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Old Oct 14, 2012, 12:58 AM
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Originally Posted by IndyMatt View Post
I am assuming that was on 3S that you burnt the external ESC? I want to get some 3S batteries but I don't know how to make 3S batteries with the bare hyperion cells and the thunder powers are expensive.
Nope---On 2S...

I'm VERY serious---These NanoTechs deliver about 400 more RPM over my 240mAh 25C Hyperions...The extra poop didn't do the ESC any good...

Bare Hyperions are easy to solder with a good solder station...Forget about getting good joints with a Harbor Freight type soldering iron...I have assembled Hyperion 3S packs with a balance connector...Good soldering joints are a must!!!

Kevin
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Old Oct 14, 2012, 01:03 AM
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United States, TN, Jackson
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Originally Posted by flyrtim View Post
Nanotech 2s 35c 260 vs 300

anyone have both to give us comparison?

I have the 260 and I think my hyperion 240 are more powerful but
I read an earlier post stating that the 300's are amazing.
I put a tach to my Hyperion 25C 240's vs the Nanotech 35C 300's...I'm getting 400 more RPM from the NanoTechs over the Hyperion 240's...To rule out weak packs I tested 1/2 dozen Hyperion packs (I have a dozen) and all put out around the same power/rpm...

Kevin
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Old Oct 14, 2012, 12:40 PM
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I need to get me something to measure my rpms when I get my Nano 300s and 350s
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Old Oct 14, 2012, 12:49 PM
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United States, CA, Sebastopol
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Originally Posted by brushless55 View Post
I need to get me something to measure my rpms when I get my Nano 300s and 350s
I picked up a Globee tach on the forum for $10. I don't even know how it was worth it for the seller to box it up and ship it for that! So you can find them really cheap.
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Old Oct 14, 2012, 12:54 PM
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Originally Posted by Kevin Greene View Post
Nope---On 2S...

I'm VERY serious---These NanoTechs deliver about 400 more RPM over my 240mAh 25C Hyperions...The extra poop didn't do the ESC any good...
I don't get this...

A you can't force Amps around like you can Volts, they are taken as needed.
The extra 400rpm is an indication of a higher Voltage being used, that's what Kv is, right?

So if more Amps are available can this help to hold up the loaded Voltage


Tony
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Old Oct 14, 2012, 12:57 PM
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Originally Posted by brushless55 View Post
I need to get me something to measure my rpms when I get my Nano 300s and 350s
Pick up an optical tach, as that's the most accurate, repeatable means of measuring RPM on our planes. Be sure to do your RPM measurements under natural light only. House lighting and other non-continuous light sources will register on the tach & corrupt the readings. If the tach reads anything but zero when pointed at the light source, the RPM readings will be meaningless.

Also - some time ago, a number of us who do static RPM testing on UMs had settled on RPM @ 30 seconds into the run as a standard of comparison. To make it easy to compare results, I suggest that we continue to do so.

Joel
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Old Oct 14, 2012, 01:00 PM
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Originally Posted by SilentPilot View Post
I don't get this...

A you can't force Amps around like you can Volts, they are taken as needed.
The extra 400rpm is an indication of a higher Voltage being used, that's what Kv is, right?

So if more Amps are available can this help to hold up the loaded Voltage


Tony
The more amps a pack can deliver under load the more volts it will sustain

KV x Volts = rpm
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Old Oct 14, 2012, 01:10 PM
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Originally Posted by turboparker View Post
Pick up an optical tach, as that's the most accurate, repeatable means of measuring RPM on our planes. Be sure to do your RPM measurements under natural light only. House lighting and other non-continuous light sources will register on the tach & corrupt the readings. If the tach reads anything but zero when pointed at the light source, the RPM readings will be meaningless.

Also - some time ago, a number of us who do static RPM testing on UMs had settled on RPM @ 30 seconds into the run as a standard of comparison. To make it easy to compare results, I suggest that we continue to do so.

Joel
Thank you!
If you have a link to one please post it and I'll buy one today..
And yes I will follow the 30 second timing.
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Old Oct 14, 2012, 01:16 PM
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Originally Posted by SilentPilot View Post
I don't get this...

A you can't force Amps around like you can Volts, they are taken as needed.
The extra 400rpm is an indication of a higher Voltage being used, that's what Kv is, right?

So if more Amps are available can this help to hold up the loaded Voltage


Tony
Tony,

It's the difference in internal resistance between the higher & lower-C cells. Cells with higher true C-ratings have a lower internal resistance than lower-C packs of the same capacity. Cells with higher capacity also have a lower internal resistance than lower-capacity packs of the same C-rating. A cell with a lower internal resistance will maintain a higher voltage under load, as there is less voltage-drop within the cell. The difference usually becomes quite significant at higher currents in terms of 'C'. Also - internal resistance usually decreases as the cells break-in, and it goes up as they age (that's why they eventually get 'tired').

EDIT: I see that BL beat me to it. I type slow!

