Question about Wattmeters

[matiac]

Per the advice of a few folks here and at other forums, I got myself a AEO Wattmeter for use on my big plane. My question, having never used one before, is does it go between the battery and the ESC, or between the ESC and the motor? Is it something that's going to be permanently installed, or something that's "plugged up" for testing? The FMS planes have those elongated offset cylindrical plugs for the battery, can't seem to find them anywhere (have to put those on myself) before I can even think of using it. How exactly does one use this device, and the information I gain from using it?

[firemanbill]

Between your battery and ESC. And you just need to use it for testing and/or setup

A very valuable tool for sure!

[CHELLIE]

HK-450 Bench Test with Watts Up Meter

[firemanbill]

Does it use these?

http://www.hobbyking.com/hobbyking/s...arehouse_.html

[CHELLIE]

Turnigy Precision Watt Meter and Power Analyzer

[rcers]

Remember the in-line meters cause issues for ESC's, so short runs only! I usually do less than 15 seconds, and NEVER more than 30 seconds.

5-10 seconds are enough for the vast majority of tests. Just enough time for readings to normalize.

Shunts or clamp meters can be run for longer times.

Mike

[CHELLIE]

Great Reading

http://www.wattflyer.com/forums/show...ight=wattmeter

[kyleservicetech]

Originally Posted by matiac

Per the advice of a few folks here and at other forums, I got myself a AEO Wattmeter for use on my big plane. My question, having never used one before, is does it go between the battery and the ESC, or between the ESC and the motor? Is it something that's going to be permanently installed, or something that's "plugged up" for testing? The FMS planes have those elongated offset cylindrical plugs for the battery, can't seem to find them anywhere (have to put those on myself) before I can even think of using it. How exactly does one use this device, and the information I gain from using it?

Yup, as others have posted, between your battery and ESC! The signal between the ESC and Motor is AC (alternating current) so if you connected the wattmeter there, it won't work, and could damage it.

FYI, these wattmeters use precision very low value shunt resistors with limited wattage ratings. They may not be designed for continuous duty. Putting one of these wattmeters in the battery circuit permanently might burn up that shunt.

The Castle Creations ICE series, and a few other brands of ESC's do provide data logging, allowing you to download flight data after a flight, or number of flights. The CC ICE ESC provides watts, volts, amps, RPM, ESC temperature and a few other things.

[matiac]

Originally Posted by firemanbill

Does it use these?

http://www.hobbyking.com/hobbyking/s...arehouse_.html

Ok, have plugs (WHY didn't I see those before?), Thanks for that, and only use it long enough to get a reading. Got it. So the info gained would determine whether a bigger ESC is needed, or leave well enough alone? Obviously it's measuring draw from the battery in Watts, I believe mine does amp draw too...I got some reading to do...

[firemanbill]

Originally Posted by matiac

Ok, have plugs (WHY didn't I see those before?), Thanks for that, and only use it long enough to get a reading. Got it. So the info gained would determine whether a bigger ESC is needed, or leave well enough alone? Obviously it's measuring draw from the battery in Watts, I believe mine does amp draw too...I got some reading to do...

Yeah watts and amps. You can play with different props to see how it changes the draw for one thing. If you want to go with a bigger prop for more oomph so to speak, the watt meter could tell you if you are still within the parameters of the esc or not.

Just one example of the many things it is good for.

[kyleservicetech]

Originally Posted by matiac

Per the advice of a few folks here and at other forums, I got myself a AEO Wattmeter for use on my big plane.

How big of a plane

If you're running motors with perhaps 1000 watts or more, take a look:

Just put the maiden three flights on this model last week, before we got more snow:
http://www.wattflyer.com/forums/showthread.php?t=68844

And, more reading stuff.

Great Planes Giant Big Stick Electric Conversion
http://www.wattflyer.com/forums/showthread.php?t=65052

Giant Scale Cessna Model
http://www.wattflyer.com/forums/showthread.php?t=66414

Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222

Hacker 6S2P A123 powered Models
http://www.wattflyer.com/forums/showthread.php?t=44686

AEAJR's Site on Electric Power
http://www.wattflyer.com/forums/showthread.php?t=18521

[matiac]

It's my FMS 1400MM P47. Since the addition of the Orange, it was explained to me by...you I believe that I should monitor that sort of thing, as the gyro will be making the servos do "double-time", and I should keep an eye on that. I also want to put something in the line with the flaps to slow them down a lot, right now if you hit the toggle, they come down, like, right now, and I would like to slow that down a tad, not only to look more scale, but it seems to me if they deploy that fast, I envision my plane nosing up at an alarming rate...someone told me about a gizmo I could get for it, but I can't for the life of me remember what it was called, or even who to get it from...a servo specialty shop online??

[firemanbill]

Yeah it'll come in handy to monitor the extra workload.

Some radios can slow down servos internally without extra gadgets. My JR 9303 has an option to do just that on the servo flap. You can program various amounts of delay in there to slow down the travel. The do make gadgets for it though if your transmitter won't do it.

http://www.hobbyking.com/hobbycity/s...idProduct=8863

I hate to keep posting links to hobby city, but that was the first one to pop up. There are other brands out there too!

