|Sep 30, 2012, 06:35 AM|
Joined Aug 2011
Tiger motors - Buyers be aware
I'd like to share with you the experience I had with http://www.rctigermotor.com/
I build and fly camera mounted quadcopters as a hobby.
I was looking for the ultimate motor for my new 2.5Kg mahcine.
As you might know - for quadrotors, it's recommended to use a low Kv , high torque , direct drive brushless motors.
Tiger Motors seemed to show some very optimistic numbers on their website:
I thought they were a little OVER OPTIMISTIC.
Nontheless, I decided to give them a try and bought the MT3506 together 2 other motors (as candidates to for my new machine):
When I recieved the 3 motors I tested the MT3506 first (the motor in the above link).
I connected it to an APC12*3.8 prop, a 3 cell 5000mAh LiPo battery and drove it with the Tiger motors ESC30A.
The system has been mounted on a custom test stand on top of a digital weight scale.
static thrust has been measured through the Amperage range as I increased the throttle on my radio.
At 5.7A the system produced 520 grams of thrust.
I referred to the table at the above link - It claims 620 grams of thrust at 5A of current conssumptiion with the same setting as I tested in my lab.
That's 20% more thrust than I got at 20% less power conssumption!
Adding up to a 40% SHAMEFULL LIE!!!
I proceed to testing 2 of the others motors and compared them to the data on the site - THE RESULTS WHERE EVEN WORSE!!!
The difference between the data on the website and my test results where off by as much as 45%.
I sent 2 E-mails to Tiger Motors showing them my data and asking for explanations! It has been 2 weeks ago and I haven't heard from them yet.
Buyers be aware of the fraudulent performance claims made by Tiger Motors on their website!
|Sep 30, 2012, 09:33 AM|
I have bench tested hundreds of motors and, sadly, only rarely do any of them live up to the advertizing hype! In most cases I doubt that the manufacturers and distributors actually critically test their products to generate reliable data.
Watch this space...http://www.rcgroups.com/forums/showthread.php?t=1733906... we'll get a truly scientific appraisal of at least this one T-motor from Louis.
|Sep 30, 2012, 10:24 AM|
USA, ME, Ellsworth
Joined May 2008
What zeroback says! We have to determine most or all the numbers for ourselves to get realistic or honest ones, the advertised specs are just too variable and unreliable.
And I think your expectations may have been set a little to high as far as how closely the numbers will match up from one testing setup/testing person,/testing location to another. And your criticism is probably a little too harsh.
The prop performance (i.e., thrust) for a given propeller will not vary too much from one motor to another as long as you are using similar motors and input power.
One of the most reliable sources we have for honest test data is flybrushless.com. If you choose one of the props that Tiger Motors tested, the APC SF 11 x 4.7, and look it up in the prop database there you can see a thrust to RPM curve for the prop:
If you look at the Tiger Motor MT35-06_MT (a 70g 650 Kv motor) test data for that prop on 3S you see:
APC 11x4.7 - 11.1V - 7.9A - 88W - 780g - 27.5oz. - 5280 RPM
And if you go to the flybrushless.com test data you can choose a similar motor motor from the list below the graph. I chose the Pulso - X 2212L/34 (62g, 670 Kv) motor and found these number for 3S testing:
APC 11x4.7 - 10.9V - 8.2A - 89W - 683g - 23.1oz. - 5190 RPM
The two motors vary in weight by 8 grams. There is a difference of 97 grams (14%) in thrust and one Watt in the input power.
The variations from one test setup to another can account for considerable variation in any or all of the numbers. In particular, the thrust is the number that can vary most widely. That is because of the various mechanical setups and measuring methods that are used from one test setup to another.
Those Tiger motors look to me to be typical quality Chinese made motors. The do provide pretty well detailed specifications and those seem to be reasonably honestly stated.
The MT3506-MT is a 70 gram motor and they rate it for a Max Continuous Power(W)180S of 200 watts. That is an input power of 2.9 Watts per gram and that is a very typical number for average quality Chinese made motors.
If I question anything about Tiger Motors it is their prices. They have a suggested retail price of US$64.9 ($64.90 assumed). If you compare it to some similar motors you can buy as many as three motors for the same money. Here is one example:
I don't have any testing data for the RCTimer motor and don't have either your motor or the RCTimer one. But I can't help but think that the Tiger Motors line is a little bit over priced.
We have our 3 Watts per gram rule of thumb for estimating power, maybe we need to have grams of motor per US$ rule of thumb too for evaluating the price structures?
Tiger Motors = $1.00 per gram for the 70 gram MT3506-MT
RCTimer = $0.27 per gram for the 73 gram MT4215(3507)
|Oct 01, 2012, 12:51 PM|
Joined Jun 2012
They have some IMPOSSIBLE numbers on their data sheet for the MT3506. I also tried to get some explanation from them. My conclusion is that they are BOLD FACED LIARS. Each time I pointed out a flaw in their method, they simply responded, "no our method is accurate you do not have to worry about the values" I got a pic of their test setup and found out they're using the current reading from the FRONT OF THE POWER SUPPLY! Anyone that's worked in a lab knows this is a big no-no. These are notoriously inaccurate. Furthermore, they use a cheap Mastech power supply. I have one of the same models of my own, and sometimes the current doesn't even read. For example, I'll be puttling 6 A and it'll read 0.5. It's that bad. So they're getting these numbers b/c the current reading is way low, making the motor look amazing. I asked them repeatedly to measure voltage and current with proper instruments, but they refuse, and continue deceiving their customers.
It should be said that these motors are good for their price, but their performance is NOT above average as they are advertised.
|Oct 01, 2012, 01:32 PM|
They do post some more complete data tables for that same motor (different props from those shown by Bruce's link, http://www.rcgroups.com/forums/showthread.php?t=1666391 this time with RPM) : http://www.rctigermotor.com/show.php?contentid=142
Odd that in Bruce's link the Rm is different (155 milliohms) from the OP's link above (143 milliohms)!
|Oct 01, 2012, 03:30 PM|
Joined Aug 2011
Even though their motors are "good for their price" I wouldn't recommend them to anyone.
There're dishonest people that don't diserve honest customers!
|Oct 02, 2012, 06:51 PM|
I've always had the impression that T-Motor is a company that got some good contacts with some reputable suppliers, and from there abused the growing high-$$ multicopter market full of people with lots of money but not much experience... The only T-Motor users I've seen have only used them once before switching back to their turnigies.
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