Joel
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Old Oct 14, 2012, 01:16 PM
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Originally Posted by turboparker View Post
Pick up an optical tach, as that's the most accurate, repeatable means of measuring RPM on our planes. Be sure to do your RPM measurements under natural light only. House lighting and other non-continuous light sources will register on the tach & corrupt the readings. If the tach reads anything but zero when pointed at the light source, the RPM readings will be meaningless.

Also - some time ago, a number of us who do static RPM testing on UMs had settled on RPM @ 30 seconds into the run as a standard of comparison. To make it easy to compare results, I suggest that we continue to do so.

Joel
I just ordered one of these: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXPT32 Hopefully will have it Monday

A few of the 'long-timers' gave it a recommendation, and I spent a long time researching laser vs optical and wanted to keep it under $100. I was hoping to be able to use use my Fenix LD20 on max for a reading, but sunlight shouldn't be a problem. Incandescent light will hose the reading, but would a strong LED work for this?

I've been planning on taking measurements @ 30 secs in as you said, having read a few hours worth of older RCG posts on that, as well. I have a few Hyp 180s seem to be running my SX motors at an audibly lower pitch than others, and wanted to confirm with empirical data.
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Old Oct 14, 2012, 03:38 PM
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BL,

You're welcome! There are many optical tachs out there that will work just fine. The biggest differences between the various tachs are the range from the prop at which they can be used, RPM measurement range, display resolution, and type of battery. The better tachs typically use focused optics, which allow the tach to be held a foot or more from the prop. Some can measure 100k RPM, while others cannot. Some have 10 RPM resolution, while others have 50 or 100 RPM resolution. Some are limited in digits & require the user to multiply by 10 to get the answer. Others read out the actual number. Some tachs use AAA cells, others use watch/calculator cells, and yet others use 9V batteries. Check your LHS or any of the online shops such as Horizon or Tower. Mine's a Hangar 9. It's a long-range, CR2032-powered unit with 10 RPM resolution, but it lacks the last digit, so the user has to multiply the reading by 10. The one that JayDoc ordered would also be a great choice. It's a long-range, AAA-powered unit with a direct readout. I'm not sure about the resolution, as it is not listed on the manufacturer's website. 10 RPM would be best for this app, but 50 RPM would be good enough.

JayDoc,

That tach is a good choice.

Regarding the light source - if your LED flashlight is light-engine-based, the output may be pulse-width-modulated, which will corrupt the readings. An easy way to check is to point the tach directly at the light-source at close range & observe the reading. If it remains at zero, your light source should be fine (as is the case with sunlight & all direct DC-powered, non-dimmable incandescent lamps). If not, you'll need to use a different light source. For instance, my Browning Catalyst 175 Lumen 6-volt LED flashlight reads 3690 RPM, but my 3W Luxeon LED 2-cell MagLight conversion reads zero.

For those who may not be aware - to check the calibration of any optical tach, simply point it at a 60 Hz incandescent lamp. It should read 3600 RPM in 2-blade & 2400 RPM in 3-blade. If you live where 50 Hz is the norm, then it should read 3000 RPM in two-blade & 2000 RPM in three-blade. There are usually cal trimmers inside for each blade setting.

Joel
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Last edited by turboparker; Oct 14, 2012 at 08:53 PM. Reason: Typos
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Old Oct 14, 2012, 04:57 PM
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The Hangar 9 was actually my other candidate and came highly recommended as well, but I essentially flipped a coin and ended up with the one that could use my Eneloops. I know that through normal use, either set of batteries would last a ridiculously long time - but it was more mental, really.

That is a really nifty tip on the calibration via 60Hz bulb, and I will make sure to try my array of various flashlights to (hopefully) find one without a reading of its own. You are absolutely right - all of my Fenix lights are PWM controlled so I'll need to experiment with the others.

Thanks again - you always seem to be a wealth of valuable information, and it is much appreciated.


EDIT: My little Fenix LD01 appears to be CC rather than PWM - might have a winner. Will find out Monday, and let you know the tach resolution, as well.
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Old Oct 14, 2012, 05:00 PM
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Tacoma, WA. USA
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My new bird is supposed to be here Tuesday. To feed my addiction while I have been waiting, I got motivated to run the wattmeter on my Beast to see the difference between the NT 260's vs the Mini 210's. I'll have to borrow someone's stock pack so I can get those numbers posted.

Stock motor (2500kv)
Stock prop (5x2.75)

Miniaviation 210mah 2s 25c:
Volts - 7.17
Amps - 2.66
Watts - 19.9

Turnigy 260mah 2s 35-70c:
Volts - 7.67
Amps - 2.76
Watts - 22.1

A 10% increase in power, that's going to be noticeable. That is only the first charge on the Turnigys, I expect the numbers to get better after break-in. Here's a buddy code for anyone interested.
http://www.hobbyking.com/buddy.asp?c...E-B7BB9022B3DA
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Old Oct 14, 2012, 05:10 PM
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is there one I can use on 4 blade props?
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Old Oct 14, 2012, 05:22 PM
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Originally Posted by brushless55 View Post
is there one I can use on 4 blade props?
Some have a dedicated 4-blade setting, while others don't. Mine Hangar 9 tach has it. But it really doesn't matter. Simply use the 2-blade setting & divide by 2.

Joel
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