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Old Apr 26, 2012, 08:14 AM
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Bill Smudge's Avatar
United States, KY, Bowling Green
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Anybody use this wattmeter? Multi-function Wattmeter FD-WM

Hi Guys,

I came across this wattmeter on Ebay, I'm trying to get some opinions about it. Anybody out there have any experience with one?

http://www.ebay.com/itm/150633905792...84.m1438.l2649


Thanks Much,

Bill


Ok I bought one review on last post
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Last edited by Bill Smudge; May 18, 2012 at 07:53 PM. Reason: I bouhgt one reveiew on last post
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Old Apr 27, 2012, 02:32 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
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Hi Bill, I've never used it but here's my comments FWIW.

Rated for 100A, however, I don't see a spec for how long. The absence of any
visible heat sink of any size would make me think the time limits are pretty short.
You might question the seller for that info.
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Old Apr 27, 2012, 10:33 PM
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Canada
Joined Nov 2000
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HK sells a sim gizmo.
Bought one it was DOA, "finally' got a warranty claim.. Replacement half works
Caveat Emptor Kids.
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Old Apr 28, 2012, 07:57 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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So that is just for real time display, right? It does not record any data or anything? And I guess silver cylinder is the thermal probe?

As always, cheaper is an attractive quality. But I already have an eLogger and that brings up a need for it to also be viewed in comparison to that. This looks like another case where cheaper and better (or even as good) are mutually exclusive qualities.

Jack
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Old Apr 28, 2012, 08:40 AM
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Bill Smudge's Avatar
United States, KY, Bowling Green
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Quote:
Originally Posted by jackerbes View Post
So that is just for real time display, right? It does not record any data or anything? And I guess silver cylinder is the thermal probe?

As always, cheaper is an attractive quality. But I already have an eLogger and that brings up a need for it to also be viewed in comparison to that. This looks like another case where cheaper and better (or even as good) are mutually exclusive qualities.

Jack
Hey Jack,

I'm cheap, what can I say

, but it is fairly small, you can send it up with some planes.
You never know about some of this stuff until somebody trys it....it does have a temp prob (for what that is worth), it just looks halfway neat to me.

I'm hopeing for some first hand usage feedback.

Woud be nice if we could get a comment from somebody that has one.


May be a better than just a real time display, here is the "manual":

I might bite the bullet and buy one and give a review of the darned thing!!

Bill

FD-WM Manual



Features
The FD-WM is a style of miniature multi-function wattmeter, which is small volume and lightweight. It can be used on the R/C model to check the real-time current, voltage, watt and temperature, and also it has a battery voltage acoustic-optical alarm function, It can also record the maximum current, watts ,temperature and the minimum voltage. Users can easily understand their R/C power system via this item.

Specifications
FD-WM Voltage (V) Current(A) Temperature (℃)
Dimension:8029.47.9mm Measuring Range:7.4~45v (2~10s Lipo) Measuring Range:0A~100A Measuring Range:-20℃~100℃
Weight: 25.6g Resolution:0.1V Resolution:0.2A Resolution:0.1℃
Joint: T type Alarm Range:4.0V~49.9V Alarm Range:3A~99.9A Alarm Range:20℃~89.9℃
Packing: Plastic Initialize Alarm:9.9V Initialize Alarm:20A Initialize Alarm:50℃

LED State
All LEDs off: Wattmeter displays scrolling voltage, current, watt values and temperature.

V LED on: Displays real-time battery voltage.
A LED on: Displays real-time battery current Amps.
W LED on: Displays real-time battery output power in watts.
C LED on: Displays real-time temperature.
The corresponding LED will flash while alarming, and buzzer keep the beep ring
Operation
1. Connect the Wattmeter between the battery and the ESC. It will read the real-time voltage,
current, temperature and calculate watts. Press the right key each once, the wattmeter will change
between above states.
2. Press the left key, the wattmeter can get the minimum voltage, maximum temperature, current
and watts of this flight.

3. Press the left button more than five seconds in any state, the wattmeter will go into the alarm
setting state, via the right key to set the alarm extreme value, and then press the left key to confirm
and the right button for increasing, setting succeed, then press the left key to exit setting.
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Old Apr 28, 2012, 09:09 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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OK, reading the manual has it sounding better already. It will probably remember all the data summaries mentioned until it is disconnected from the battery and that is good enough for a lot of purposes.

The temp probe would probably be good for taping to a battery pack but not so good for getting it to the windings or base plate on a motor.

It's another gadget that works out on OK when you can find a good use for it.

If you look at the eBay seller's listings, he has some other interesting RC stuff too.

Jack
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Old May 18, 2012, 07:52 PM
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Ok I bought one, looks pretty good!!

