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C'mon get on it Roger! it's been months!
![]() I've been using 7S instead of 8S to keep the amps under 100 (my particular het motor kv is closer to 1650 and not 1500 the sticker says it is)so today I finally went and got a ICE2 120HV to replace the ICE100. Tomorrows flights will be somewhat faster!
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Latest blog entry: Durafly Vampire 70mm
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Meanwhile, my F100 is ready for flight. All is in working order. I did a static test, and got only 4.5lb of thrust... I didn't get what was going on, but then I noticed that the afterburner lights were dimming at full throttle. Sure enough, I tried with a battery that was down to 3.5V per cell... New battery still only gave me some 6lb of thrust. I think I flew initially with close to 7lb of thrust (and the plane only weighed 8.5lb). Now the plane weighs 10lb, and I have 6lb of thrust... I still think I'm OK to fly. However, given that this is a SUPPO ESC and not CC, I couldn't download the parameters to see what it was programmed to, so I just programmed it as follows:
- 6S LiPo (18V cutoff) - Auto-throttle range - Soft brake - Hard cutoff - 1 degree (low) timing (they recommend that for 2-4 pole inrunner motors, and the HET has 4 poles) - 8KHz PWM (I might want to change this one). I will next check the power output for the different settings, and start playing with some of them (specifically timing and PWM frequency) Anybody has any insight for these numbers? |
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Australia, VIC, Melbourne
Joined Nov 2006
6,209 Posts
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Dunno about the Soft brake and hard cutoff choices....
You don't really need any brake, and probably not critical but 'nicer' for something to spin-down on its own. Hard cut off would mean a delay in your recognising full power loss at a distance. At least soft cutoff it still flies and you go "Hmm, it is slowing down a bit... must be LVC". But full cutoff could also occur at a time far more critical. I know you can reset it.... but by the time you recognise it.... Soft cutoff you can generally still fly around and land. I guess if you programmed it then it would have calibrated to your throttle range fine... |
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Australia, VIC, Melbourne
Joined Nov 2006
6,209 Posts
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hehe, might be the opposite... crashing due to no motor power before you realise it.
The BEC should never hit too low a power point as it only needs about 7V or so to still give 5v or 6V out. And if your main battery ever got that low.... well, it never would... it would have exploded into a fireball long before that!! LOL eg 6S 1.2V per cell.= 7.2V still.... and the battery would have been frying from excessive depletion LONG before that could ever occur. When LVC cuts in - at soft cutoff - it is triggered because your battery voltage dropped too low, which is occuring because the current demands are too high for its remaining charge level. So going to soft LVC reduces power to the motor, which (via) reduces the current demand, thus volts come up a bit again..... enough so you can fly around at that reduced power for a while longer - to land - whilst not ruining the battery. But you do want to head for landing immediately, as depending on the exact motor/fan combo, and battery type/age etc, you will only get X amount of further power as the battery depletes and gets hotter and hotter. In a way they are "automatically' controlling things for you and all you have to do is get it down ASAP. On hard LVC all power is gone, but you can 'reset' it by going to zero throttle and then back up.... over-riding it. So then the power use is up to YOU. And then it is very easy to over-use the power and fry the battery. Because you yourself have no way to know the true voltage level.. and what any X amount of power use will cause in terms of grief to the battery. You could smoke it quite easily, just because you don't know what state it is really at. I don't know with soft LVC, but you might be able to reset it also - but you would only do that in a real emergency need of a bit more power! So let them do the "automatic" power control, until you truly needed more for some reason. eg Still stuck out over trees or whatever. But still recognising you only want to use that the bare minimum possible. Or else..... you might have more than just a crash.... but also have a burning plane!! hehe |
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I use soft cutoff on planes that can stay airborne at the reduced power level long enough to get it back to the runway and hard cutoff on "bricks". My reasoning is it gives you the best chance to make a safe landing and if that means destroying a battery then so be it.
I use soft on this F-100 since it glides so well, but I'm probably only at 8-8.5lbs. On another note I got a flight in today with 8S and boy it's fast! No meter on it but calculated around 3300W. |
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Latest blog entry: Durafly Vampire 70mm
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hi guys
i have a question about running batts in parallel or series, so here is the question if i have two 3s 4400mah 40c how should i run them to get a 6s and also what mah will it be at?will i still have 4400 or does it add up?never run batts like that before, cheers guys rudy p.s yoram yes i HATE IT ![]() poured some hot water over it and it seems straight but not like before...but still straight,dont think it will cause an issue
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Australia, VIC, Melbourne
Joined Nov 2006
6,209 Posts
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You have to connect them in SERIES and they will maintain their capacity of 4400mAH (NOT add up to 8800mAH).
One +ve RED wire output.... joining that battery's -ve BLACK to the other battery's +ve RED..... and that battery's -ve BLACK is your other output. |
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with the Het 4 pole motors just run it at low timing and 8khz pwm rate, increasing the timing will only increase amps with zero to minimal rpm increase (wont be worth it) 8khz switching is plenty for a 4 pole motor so as long as the motor starts and runs smoothly there would be no reason to increase pwm rate what fsa on the thrust tube are you going with? looking forward to the remaiden
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