Medussa data logger vs Eagle Tree Logger

[tjrtmaster]

I have almost no knowledge about either one of these devices but I think one of them could be a good Christmas present. I have a Medussa motor. How does the Medussa logger compare with the Eagle tree in features and cost?

Thanks,
Tim

[aaron07]

I'm interested in this comparison as well, maybe post it in the Main Forum - Helicopter Talk.

[Pinecone]

If someone will send me a Medusa logger, I will be happy to compare it to the Eagle Tree V2 and V3.

[tjrtmaster]

What is the cost of the Eagle Tree Logger? Do you have to attach a magnet somewhere with the Eagle Tree so it can read RPM's?
Tim

[Skiddz]

I think the E3 is around $70 and add $40 for the power panel (Not necessary though)

RPM sensors come in magnetic, optical and a brushless motor sensor. The software lets you tweak the appropriate values to work with the various RPM sensors.

www.eagletreesystems.com

[TX HM-52]

I have a broken "Brand new" Eagletree logger that I'm throwing away rather than send in for service due to the horrible customer service! I've never been so mistreated by a manufacturer, time wasted then they tell me when I say I'll call the BBB and post about the bad service they actually had the balls to tell me I was "extorting" them !

I've thrown out my V2 and will now be purchasing the medusa or one of these others I've found that have to have better service!

http://www.teamnovak.com/products/da...try/index.html

http://www.bnbproducts.com/

http://milehighwings.com/index.php?cPath=30

These are just a few great alternatives I've found and my experience with them was so bad I wouldn't let my enemies buy Eagletree! The only thing I can't find (yet) is an onboard LCD display like ET's power panel, but that's what never worked on mine even after 3 months of BS going around and around with tech support then they lied and didn't even give me a cros sship as promised after waiting so long!

Please, If you like your money and want service buy any brand but Eagletree!

Mike

[ke6d]

Originally Posted by TX HM-52

I have a broken "Brand new" Eagletree logger that I'm throwing away rather than send in for service due to the horrible customer service! I've never been so mistreated by a manufacturer, time wasted then they tell me when I say I'll call the BBB and post about the bad service they actually had the balls to tell me I was "extorting" them !

I've thrown out my V2 and will now be purchasing the medusa or one of these others I've found that have to have better service!

Mike

My experience with them has been the contrary. I bought the recorder V2 from a local hobby shop for $70. I was pretty happy with it. One week later Eagle Tree announced the V3 with better bells and whistles for the same price I called them up to complain. The rep to me that Eagle Tree has a 30 day free exchange policy. She also told me that since the new version would not be available until late November and advised me to keep the old recorder and only send it in a few days before the 30 days limit.

I did just that. My new recorder showed up last week.

Thank you Eagle Tree.

Dan

[TX HM-52]

Well actually thats why I'm so upset... I purchased my new V2 30 days before the V3 was supposed to be released since I needed to make measurements now (even though I really wanted the V3) and then after getting it I tried for three days to reach them by phone (forget that) they work the phone some silly hours like 2- 2 hour blocks 3 days a week so then I went to their forum at RR and then got the runaround for a week, then they started deleting my posts when I talked about the bad service experience . While promising me a crosshipped replacement , then a week later they told me they wouldn't do that... So I was left with a non working V2 logger after the V3 (same price nearly) was released, they told me (after I explained how long this had taken and how I wanted to pay to upgrade to the V3) THEY TOLD ME THEY WOULD ONLY GIVE ME A $10 CREDIT!!!!! These guys are crooks and liars!

Mike

[Big Fil]

Send your broken logger to me. I'll make use of it.

[bugdozer]

Originally Posted by TX HM-52

I have a broken "Brand new" Eagletree logger that I'm throwing away rather than send in for service due to the horrible customer service! I've never been so mistreated by a manufacturer, time wasted then they tell me when I say I'll call the BBB and post about the bad service they actually had the balls to tell me I was "extorting" them !

Mike

Sorry to hear you had such a problem with them. All my experiences have been outstanding. My fist V2 puckered out during a firmware update. I called them and got an engineer on the phone that had me try a few things that did not work so he sent me a replacement that I had in my hands two days later. I ask him what to do with the failed unit and he said to trash it rather that wast my time and money shipping it back.

During another phone conversation with EagleTree, I mentioned that the location of the Download and Clear Recorder buttons on the software seemed a bit off, the Clear button was on the left with the Download button in the middle. I asked if they could swap the two buttons so, working from left to right, you hit the Download button first and then the Clear button. I felt if flowed better. Two version releases later, the button locations had been swapped. I'm sticking with EagleTree although I have not tried another type.

[Pinecone]

My experiences have also been very good with them.

I contacted them about a couple of sensor ideas and at least one is in the works. Logging voltages to track down Spektrum reboots.

I emailed about a rebate/upgrade deal and they told me about the $10 (I bought mine in March) and even sent me a PDF copy of my V2 invoice so I would have it.

