What is "Reasonable"

[Leejax01]

Trying to make a long story short, I bought a P4 from Best Buy and it had some sensor calibration issues and a GPS warning when in forward flight even after a successful calibration, so it was returned for unit 2. This one flies ok, but one of the motors feels a little stiff compared to the others. Doesn't get hot, just doesn't sound or spin like the others. It isn't notchy or gritty, just doesn't feel right. I'm contemplating taking it back for a 3rd one, but is that being unreasonable? I've had one before and all the motors were silky smooth. What's an acceptable margin here in what to reasonably expect? The motor could potentially fail in the future sure, but who's to say? I really don't want to take it back and get something potentially worse and then what?

 

[Knoxville drone guy]

Just return it. It will go back to dji and maybe they will work harder on quality control. It's a lot of money you should be happy with your purchase


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[flpholt]

I agree

 

[NorthcountySD]

If you're not 100% happy bring it back till you are. The policy allows this and although a but uncomfortable, how will you feel it it has an issue that crashes it in a month or two? For the price you are paying for a quality product.

 

[QuadBart]

Maybe check out #3 before you accept it and leave. Meaning check motor movement and inspect it. Sure its not going to show you any issues that may reveal themselves once started and flying, but you might catch something and save you another trip...

 

[alokbhargava]

Good that you are able to identify issues which others don't see them.

You can ignore cosmetic issues but can not accept products with defective parts that make a phantom fly to its designed specs.


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[RémyHeli]

Pre-Flight check-list # 2

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[joet]

I concur. Return it and get another. Repeat until you are happy with it.

 

[Leejax01]

Thanks guys. I'll most likely return it, but admittingly I'm a little gun shy seeing the other P4 issues out there. This one doesn't have tilted gimbal issues or anything else not noticeable via a quick inspection. Actually flew nice with great range at 9.3k feet in an area I was only getting 7k max with my very first P4 and my other 2 P3Ps.

 

[Leejax01]

Even the fit seems nice! That one motor!

 

[Kamloops]

If you are getting great range and no gimbal issues, I would keep it. A replacement motor is around $22.00 and that is a bargain if everything else is working great.

Should you have to do this? NO.
Is is worth it for a bird with no gimbal issues and great range (mine had great range and sometimes wonder what everyone is grumbling about lol)? YES!

 

[Leejax01]

Thanks for the video RémiHeli and according to it, the motors sound fine when powered up and idling/ running. Kamloops I'm feeling how you're feeling as the 2nd one didn't have the range this one has and had several in flight warnings. Both issues I couldn't tell from an inspection. Question is does everyone's motors all spin/ sound the same by hand? Maybe that's not a good judge of motor efficiency.

 

[RémyHeli]

All 4 motors should be identical by hand. Maybe bearings related. Not sure if short video can help here so maybe you can detail what you feel exactly.

We use lot of bearings in helis and can happen to have slight differences when checking them by hand. Inner race tolerence, balls, packed grease difference or eventually hardened grease if long storage.

But rotation should be smooth and with little difference. We're talking about new bearings and they will self-adjust during usage.

From Boca Bearings website:
****
Most bearings are packed in thick, viscous grease or with a light weight oil. As a result the bearing generally will not free spin to the touch. Over time as the lube thins out, and warms up during each use, the bearing will become much freer. So all you need to do is to use the bearing normally and it will break in naturally. The more you use the bearing the more broken in it becomes until eventually it is so broken in that it is time to replace it.
****


I would let the craft spinning for one hour with props and re check to see if any difference.

But agree it's a flying object and lot of money so if you are not confident return it. You should be comfortable flying it.




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[GMack]

I did a comparison on my P4 with a tachometer (Harbor Freight for ~$30 with a 20% off weekly coupon.). All four motors at idle on a level surface were about 3,100 RPM +/-50 RPM. All feel equally warm and make a slight whir noise if I quickly flip the props by hand. I guess that is good.

Fwiw, this was the third I got out of Best Buy as they others had manufacturing defects and never hit the air. They are really good on the exchange process and the girl said they've gotten a few back. DJI QC is suspect at times.

 

[Leejax01]

Ok guys, I did return it and #3 motors seems equal! I did range test in an area I commonly get 9k feet no issues and was only able to get 8.5k with issues. Oh well!