The motors on my X-quad will be Eco II 1300kV and the ESC will be a Tekko 65/75 Amp. eCalc says that using a 6S battery will give a longer flight time at much reduced throttle setting, but at the cost of a higher temperature. It warns that “medium” cooling on the ESC will result in 88C, while “good” cooling is in the green at 69C. My question is: what would constitute good (or better) cooling? I’m still designing the frame, and planned on the FC/ESC stack to be rear of the hub and open on two sides (top and either bottom or rear). Would this be considered good cooling?
good bad cooling refers to the motors, not ESC I believe. As to stacks, you probably can run an open 30 mm stack at about 10…12 A x 4 indefinitively (my case, air temperature about 25 C). If this gives you hover current (at lowest battery Voltage), you are OK. 20 A x 4 usually has a thermal shutdown after 2 … 3 minutes.
Thanks for clearing that up. I wonder now how motors can have anything other than excellent cooling. There’s all that airflow from the props.
I don’t know what you entered in ecalc but if the warning was exact as you stated
then Ecalc is not refering to the motor temperatur but to the ESC temperature. Most commercial electronic has a maximum operational temperature upto 70°C, industrial electronic upto 85°C.
See also the remark on Hoybro webpage for " Tekko32 F4 Metal 4in1 65A ESC (AM32)"
Note:
Air flow for the ESC is very important if you want to run this 4in1 in high current.
My design will have the FC/ESC stack open to the top, bottom, and rear. I wonder if that would provide sufficient airflow. Perhaps I should start with a 4S battery. However, using 6S would reduce linear throttle from 48% to 37% at hover, and increase hover time from 17.1 to 17.7 minutes with a 5000 mAh battery.
If you want use to compare the batteries you also give all details:
4S capacity (mAh) is missing. And weight for both batteries
You are right, should have included more info. Here are two screenshots of eCalc, with only the type of battery changed, same total mAh and weight. The Tekko ESC isn’t in the database, so I’m using custom numbers.
Anything less than “excellent” cooling pushes the 6S into the red.
You did not undersatnd one thing:. there is the temperature at max power, and there is temperature at hover power. For hover, if the weight is the same, the motor temperature will be the same with 4S and 6S. Hoever, if you push the throttle to maximum, you will get much more power to the motor with 6S than with 4S (about the double). And so the temperature would alo be much higher with 6S. You have to look at the temperaature for motor at hover. Ecal is not very precise at estimating tempertures though… Weight of the battery will not be the same for the same mAh at 4S and 6S.
Yes, I still have a lot to learn about drone design. I will design the FC/ESC mount to be as open as possible while still providing some protection from hard landings, I still wonder what excellent, good, and medium mean in terms of frame design.
Then read the Help Docs
eCalc
I have. This is what it says about cooling the ESC:
Remember the ESC is able handle the max. rated current only under these circumstances:
- with efficient cooling airflow
- at full throttle (no pulse width modulation active)
We suggest to plan for additional headroom of - 20% for inefficient cooling airflow
- 40% for convective cooling
- 20% if used in partial load
My question has to do with what physically constitutes efficient airflow in a well-designed Quad-X frame. I will try the open frame first, probably with a 4S battery, then maybe try adding an air scoop to the bottom of the frame. That would only make a difference in forward flight, of course, and might otherwise prove a hamper to cooling. Thanks to everyone for the help.
Also during hover the drone needs more power as the battery weight increases by 50% based on the 4S battery pack. The effect is seen on the charts as with 50% more battery power the flight time only increases less than a minute. The increase of weight is also shown on the charts.
Same weight of battery was referred to a single cell
Yes, I see that. I’ve decided on using a 4S 3000mAh battery by Lumenier.