747

Hi
I am getting into EP deeply now....since my car smells of Glow fuel spills more now.. LOL!

Where can I get a nice cheap RC voltmeter? How about walmart/HD/radioshack etc?

What functions do I need for EP flight?
Should I get a Multimeter instead for all future EP purposes? Even household purpose? If so whats a good brand that is not expensive?

thanks !!
747

CHELLIE

Hi 747 you need a Wattmeter and so do I here is a nice one, If you are only looking for a digital volt ohm meter, here is a nice one for $2.99 at harbor freight tools, Chellie

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXLMV0

http://www.harborfreight.com/cpi/cta...emnumber=90899

747

Chellie!
So this is capable of measuring all the important stuff in RC EP class?
I thought a cheap multimeter frm radishack is all I needed.
Is it portable with just 2 leads?

CHELLIE

we need both, wattmeter and volt ohm meter, the volt ohm to check, battery current, shorts, winding draw, etc, and wattmeter to check final draw during use.

Sir Raleigh

The watt meter is also good for checking charge current and voltage. A VOM is difficult to put in series due to the various connectors on the batteries, chargers, ESCs, etc., but a watt meter just plugs right in and gives you all the readings you need at one time (assuming you have the same connectors on the watt meter as you do on everything else).

Also, a VOM usually will not measure amperage above 10 amps.

747

Hi, I didnt understand that part(bolded).
Do Watt meters have 2 leads that I can touch battery power lines,resistors etc to measure?..in parallel? Coz I thought all measurements were parallel only which is easy right?

Plus if this gives every basic measurement thats needed I will get it. Am I better of buying from Tower or will the same caliber wattmeter be in avbl local stores Like RS,HD,WM,CCity etc
tks--747

slipstick

Wattmeters have 4 leads, 2 in and 2 out. That's because you cannot measure everything in parallel. It isn't possible to measure current without inserting the measuring device IN SERIES in the circuit (or using something expensive like a contactless clamp ammeter).

Steve

Biplane Murphy

I have a "Watts-up" wattmeter....it plugs in "in between" the Battery and ESC.....It gives all the necessary info all at once... and is even small enough to send up in the plane if the plane is a decent size.....

You have to solderon connecters to the meter....and you can make adapters to use for other applications.

It is the one that CHELLIE linked to with the Tower hobbies Link......I had my Local Hobby Shop order it for me.

747

SO to measure I would plug it "in between" the Battery and ESC without disconnecting the batt to esc line right? Then after measurement i can take it out?
Can I use it for measuring each cell in a lipo/a123, household electronics too..the concept that it doesnt have a power source bothers me!

I wanna measure only before flight right? I dunno if this is what I need or a simple cheap Voltmeter like Chellie suggested (for now as i'm entering EP - but spending all the time on the net LOL)!

Biplane Murphy

You plug the wattmeter into the ESC and then the Battery into the Wattmeter...The Flight Battery is the power source.

After the measurements and tests....you disconnect everything and hook the Battery back up to the ESC as usual....

This Wattmeter is small enough to run in your Rascal in-flight....And when you land it will give you info such as watthours used...amps used...minimum voltage during flight ...max watts during flight etc....

Also if you want extremely accurate readings you can plug in a seperate nicad Rx Battery into the wattmeter via an extra port for just that purpose......That gives the wattmeter it's own power source.

You could probably use the external Rx Batt power source, and make a set of probes for checking individual cell voltages.... I don't think that using it for household stuff is a good idea since it can have inputs of 0-60 volts.

You can get a Multimeter for cheap at Radio Shack... I bought a decent one there for about $6.00 on sale............

Biplane Murphy

Also..... Measure during ground tests to see amp draw and watts ....Before flights for charge condition of battery...after flight for voltage of battery....and if left in line in the plane during flights it will provide a wealth of info.

Sir Raleigh

I think you are expecting too much from a device that's designed for a specific purpose.

• It plugs in between the battery and ESC.
• You do need to disconnect the battery to ESC line, that's how it's connected.
• Yes, you can take it out after you are through using it.
• No, you can't use it to measure each cell of a battery pack unless they are separated from the pack, it measures the entire battery pack.
• This is not a general purpose instrument, you will need a DVM or VOM to check things around the house.
• The power source is obtained from the battery you plug it into.
• You can measure voltage before and/or after each flight. However, it really doesn't do much good to measure the voltage of a NiMH battery after a flight because NiMH batteries maintain full voltage until the last few minutes of its capacity, but Lipos can be measured after a flight to get a reading of what capacity is left in the battery. It will act as a sort of fuel gauge.
• A cheap DVM or VOM will not give you the most critical information you need when flying electric planes which is watts. This must be obtained either from a device designed for that purpose or through mathematical formulas, of which the watt meter is the easiest.

jasmine2501

No, the cheapo multimeters from Radio Shack can't measure the amps we need to measure. Yes, the "Watt's Up" meter will tell you everything you need to know, with the exception of RPM.

FlyWheel

If I may "butt in" to this conversation, I need a little clarity. When you say the What's-up meter will tell you everything, does that mean I will not need any other meters? For RC, I mean, not checking my refridgerator.

Biplane Murphy

Yes....for the most part....You do need to make a few "adapters" to do some stuff... However I do still use my Multimeter to check individual cell voltages......

Also the "Watts-up" meter does it all on one screen with no buttons to push......

Bill G

I keep a cheap voltmeter in the rc box, for the field. Good to have, since it give the basics, and I don't feel like hauling around the wattmeter.
One thought: Analog meters will still read voltage when the battery is shot, when digital meters do nothing then. Analogs often use cheap AAA batts, which we all have. Small digitals take 357's, which we usually don't keep around the house, and cost more. My dang digital accidently got turned on, and burnt out a set of batts that I just replaced. I just replaced them again. The cheap "protector" cover had torn, so it got turned on in my glovebox. You can bet I made a cheap cover with plastic sheet and clear tape, so it dosen't happen again.

Sir Raleigh

I found a pack of 6 (or maybe 8, I don't remember) 357 batteries at the Dollar Store for... you guessed it... $1.

FlyWheel

Thanks. By "adapters" I Ass-U-Me you mean the for the connector plugs? I have Dean's Ultras on all my RC stuff.

Biplane Murphy

Yep.....you have to solder on deans connectors.... and if you make adapters to hook it up the other direction, you can plug it between the Charger and the Battery and get readings of how much energy is put back into the battery....
And other such applications....The Watts-up is a very useful device.

ELECTRICTIGER

747-- BUY the watt meter- they are only around $50. and, as was stated on another post, will pay for itself many times over the first time it discovers a mistake you are about to make instead of frying equipment.you will also KNOW if your prop/motor /sc is correct & efficient.