esc question
 

:eek:I noticed that the voltage limits on my 25A esc for my 3100kv brushless motor are 9.2v - 14.8v. This does not seem right to me and I've been experiencing problems with motor stuttering and cutting off after only a miute or so. shouldn't the low voltage limit be more like 5v? As the battery starts to drain to 9v and below dropping below the low limit of 9.2v of this esc wouldn't that effect the motor operation. I am not very knowledgeable in electrical theory but it seems like I got the wrong esc for this motor and should have one more like 14.2 or so as the high and 5v as the low. any input on this subject would be appreciated.

RE: esc question
 

No, the ESC cutoff is correct. If your running a 3S1P LiPo 11.1 volt battery and run it to 5v cutoff, your damaging the lipo battery. The issue is exactly where most say the safe low voltage is. Some say 3.2, some say as low as 2.9. At 9 volt cut off on a 3 cell, you above that critical 2.9 volt per cell. I would say keep it closer to 3.2 volts per cell or 9.6 volts. At 9 volts your running border line on damaging your lipo. Also, some ESCs' such as Align, state to only run a fully charged battery every time you connect it. If you run a lower voltage slightly discharged battery, they state you run the possibilty of unsafely discharging below safe voltage due to the ESC thinking its a fully charged battery and taking the percentage of discharge from a the starting voltage. I run a EFlite Celectra charger on my batteries with a Astro Blinky balancer. The Astro blinky leds for each cell will light up for 3 seconds if that cell is at 3.2 volts or above. If not, you need to slowly trickle voltage into it and see if it gets above 3.2, BEFORE normal charging. If it won't come up, that battery is garbage. Same goes for overvoltage charging a LiPo. The Astro Blinky will safely discharge and balance overly charged cells. If you read some of Betapilot's posts, he only runs 5 minutes on his stock ESky 11.1 lipo battery. My advise is to check your voltages during flights to see how much flight time your batteries give you before hitting the 3.2v/cell limit. Most of this info is ignored or not known and thats why you hear people saying their battery only lasted 10-20 flights or starts to bubble.

RE: esc question
 

Thanks ezveedub. Then I wonder what's causing the motor to stutter and cut out. the brushed didn't do that. I went ahead and ordered a Dynam 30A esc and I'm gonna hope that clears up the problem. the lipo's are practically new, one is a 11.1v 3s 1000 mah 10c and the other is a 11.1v 3s 1250mah 12c. They can't both be damaged. But maybe they are. After I charge them, I check them with a digital voltmeter and they are both over 11.1v. So then a lipo rated at higher mah gives more flight time? thanks for not flaming me cause I think these are dumb questions I'm asking.

RE: esc question
 

Jet.......... a 3 cell lipo at full charge should read around 12.4 -12.6V...... Is there a possibility that you aren't fully charging your lipos? Each cell is capable of safely having 4.2V at full charge. Is your charger not fully charging your packs? What do they read at discharge? I have a couple of 1250mah 3S 11.1V lipos and they both at fully charged state read 12.45V consistantly.
There is no reason to flame anyone for asking a valid question, in this forum or in any venue. Your question is more than valid and deserves decent answers. ezveedub is right in that the ESC is working as it should. My guess is that you are not working with fully charged batterys and thats why you are not getting any flight time. What charger are you using? Hopefully mrasmm will chime in on this thread too, he has a deep knowledge of electronics and also understands the lipo chargers better than most.


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Of all the things I ever lost....................................... I miss my mind the most!

RE: esc question
 

One stupid mistake I made was using my 12v charger on my 1/8 starter box for input voltage. It has a gel pack 12 volt battery. It does charge my batteries, to a point. I forgot to check the battery voltage and started to charge my lipos. It was telling all my batteries were charged, but the heli wouldn't lift. After some testing, if found I ran my 12v battery down to 4.7 volts. The charger was telling me they were charged. Make sure you use a good 12 volt source. Most car batteries are 12.6 NEW. If they are good, they will have higher surface charges above this. If I charge from a car, I try to charge from a running car so I wil have above 13 volts of input for the charger that constant. Since I have the Thunder Power 2100 LiPo, I run a 2 amp charge rate.

RE: esc question
 

Thanks for the feedback folks. Ok. I checked the voltage on my 3s 1000mah 10c battery and the voltage reads 11.42 fully charged. I'm using the stock Esky charger EK2-0851 that came with the King 2. The other battery is a 1250mah 3s 12c and it is reading 11.46 fully charged. I'm charging it with a cheapie charger, a Mini-smart 2-3 cell lipo charger balancer. Do these voltages seem ok? I think now that maybe the Mini -smart charger is only good for 1000 mah lipo cause the model number say LPC-1000 so maybe I'm not getting a full charge on the 1250 ? Also I found out I didn't have my esc programmed right for 100% power at max throttle.

RE: esc question
 

I'll check my batteries later to see how much charge the EFlite Celectra with Astro blinky balancer is putting onto my LiPos. I'll check the ESky & Thunder power packs I have and give you the cell charge on each cell. Yours does sound charged. Some chargers have different cutoffs in their programming.

RE: esc question
 

Ezveedub, do you think it's better to have a charger balancer that has at least a 1 amp output to get the max charge? The ones I'm using only have 750 ma and 800ma outputs.

RE: esc question
 

OK, so far, I just charged the ESky 1000Mah 10c 3 cell LiPo. The total charged voltage is 12.56, cells are 4.191, 4.179. & 4.19. Thats charging with the Astro Blinky attached to the balance port and waiting for the leds to stop flashing (about 20 seconds) after charging shut off.

Thunder Power 2100 11.1 Volt 15c 3s LiPo has same results-12.56 charged voltage, cells=4.189, 4.181, & 4.19 volts.

RE: esc question
 

I honestly stand by my original answer........ Your batterys are not getting fully charged. After running any of my 3 cell lipos and putting them on the digi voltmeter i usually see a voltage of around 11 volts. Someone can explain it better than I can but usually when you run the lipo down to a certain point (say 10V) and then let it rest it will jump back up to the 11 to 11.5V reading. If you tried to use it again it would immediatly drop back down to the 10V or even closer to the 9V readings. Any way you can charge your batterys using a verified charger? LHS?? Buddy?


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Of all the things I ever lost....................................... I miss my mind the most!

RE: esc question
 

:DThanks for the input. It looks like I need a better quality charger. I'm convinced too. I saw an Align 2-3 lipo charger 1000ma output and it wil also charge two 2s at once which I use on my coaxial. It's under 60 bucks. I don't want to spend too much on a charger but I want one that will do the job. Thanks.