[Pinecone]

Originally Posted by tjrtmaster

What is the cost of the Eagle Tree Logger? Do you have to attach a magnet somewhere with the Eagle Tree so it can read RPM's?
Tim

You can use magnets if you want (makes great sense on a nitro ship running governor magnets), optical (you could paint light and dark patch on the main shaft), or coolest using a sensor that reads the ESC pluses to the motor. You tap one motor wire and connect that to the sensor. Tell the sensor the gear ratio and it will log the headspeed.

I put a thin wire with a servo socket onto one of the wires from the ESC and with each new ESC as I put the bullets on it.

[TX HM-52]

reading RPMs from the ESC can be inaccurate as opposed to actual shafts since it's only measuring the pulses sent to the motor and takes no mechanical drag or other possible problems into account and it will still read what the ESC thinks it should be doing.

[bugdozer]

Originally Posted by TX HM-52

reading RPMs from the ESC can be inaccurate as opposed to actual shafts since it's only measuring the pulses sent to the motor and takes no mechanical drag or other possible problems into account and it will still read what the ESC thinks it should be doing.

True, true. If you just enter your calculated ratio, 11.54:1 for 150/13, the logger if off by a few hundred RPM's. Real nice thing about the EagleTree is you have the ability to fine tune it in live mode. On the bench, I use an optical tach to set my head speed to, say, 2800. Then you tweak the ratio in the logger to match the tach. 12.52:1 is dead on for my setup. You can also use a volt meter and an AMP meter and fine tune the voltage and AMP draw if you are so inclined.

[TX HM-52]

Originally Posted by bugdozer

True, true. If you just enter your calculated ratio, 11.54:1 for 150/13, the logger if off by a few hundred RPM's. Real nice thing about the EagleTree is you have the ability to fine tune it in live mode. On the bench, I use an optical tach to set my head speed to, say, 2800. Then you tweak the ratio in the logger to match the tach. 12.52:1 is dead on for my setup. You can also use a volt meter and an AMP meter and fine tune the voltage and AMP draw if you are so inclined.

Assuming you calibrate it with an optical tach at install (the way I did and would imagine anyone doing) the reading can be completely erroneous if something mechanically changes or starts to fail or bind then the tach connected to the ESC will have no clue what the actual headspeed is/ only what the ESC is outputting.

I would recommend a hall effect (magnetic) or optical then this is not an issue.

[bugdozer]

Actually, it's very accurate this way. The sensorless ESC only work because it monitors the pulses coming back on the motor leads as the magnets in the motor pass the windings. This is the only way the ESC could know what the motor was up to and give it the ability to control it's speed. The logger watches these pulses to calculate the motor RPM. The ESC and the logger know exactly what speed the motor is operating at. That is also why it is important to enter the correct number of poles in the logger set up so it know how may pulses to count per motor rotation.

[TX HM-52]

sorry but this is not the case, the logger simply monitors the PWM coming from the ESC to determine what the speed "Should be" assuming nothing ever changes. I write PIC micro controller software for this very Microchip PIC 18x / 16x series and I know exactly how it's done and how I would accomplish it. I even asked a senior tech at Eagletree (in my many, many conversations with them) and he agreed so you can always ask them if you don't believe me. I wouldn't kid you.

This method does work fine assuming you calibrate it with a real tach and NOTHING ever changes mechanically like drag etc. and that is the issue.

You should be able to verify this by disconnecting the motor from the ESC while the logger is measuring RPM (and still connected to the logger) and it won't know the difference (assuming they still see the same pulse on all phases of the motor without it's resistance and that depends on the hardware design even then you could throw a resistor on it to simulate a motor's Impedance).

Edit: as far as entering the # of poles this is simply used as a divisor in the formula for determining the speed since the monitor is only connected to a SINGLE pole/phase.

Mike

[bugdozer]

Ok, that makes sense but isn't the PWM changed by the ESC as the motor slows or speeds up during flight in order to keep the motor running correctly? If that was the case, the logger will see the change in the motors RPM's. I have a basic overview of the brushless ESC function but have never delved in that deep. I guess what really matters is the logger is accurate enough for what we are doing and is seems to be. Thanx!

[TX HM-52]

Governor modes on an ESC is something I hadn't thought about, I would be curious to know how they accomplish that. It must have something to do with percentage of load (current based) that the controller sees the motor draw internal to the ESC then applies a fairly complex calculated/predetermined percentage of increased PWM to maintain near the desired speed on the motor.This apparently is not what eagletree and others do to detect speed (party to keep complexity and cost down as ridiculously low as it is I would think) I'm pretty sure they use the simpler method of just looking at the pulse modulation to the motor since the guy I talked to there agreed it could be off if mechanically dragged after calibrated when we discussed the best tach method at length.

optical is a real pain in the butt to get to work due to external light and interference from vibration etc. and magnetic is also a pain to keep mounted if replacing shafts etc. I think for most people the ESC method is just fine, just not for me personally.

well, I'm off to break some blades.. I mean fly

Regards,

Mike

[tjrtmaster]

Does anyone know where I can get a Medussa Data Logger?

Tim