[matiac]

Originally Posted by firemanbill

Yeah it'll come in handy to monitor the extra workload.

Some radios can slow down servos internally without extra gadgets. My JR 9303 has an option to do just that on the servo flap. You can program various amounts of delay in there to slow down the travel. The do make gadgets for it though if your transmitter won't do it.

http://www.hobbyking.com/hobbycity/s...idProduct=8863

I hate to keep posting links to hobby city, but that was the first one to pop up. There are other brands out there too!

That's exactly what I need! I can do retracts AND flaps, cuz the retracts are kinda fast too...just don't look right. Page bookmarked, THANKY for that!

[firemanbill]

No problem. Like I said, I do not work for Hobby City, they just seem to have everything! LOL

[matiac]

OK, had to go to LHS for the proper plugs, have some reading to do, Thanks to Chellie and Kyle for the links, if not for this, and other forums, I'd be a "babe-in-the-woods"...or at least MORE than I would be without any of this info...STAY TUNED...gonna grab one of those servo reducers from H.K. too, thanks to H.K.'s plugman...just kidding, I shop there so much, C.S. KNOWS me...

[firemanbill]

LOL

[Dr Kiwi]

Originally Posted by rcers

Remember the in-line meters cause issues for ESC's, so short runs only! I usually do less than 15 seconds, and NEVER more than 30 seconds.

5-10 seconds are enough for the vast majority of tests. Just enough time for readings to normalize.

Shunts or clamp meters can be run for longer times.

Mike

Mike, I'm puzzled... my typical test series for motors [and I've bench tested hundreds] comprises bursts to WOT for maybe 15 secs (just enough time to record the data..volts, amps, watts, rpm, thrust)... but every now and again, to push the limits I've run at WOT for 2 minutes or so (until motor temperature approaches 50C-60C.. then I shut it down). I use a Medusa Analyzer Plus in-line between PS and ESC. What are the issues for the ESC in doing this?

Cheers, Phil

[rcers]

Phil - the issue is two fold. Heat and the extension of the battery wires. Heat kills electronics - that one is easy. Since your two minute test is to see what heat the motor climbs to that is valid. But you measure the heat and I assume stop the test before the motor melts. Most guys don't do that and I have read many posts where guys do a "ground" test for 5-6 minutes and the wonder why their ESC or motor or battery cooked.

Extension of the battery wires increases voltage ripple and the ESC has to cope with that.

For most setups - the increase of wire isn't that big a deal, but it can cause them stress especially the cheap ones. The caps on ESCs are there to smooth that voltage out.

You will NEVER see the guys with high power systems do in-line watt meters for this reason. Most of them shorten the wires to as short as practical for use. When then test power consumption they either use a clamp meter or shunt attached to a meter.

Mike

[kyleservicetech]

Originally Posted by rcers

Phil - the issue is two fold. Heat and the extension of the battery wires. Heat kills electronics - that one is easy. Extension of the battery wires increases voltage ripple and the ESC has to cope with that.

For most setups - the increase of wire isn't that big a deal, but it can cause them stress. You will NEVER see the guys with high power systems do in-line watt meters for this reason. Most of them shorten the wires to as short as practical and they use a clamp meter or shunt.

Mike

Yeah, for those larger models, (or for any electric model), check out the Sears #82369 digital AC and DC clamp on ammeter. It's on sale now for $51 through the web. Note that most clamp on ammeters are AC only, not useful for our electric stuff. It measures either AC or DC current in a 0-40 or 0-400 Amp range, plus the usual volts, ohms, temperature and a few other things.

I've got one, and it stays with the transmitter carrying case.
http://www.sears.com/craftsman-digit...1&blockType=G1

[solentlife]

It's OK saying nothing more than 10secs or so to protect the ESC ... but tests show that results are in error until power train has run longer and settled ...

I've run longer tests - and at no time have I lost or damaged a set-up. But do admit that usually I'm just looking for max amps to make sure I have right ESC and to calculate best LiPo size for job.

People talk about Shunts ... but majority wouldn't know what to do with one !!

Nigel

[kyleservicetech]

Originally Posted by solentlife

People talk about Shunts ... but majority wouldn't know what to do with one !!

Nigel

Yeah, I've got a couple of 50 Amp, 0.5% accuracy four wire current shunts, rated for continuous duty. They weigh about a half pound each.

[rcers]

Originally Posted by solentlife

It's OK saying nothing more than 10secs or so to protect the ESC ... but tests show that results are in error until power train has run longer and settled ...

I've run longer tests - and at no time have I lost or damaged a set-up. But do admit that usually I'm just looking for max amps to make sure I have right ESC and to calculate best LiPo size for job.

People talk about Shunts ... but majority wouldn't know what to do with one !!

Nigel

I agree but I have noted that my numbers always settle within the first 3-4 seconds. After that the numbers just consistently drop, as expected with voltage drop.

That first few seconds I ignore but rarely find the need for more than 10 seconds.

Mike