FG NOOB, AND I NEED HELP!!! LIPO HELP!!!

[aryajet]

OK heres the setup.....

1. 25C/50C 3700 EVO 6S
2. 77 SPIN ESC
3. AXI 4120/18
4. PROPS TRIED - 15x8, 16x8 APC & XOAR

My question is why is my battery getting so hot with mainly the 16x8 in flight and static tests showed heat developing very quickly. The battery and the wires on the deans plug from esc to batt on the esc side are hot!! Too hot to be normal. Now here the number my watt meter shows at wot...

1 - APC 15x8 60A 1200W 8.5lbs static thrust (little to no heat)
2 - APC 16x8 71A 1600W 9.5lbs static thrust (most heat developed the quickest)

3 - XOAR 15x8 55A 1100W 9lbs static thrust (little to no heat)
4 - XOAR 16x8 66A 1500W 10lbs static thrust (heated up enough to alert me)

This setup is on a 50 KATANA. Now why would my battery heat up so fast with the larger prop. The amp rating are within the limits of the esc and the battery??? Is there something Im doing wrong??

I have all of it set up ona deans arming switch. I was thinking maybe resistance somewhere? Maybe the motor cant handle it? But if the motor cant handle it why would the battery heat up?

Im obviously very confused HELP!! SOS!!!

PS Im loving the FG community bc its the only RC forum with a sense of humor!!

AMIR

[aryajet]

pic

[Uncle Brett]

Could be a couple of things. First of all, if you've only checked the battery temp static, you don't have sufficiet airflow over the battery and ESC to cool them down.
I think the main reason though, is resistance, and that could be comming from a few different places. The Deans plug is not really designed to handle that much power so that could contribute. I think something like Power Poles or the bigger 6mm connectors that Neu Motors sells would help. There's also the possibility of a bad solder connection either on the plug comming off of the ESC or on the battery.

[aryajet]

Thank you so very kindly for your help. And I appreciate that were on the same page about my problem makes me think I know what Im doing. Anyway seems I have some investigating to do.

Another question...

The AXI 4120 is rated up to 55A. If you notice my numbers, heat began to develop once I began to pass the 55A range. Now I did fly one time with the 16x8APC and when I landed the battery was extremely hot. If the motor rating is 55A, then why would AXI recommend the 77A esc? I bought them together from theyre recommendation. My question is what happens when you exceed Amp ratings for the motor. Would you see symptoms like I have? My battery can deliver 90A cont, and the ESC 77A but if the motor can only handle 55A maybe thats where the issue could be? No?

Thanks again so very kindly for your help...

Amir
__________________

[scalefreak]

	Quote: Originally Posted by aryajet
	Thank you so very kindly for your help. And I appreciate that were on the same page about my problem makes me think I know what Im doing. Anyway seems I have some investigating to do. Another question... The AXI 4120 is rated up to 55A. If you notice my numbers, heat began to develop once I began to pass the 55A range. Now I did fly one time with the 16x8APC and when I landed the battery was extremely hot. If the motor rating is 55A, then why would AXI recommend the 77A esc? I bought them together from theyre recommendation. My question is what happens when you exceed Amp ratings for the motor. Would you see symptoms like I have? My battery can deliver 90A cont, and the ESC 77A but if the motor can only handle 55A maybe thats where the issue could be? No? Thanks again so very kindly for your help... Amir __________________

Your largest problem is definitely your prop size. Your loading the motor up pretty good. The battery is getting. The AXi's can handle more than they are rated for. If you are pulling 71 amps, it will likely drop back to 65 or less once you are airborne. Electric setups will unload in the air, just like a glow or gas engine. You can drop 5-8% off of your static numbers for what would be accurate for in flight. Make sure your prop is well balanced, as an imbalanced prop will only increase your current draw. Adequate cooling, which you probably already have, is a huge help. Static testing electric setups in the ground for longer than a few seconds at a time is the most unhealthy thing there is for your components. Take a short flight, 2-3 minutes, check your temps. If an outrunner gets hot, thats bad. They typically feel cooler, because the magnets and bell housing insulate the heat coming from the windings on the stator. When an inrunner gets hot, it's a good thing (to a degree), because the tight wire windings and case help to dissipate the heat, acting like a heatsink.

[aryajet]

I think Im gonna try the 15x8, and 16x8 XOAR's this weekend and then like you said fly for a said 3min, bring her down and temp the battery. Then I will go from there....

Thanks for your clear concise responses, all of you are a real blessing, I dont know what I would do if I had to deal with this problem alone and confused.....

[Uncle Brett]

I think scalefreak is right about the prop size. I didn't realize the Axi was only rated for 55 amps. As your numbers indicate, the 15" props @1100-1200 watts should be more than enough for a plane under 7 lbs. Pushing that motor to 70 amps is going to heat everything up. Hopefully you haven't overheated the mags to the point where they now will go to terminal degragation.

[aryajet]

I hope I havent damaged anything, I fly hard!!! The one flight I did get in, I was inverted at about 3/4 throttle I began a 45 upline, I threw the sticks full down inside snap and as it began to tumble the canopy flew off and split in half midair!!! The picture shows the replacment canopy.

Anyhow for my style of piloting I think if I use the 15x8 XOAR everything should be alright. I think I was trying to maximize everything too much. But man with 1600W this thing was more than unlimited vert, it would do like 70-80 mph passes downwind!! Maybe more.....

Guys I really appreciate your assitance, thanks again. I will post my result of my flight test this weekend....

Amir

[scalefreak]

	Quote: Originally Posted by heydick
	I think scalefreak is right about the prop size. I didn't realize the Axi was only rated for 55 amps. As your numbers indicate, the 15" props @1100-1200 watts should be more than enough for a plane under 7 lbs. Pushing that motor to 70 amps is going to heat everything up. Hopefully you haven't overheated the mags to the point where they now will go to terminal degragation.

It gets spicy when the magnets decide to do their own thing....can you say coffee grinder?

[scalefreak]

	Quote: Originally Posted by aryajet
	I hope I havent damaged anything, I fly hard!!! The one flight I did get in, I was inverted at about 3/4 throttle I began a 45 upline, I threw the sticks full down inside snap and as it began to tumble the canopy flew off and split in half midair!!! The picture shows the replacment canopy. Anyhow for my style of piloting I think if I use the 15x8 XOAR everything should be alright. I think I was trying to maximize everything too much. But man with 1600W this thing was more than unlimited vert, it would do like 70-80 mph passes downwind!! Maybe more..... Guys I really appreciate your assitance, thanks again. I will post my result of my flight test this weekend.... Amir

You bet

If you want silly power on a 5--60 size airframe and HAVE to use an AXi... the 4130/16 on 6s 3300-3700 with a 16x10 APCe is STUUUUUPID! I have version of the old school Super Hots that build up every once in a while that will 3D good and it is phenomenal power.....otherwise a Hang-It R/C x4130/06 on the same pack and 16x10 is equally ridiculous (1880 watts - 7 lb airframe - 270 watts per pound!).