter with a buzzer of flashing led to warn when a pre-set capacity has been reached. (I know DX8 and other high-end radios have this, I want to see a cheap standalone unit) The problem with high LVC of 3.7V is that a high amp draw will often depress the voltage below this even from fully charged. In that case the LVC alarm would be set off too early. |
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Some time ago I went through a phase in my prop planes of buying larger mah but lower C rating batteries, my logic was this a 2200 30C is 66a max out put but a 3000 20c is nearly there at 60a, the larger battery was in the first instance cheaper as 20c lipos seem unwanted.....and keeping the timer the same or there about I was leaving more % in the lipo. I never had any puff on me but..........my big conclusion was that most cheap to mid range lipo brand C ratings are overstated...they just cant deliver the numbers. So now when I buy lipos I always go a rating above what I need, so buy a 35c instead of 25c for instance.
That has resulted in me having only 1 puffed pack in the last 12 months and that was my fault as I ran it down to 3v in an application it wasnt designed for (was only a small 1000mah pack) Keep the C rating up and as much Volts above the 3.3 as possible and your lipos will live much longer, and that save money in the long run........we all like that. Dave |
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Latest blog entry: ESC Programming and why its worth...
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chuck. |
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Had two more flights this afternoon in 15mph wind. When I landed they were barely warm so I'm throttle managing better. Also the puffing has reached a "steady-state" (not worse, not better). |
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ya, that is the issue w/ these small lipos, it's very easy to see 20 c discharge rate and they dont like it. if u think about it it's much less common to hit these # w/ the big lipos . a 4000 at 20 c is 80amps and 50 or 60 is most likely the amps u would see w/ a plane that would use 1 of this size.
the killer is the min voltage they see under load and although they may be at 3.8/cell at rest ,the under load voltage really drops on the small ones. 1 thing that i do to try to help this is to do my wfo passes early in the flight and tool around toward the end at less throttle. chuck. |
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I use 1300s for the mig and it really settles down.
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Does anyone have any experience with the V2 F-86 ( others) thatBanana Hobby sells. V2 has a gyro. Love to hear from anyone who's tried the gyro.
Thanks |
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I love it, have my gyro set to "pro" so I dont notice it much unless its breezy out, posted a video of the maiden several pages back: https://www.rcgroups.com/forums/show...48808&page=159 scroll down the page you'll see it Joe |
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I have the BH 50mm F-16 and F-22 w/ gyro. Beware: the BS2X that comes with the jets requires some pre-flight testing. The gyro in my F-16 had to be mounted upside down (with the gains and switches facing the bottom of the battery compartment) and in the regular direction (servo prongs facing the rear/tail). Use outdoor mounting tape or servo tape to mount the gyro to the bottom of the battery compartment. i've found that mounting the it near the front of the nose works the best.
The gyro in my F-22 installed normally (right side up), with the prongs pointing to the rear/tail. So, contrary to Pete's video, don't bother mounting the gyro sideways as he says to do. It won't correctly counter the pitch/roll of your plane. With that being said, the gyros ARE WELL WORTH GETTING. Another tip with setting up the gyros: MAKE SURE THE GYRO IS CONTROLLING THE AILERONS/ELEVONS IN THE CORRECT MANNER THAT COUNTER THE PLANE'S PITCH/ROLL!! Luckily, I caught this issue prior to flying my F-16. The gyros were countering the plane's roll correctly, but when I pitched the nose up, it moved the surfaces UP as well. And when I pitched the nose DOWN, the gyro moved the surfaces DOWN. There was absolutely no fix for this other than mounting the gyro upside down. Problem solved. The F-22's gyro did not have this problem, so I undoubtedly received an incorrectly manufactured gyro. Both planes fly absolutely great. The gyro keeps both planes flying level in strong winds and make hand launching fool proof. So if your new to EDF jets or want to improve your hand launches, fly on windy days, etc. I highly recommend taking the time to correctly set up and install the gyros. After flying these, I am amazed that people still buy the larger EDF's with more complicated builds, extensive electronics, junk retracts, etc. They definitely look cool and have slick features, but the bigger EDF's are slower, harder to operate (land) and limit yourself to certain flight venues. For under $100, these are hard to beat. Hope this post helps some of you, happy flying. |
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I'm currently focused on a Freewing Su-35. It requires alot of maintenance but it flys straight and true, no matter what power setting is put in. |
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