I got a chance to talk to a couple of fellas that bought one of the

Multifunction Wattmeter FD-Wm on Ebay, they had a pretty good review of the little wattmeter. I ordered one on May 8th and it got here today China Airmail, 10 days, not bad at all!!

The little widget has pretty good functionality, will scroll display battery volts, amps, watts and temp probe temp. Or you can lock the display on any one of the four items and read it real time. Also it remembers the highest peak reading during a run and will hold it until cleared.

Weighs 28 grams with temp probe and 26 without. You can send it up with larger planes to record peak readings, you can see its not too big using my hand for a reference.

Last but not least it can be set to alarm on low voltage, over current, over wattage or overtemp. Turns on a little beeper when that happens.


I have to say for $18.93 looks to be a pretty darned good deal...., that being said I have no idea how accurate the readings are but for my use it should more than suffice.

It can be found here if interested, this is the place I got mine in 10 days.

http://www.ebay.com/itm/Multi-functi...item1e6c4aa2d8


Best to all,

Bill
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Old May 19, 2012, 08:27 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Looks like a good one, Bill.

The temp probe is detachable, right? If you can use an multimeter and measure the resistance across that (it is a thermistor I think) you may find that you can make your own better and smaller temp probes and with longer leads. That will let you put them into places like the cooling slots on a brushless motor.

You read more about that here:

DIY Sensor for EagleTree eLogger.... - http://www.rcgroups.com/forums/showthread.php?t=1526363

Jack
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Old May 19, 2012, 08:47 AM
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Bill Smudge's Avatar
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Quote:
Originally Posted by jackerbes View Post
Looks like a good one, Bill.

The temp probe is detachable, right? If you can use an multimeter and measure the resistance across that (it is a thermistor I think) you may find that you can make your own better and smaller temp probes and with longer leads. That will let you put them into places like the cooling slots on a brushless motor.

You read more about that here:

DIY Sensor for EagleTree eLogger.... - http://www.rcgroups.com/forums/showthread.php?t=1526363

Jack
Yes Jack, the temp probe comes off, reduces weight by about two grams..

Thanks for the DIY sensor link.

Bill
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Old Sep 19, 2012, 05:26 PM
Jack
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Joined May 2008
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Bill,

Have you been using that? Maybe you can answer a couple of questions?

Does it remember the highest values for V, A, W, and C and can you review those at the end of a flight?

And if it is powered off and back on will it remember the last recorded highs?

Or does it clear and reset itself on each power up.

Thanks for the help on this interesting little device.

Jack
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Old Sep 19, 2012, 06:29 PM
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Quote:
Originally Posted by hoppy View Post
Rated for 100A, however, I don't see a spec for how long. The absence of any visible heat sink of any size would make me think the time limits are pretty short.
It appears to be using an Allegro 100A hall sensor, which has a shunt resistance of 0.1 millohm. At 100A the Deans connectors will heat up more than the sensor!

LEDs draw a fair bit of current, so hopefully it has a switched mode regulator to power the display circuit.
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Old Sep 19, 2012, 09:28 PM
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Bill Smudge's Avatar
United States, KY, Bowling Green
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Quote:
Originally Posted by jackerbes View Post
Bill,

Have you been using that? Maybe you can answer a couple of questions?

Does it remember the highest values for V, A, W, and C and can you review those at the end of a flight?

And if it is powered off and back on will it remember the last recorded highs?

Or does it clear and reset itself on each power up.

Thanks for the help on this interesting little device.

Jack
Hey Jack,

Yes I have been using fd-wm, yep it does remember the peak values of each powered on sesion--- V, A, W, and temp, you can review them after a flight or test sesion. It has complete memory loss after the battery is disconected (hey what do ya want for 18 bucks), even can be set to alarm on low voltage, etc.

I think it's quite a steal, to date I've never sent it up with a plane, but I could on some of my larger ones. I just use it for prop testing and current testing.

I'm surprised more folks haven't picked up on this little jewel.

Bill
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Old Sep 19, 2012, 09:34 PM
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United States, KY, Bowling Green
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Quote:
Originally Posted by Bruce Abbott View Post
It appears to be using an Allegro 100A hall sensor, which has a shunt resistance of 0.1 millohm. At 100A the Deans connectors will heat up more than the sensor!

LEDs draw a fair bit of current, so hopefully it has a switched mode regulator to power the display circuit.
--------------------------------------------------------

Bruce your right I've never noticed any heat out of the device while testing motors, that being said I've never had current running through the device for any length of time. I need to give that a try and report back.

Bill
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Old Sep 19, 2012, 09:52 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Thanks, Bill.

it was more a case of curiosity for me. I have the eLogger and that records, has an PC application, and the other bells and whistles. But FD-WM would be good for quick measurements in the field and stuff.
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