Over driving a motor

[Hvon11]

Has anybody tried over voltaging/powering a motor for just a few seconds?
I have a 70mm EDF in an F22 Raptor rated for a 4S battery. Motor specs below.
KV: 2800 rpm/v
Voltage: 14.8(4s)
No load Current: 2.8A
Max Current: 43A
Max Power: 730W
It’s a bit sluggish for the first 3 seconds of takeoff. To get a bit more launch acceleration, was wondering if I put a 5S battery in it, will it survive the initial 3 seconds and then I could back the throttle off. Thoughts?

 

[Tench745]

Will it survive? Yes, maybe, for a while.
That is probably as accurate an answer as any of us will be able to give. Some motors will way out-perform their specs (usually high-end models), and some motors are rated right at the cusp of what they can handle, so any pushing you do puts them over the edge. And sometimes you just get lucky, or unlucky with what any motor will tolerate. Which is yours? We don't know, and likely no one does. The best you can do is try it and see how long it works until it stops working anymore.

 

[LitterBug]

You "should" be OK for short bursts. I have used 3S motors on 6S with no damage. Just make sure you watch for excess heat. If you already have a hot motor, don't do it.

LB

 

[Hvon11]

Will it survive? Yes, maybe, for a while.
That is probably as accurate an answer as any of us will be able to give. Some motors will way out-perform their specs (usually high-end models), and some motors are rated right at the cusp of what they can handle, so any pushing you do puts them over the edge. And sometimes you just get lucky, or unlucky with what any motor will tolerate. Which is yours? We don't know, and likely no one does. The best you can do is try it and see how long it works until it stops working anymore.

Will it survive? Yes, maybe, for a while.
That is probably as accurate an answer as any of us will be able to give. Some motors will way out-perform their specs (usually high-end models), and some motors are rated right at the cusp of what they can handle, so any pushing you do puts them over the edge. And sometimes you just get lucky, or unlucky with what any motor will tolerate. Which is yours? We don't know, and likely no one does. The best you can do is try it and see how long it works until it stops working anymore.

Thanks. I will give a 5S a roll tomorrow and post results.

 

[Hvon11]

You "should" be OK for short bursts. I have used 3S motors on 6S with no damage. Just make sure you watch for excess heat. If you already have a hot motor, don't do it.

LB

Cool. I will try a 5S tommorow and post result. By the way, how does one become a Troll Spammer?

 

[Ketchup]

Imo a few seconds of sluggishness after takeoff isn’t really worth the extra weight and danger of a 5s (not really dangerous but you risk burning out the motor or ESC). If you take off from the ground, then you can use a longer takeoff roll, and if you hand launch then a harder toss could fix your issue. The way you worded your problem makes it sound like the plane flies fine otherwise, and if it gets in the air then I don’t see the need for all the extra stuff. Also you should consider that the 5s will add weight and depending on the size of the pack it may not fix your problem at all.

 

[LitterBug]

Imo a few seconds of sluggishness after takeoff isn’t really worth the extra weight and danger of a 5s (not really dangerous but you risk burning out the motor or ESC). If you take off from the ground, then you can use a longer takeoff roll, and if you hand launch then a harder toss could fix your issue. The way you worded your problem makes it sound like the plane flies fine otherwise, and if it gets in the air then I don’t see the need for all the extra stuff. Also you should consider that the 5s will add weight and depending on the size of the pack it may not fix your problem at all.

You are assuming that he is using the same mah rating when going to 5S... Just because he is going up to 5S does not necissarily indicate weight gain.

 

[Hvon11]

You are assuming that he is using the same mah rating when going to 5S... Just because he is going up to 5S does not necissarily indicate weight gain.

Yes, I am using a similar weight 5S battery with slightly less Watt hours. To add clarity, I hand launch as my field has long grass and no runway. It flies awesome once it gets good lift after around 3 seconds of struggle. I am 30% unsuccessful in getting up up and away. On the times that I can’t get the lift I do manage to slap the ground with no damage. Looking for a better ratio of launches to fly.

 

[Hvon11]

Imo a few seconds of sluggishness after takeoff isn’t really worth the extra weight and danger of a 5s (not really dangerous but you risk burning out the motor or ESC). If you take off from the ground, then you can use a longer takeoff roll, and if you hand launch then a harder toss could fix your issue. The way you worded your problem makes it sound like the plane flies fine otherwise, and if it gets in the air then I don’t see the need for all the extra stuff. Also you should consider that the 5s will add weight and depending on the size of the pack it may not fix your problem at all.

