Hello everyone,

Does anyone know of a reasonable ampmeter for testing the current draw on our electric motors? It would need to be approx 1-30 amp.

Thanks

Sears Model #82062 I believe was less than $40. Work well and its a clamp on so its also easy.

Or if this helps: http://www.sears.com/sr/javasr/produ...id=03482062000

It is also $49.95

There are a few different products on the market especially for R/C use now. Take a look at the AstroFlight Whattmeter for $60. Maxx Products has a similar device, though not quite as sophisticated, for $40-$50.

Thanks for the suggestion, BUT, that Sears clamp on does not do DC amps only AC. I already have an expensive AmpProbe clamp on ampmeter, does Ac amps only, relies on induction.

Matt, Thanks for the heads up on the Astroflight & Maxxproducts. I will check them out.

CRS

I went to auto zone and got a car amp meter that reads 0-60 amps,+ or -,in 10 amp steps.I need a 30 amp meter for lower amps.

Foo,

Thanks, I have already been to the discount auto stores, but Those ampmeters are not acurate enough for me.

I want a more calibrated diarsenval movement meter with a shunt.

Randy

CaptainRandy,

Actually, the clamp-on meters DO work, especially on brushless motors. There is never a constant flow of current through the wire between the ESC and motor on a brushless motor; it's always pulsing, which is what the clamp-on meters need.

They even work on brushed motors, to a point. As you get close to full throttle, the pulses to the motor get too close together for the meter to read. Other than that, it's surprisingly accurate.

I have a Whattmeter and a $10 Harbor Freight clamp-on meter. Haven't used the clamp-on in a while, but when I tested it, it was within 1/2 Amp of my Whattmeter.

Hey Matt,

I have an AmpProbe clamp on meter, but I thought that is was only for ac or pulsing dc maybe. Straight dc would not have any induction, so I don't see how it would work.

I am going to see if they sell a shunt for it or for my Simpson 220p.

Thanks

The Sears clamp on does both AC and DC and is accurate. I take my readings from the lead coming off the battery. I read a comparison between this and the astroflight and they were only .2 of an amp different in all the test.

I think the difference between the old clamp-on AC only ammeters and today's battery powered ammeters is that the new ones can indeed sense DC, pulsing or not. My experience is similar to INeedHelp's and I'm not measuring brushless motors.

But my old no-battery-needed clamp-on meter was indeed AC-only.

Any current flow through a conductor, DC or AC will generate a magnetic field according to the "right hand rule". Point the thumb of your right hand in the direction of current flow, and the curl of your fingers will indicate the magnetic field direction. I think you can hold a compass near your car battery cable and see this effect.

Unfortunately, this represents the sum total of my understanding onf this subject! Suffice it to say modern micro-chips are so sophisticated they can do whatever they please!

Chall, Thank You very much for explaining what the differences were.
That makes sense to me.
I have my eye on a beautiful old meter on ebay.
Thanks again, Randy

Just wanted to say Hi to Capt. Randy. I have such great respect for vietnam vets and all vets of course. Thanks for your service sir.

Randy on Maui

Hi Randy,

Thanks very much. We sure didn't get the welcome home that we all deserved.

We stopped in Hawaii on the way back from Viet Nam and my wife and I went on vacation there also. You live in the most beautiful state.

I am working on my 10 year old grandson to get him in the Navy.

Capt. Randy

foo, be VERY carefull using that auto ampmeter. I have one that goes to 60 amps. Have used it over a year. A couple months ago I hooked it to a Castle Creations PHX60/20cell set up. After doing some quick/short motor runs the controller fryed 4 FETS!!! I've been told that over 40-45 amps you can't use this kind of ampmeter, and I believe that. A $50 learning experience! The Astro Flight Watt meter is great. I now own a Medusa Power Analyzer Plus. You can hood the MPA plus to the computer run the motor and it will plot volts, amps, power (watts), watt hours & amp hours on individual graphs. You can change the prop, battery, gear, whatever & overlay the new test over the previous graph to see exactly what the difference is. Great tool? YES! Is it expensive? YES! $75-80, but well worth it I think. If I had it sooner, it wouldv'e saved me $50 (over half what it cost). But I'm sure it will save me money in the future (like from running lipo's over their recomended C rate). Happy fly'n to all!

i just used my clamp-on amp meter on my new brushless motor, i clamped it to one of the 3 lines and got a 7.4 amp reading. do i have to add up 7.4 amps times 2 or times three (to add up to all the wires?) or is the 7.4 amps showing in just one wire my total amps?