Hi Josh, There is a thread somewhere here that quotes Holger saying that his ESCs don't play nice with high pole count motors. I think it may have been Dave King who was having trouble with his?
I am let to believe they might have a bit too much oomph for that board..( depending on weight and props used...) current: up to 60A peak (per BL-Unit) and 240A (all together) with appropriate cooling That equals 30A per BL continuous In the KDE motor spreadsheet you can see that if you use props bigger than 15" the motor pulls 15-30 A in the 50-75% throttle range but up to 40-50A at 100% throttle. So for normal use it seems to be fine, well within specs, but a full throttle manouver ( emergency pull out or something) could create spikes up to 400A which is well over the boards specs of 240A all up. Not sure if I would be happy to fly a big expensive rig knowing that I run the risk of blowing my power Distribution / BL controllers if I have to give full throttle for some reason... And than there is the above mentioned 'problem' that there are still some issues with high pole count/ high current engines. For smaller engines that board is awesome and works quite reliable here. Just my two cents...
Josh I mentioned this in another thread as well I have not had any issues with major failure with my MK 2XL quadro power board. I did fry a board out trying to do the updates but its been replaced since then. The first generation boards needed a lot of little fixes and updates but I think its really coming around now. I sent Holger a few motors to test including the 4014 and he made some changes based on his testing from that. Ozkan (another user on this forum) recently burned up a BL with this combo (not sure on the prop size he was using) but it was at a lower paylaod than what I fly with. He however did not log any data so we really don't know what happened with his failure. The one thing I really like about Holger and MK is that if the issues were with their electronics he won't side step it and blame something else. I am very impressed with their fast and super helpful customer service.
Holgers Response to my question of if the 5215s would work: "We recomment to select a motor pulls at 100% throttle did max. 40A Reasons: first The current peaks can be much higher When The motor changes the setpoint (For Example from 50% to 100%) the second The current summation of eight motors would be really high. You must multiply the maximum current by eight. We designed and tested the 2XL Cool for a peak current of 250-300A in summation -> did is silent more than 8,5kW at 7S Regards, Holger" I also have been talking with Andreas about the Herk III board. Here is his response: "Hi Josh, the rating of Herkules is done very honest and more on the safe side. When we specify 30A continous, than the ESC can be driven with 30A continous without limitation. And this is valid for the part load, remember this! At full-load (100% duty cycle) the ESC can drive even more. No one of the known ESCs on the market is specified at part load, which is the use case in all multicopters. So in fact. Herkules can driver 30A continous (with good cooling) and 60A peak for a few seconds. For multicopter, the average current is the main key. You can calculate this pretty easy: Assuming: - Kopter Total AUW 15kg - Motor / Prop combination efficiency: ca. 8g/Watt => Total average Power: 1875Watt - with 6S Battery voltage (22V average) => Total Battery current: 85Ampere with Octocopter => 10.7A avarage current per motor! So a 15kg kopter will need at hovering around 11A per motor and peak 20A this is the fact. Mit freundlichen Gruessen, Kind Regards, Andreas Baier"
Well, I'm one of the guys who had problems recent weeks. I was flying with KDE 4014XF with 18" props when two of my BL burned. I couldn't post any logs since SD card was nowhere to be found at the crash area. I sent back the board back to Germany with a motor and prop combo. Holger is very responsive at this situations, so I truly believe that they will solve this issue. It is obvious that the boards has some problems, weather it's hardware of software based and I'm not the only one who had this burned mosfet issue. For Herkules III, Kopterworx has been using this board on their heavy lift copters for a long time. It's also a reliable choice. I will report my findings on 5215Xf-435Kv with Herkules III and DoubleQuadroXL once I have my motors here.
Hello Dave, The board is still in Germany and I have yet to get any updates from them. 5215XF-435KV motors arrived to me, I will also send them one 5215 motors to test with BL controllers. Once I get motor mounts, I'll also test the current draw on the bench.
Ozkan I would be very careful using those motors. The 435 KV motors appear to be draw too much current that the MK power board can handle. It's definitely too much using 17 and 18 inch props and its right on the borderline with 39 amps at full throttle using 16 inch props. IF you use a 16 inch prop less than 100 grams of thrust increase over the 4014's with 18 inch props. You could possibly run the 5215XF-330's. The specs just released appear to be 33.8 amps at full throttle with 16's props. At hover its putting out 2210 grams. See my write up on the Tiger motor tests I just did if you haven't seen it. http://forum.freeflysystems.com/ind...4120-heavy-lifter-motor-testing-results.5152/
I bench tested 5215-435KV with 16x5.4" and 18x6.1" Tiger carbon props. The current draw was very similar to KDE's spec. http://kdedirect.com/KDE5215XF435.html It runs scary powerful with 18" props and I could only go up %85 throttle. The Bl Controller reached 85C degrees within one minute. It was occupied with heatsinks, which helps a lot. I couldn't touch the heatsinks after 2 minutes. It can be different when the copter is on the air though. I changed the throttle pretty fast to see if the BL Ctrl will fail or not. It didn't burn but when changing the throttle pretty fast, red light appeared for a few miliseconds on the BL Ctrl. I think that's an indication of overcurrent protection. With 16" props, the max current draw was 37 amps.
Bench testing one motor is fine to see what the individual motor specs butr its not the same with the MK Quadro double XL board if you are trying to test the board to see if it will live because you have to remember that the MK boards are limited by the total power or specifically the total amount of current it is producing. I think its rated to 320 amps but realistically its probably more like 280 to 300 for reliable safety margins. If you are seeing 8 motors drawing 40 amps or more it wont' be long before that board is toast. Also as Andy found out full throttle is reached at a point less than full up. This means that you are applying full throttle at position on the stick a lot closer to neutral than you think.
That's one of the reasons I'm sticking with single BL Ctrl's right now. I have a 400A rated PDB to handle the current. I'm thinking to set up a big quad to fly with a dummy payload to see BL Ctrl's performance and heat. I agree that 18" and 5215-435KV is dangerous for BL Ctrl 3.0
I will post pictures tomorrow. To connect I2C lines, I use this board https://www.mikrocontroller.com/ind...id=826&zenid=7e6d485f902df0432765ebf3b490a5b4 Single BL Ctrl's come with a pre soldered 3-pin I2C connector. So, I use 8 of this 3-pin cable to this PDB and then classic 5-pin molex to the Flight Controller: https://www.mikrocontroller.com/ind...id=764&zenid=7e6d485f902df0432765ebf3b490a5b4 The setup is almost like this: I connect the power lines to another PDB to handle the current. The setup is not clean as I had with MK Distro board but I dont care as long as it works
I did same test with Herkules III. On the bench, I put 18" prop over KDE XF5215-435 and observe the temp of the ESC. What I can say is, Herkules III just stayed cool, not even a noticable increase in the component temp. I will plug 8 of XF5215-435KV to Herkules III and observe the temps. IMO, Herkules III is more durable and reliable againts high currents.