Yes, I am using a similar weight 5S battery with slightly less Watt hours. To add clarity, I hand launch as my field has long grass and no runway. It flies awesome once it gets good lift after around 3 seconds of struggle. I am 30% unsuccessful in getting up up and away. On the times that I can’t get the lift I do manage to slap the ground with no damage. Looking for a better ratio of launches to fly.

 

[Bricks]

First check to make sure your ESC can take 5s if not you may fry it as soon as you plug it in.

 

[Hvon11]

First check to make sure your ESC can take 5s if not you may fry it as soon as you plug it in.

It’s a 60amp ESC rated up to 6S so that should be ok. The motor is rated at 4S and that is what concerns me. Will give it a whirl tomorrow. Stay tuned.

 

[Bricks]

It’s a 60amp ESC rated up to 6S so that should be ok. The motor is rated at 4S and that is what concerns me. Will give it a whirl tomorrow. Stay tuned.

May want to go to a smaller prop and use a watt meter..

 

[Piotrsko]

I'll add (since I am a prime abuser) motor failures are a winding insulation / demagnetization issue. Aka I2RT in electrical terms. Sometimes the bearings fail. If it doesn't get too hot, should be ok, but everyone else is correct with their posts about the electronics.

BTw the Kostov in my Ford ranger is rated for 400 degrees on the comm for 2 minutes. More than that the comm makes fire extinguishers necessary. I have a comm temp sensor, do your motors?

 

[Hvon11]

I'll add (since I am a prime abuser) motor failures are a winding insulation / demagnetization issue. Aka I2RT in electrical terms. Sometimes the bearings fail. If it doesn't get too hot, should be ok, but everyone else is correct with their posts about the electronics.

BTw the Kostov in my Ford ranger is rated for 400 degrees on the comm for 2 minutes. More than that the comm makes fire extinguishers necessary. I have a comm temp sensor, do your motors?

I don’t have a temp sensor on this F22 but I do on the A10 and I appreciate it when it alrams.

 

[Hvon11]

So all went fine. The 5S did what I needed, which was provide for a better launch experience. Instead of fluttering about as lift is being developed, it took off and away at a steady climb for just under 3 seconds at which point I backed off the throttle to about 75%. I calculated about a 3 minute flight time based on actual 4 minutes with the 4S. I got right at 2 minutes 10 seconds before the ESC went into low power mode and was able to make an exceptionably beautiful landing. (I have yet to review the video). I assume the shorther flight time is due to not actualy being at 75% throttle and perhaps closer to 85%. Thanks for the support on this.

 

[Piotrsko]

Last I knew, there was temperature regulation on the power electronics in a inaccurate sloppy control system. Basically if it gets too hot, it shuts down but it isn't calibrated or very precise and cheapo motor controls are just that. Way back in the day, we had heat sinks but they were more expensive

 

[Hvon11]

Last I knew, there was temperature regulation on the power electronics in a inaccurate sloppy control system. Basically if it gets too hot, it shuts down but it isn't calibrated or very precise and cheapo motor controls are just that. Way back in the day, we had heat sinks but they were more expensive

You are right about the temperature regulation. It appears the ESC shut down on temperature as when I recharged the battery it was at 50% remaining capacity. Which supports my calculation for at least a 3 minute flight. The ESC is mounted on the belly of the jet and is exposed. I cut out the heat-shrink that covers the heatsink to better expel heat. Photo below. On 4S battery it never overheats. So I think the 5S gets things really cooking. I will try again with further reduced throttle to see if it happens again. Unfortunately it is raining here and may be a few days before I can.

get it out.

 

[Piotrsko]

Score a T-05 heatsink and see if that helps, borrow a rc car esc with fins........

 

[skymaster]

I think the esc should be inside the airduct with the edf. as the air goes through the front and out the back more air is passed over the esc than when it is outsiede, just have to make sure to secure it very well. that's how i have my X-29 setup.

 

[Hvon11]

I think the esc should be inside the airduct with the edf. as the air goes through the front and out the back more air is passed over the esc than when it is outsiede, just have to make sure to secure it very well. that's how i have my X-29 setup.

Good idea. I will look into seeing if I have the room.