Using an RC Watt Meter | Quick Tip | Motion RC

[@charlesrestivo870]

Just came across this .Giving props to James .Simple and easy to understand

[@rusack7174]

Watt meters are also a great tool to keep an eye on pack health as they age by keeping an eye on voltage drop under load. As already mentioned by others, I always set up my models with a watt meter making sure I stay within motor maximum amp draw as well as making sure the chosen ESC has enough headroom above maximum draw from the motor as they also must provide power to the receiver and servos and possibly landing gear and lights, etc.

[@user-kikikiss]

You can use the watts to choose right motor. Every motor has limit of the output(watt). If you don't consider maximum output of motor, it will burn.

[@jeffhenderson934]

Good stuff James. I’m looking back like 5 years ago and knew nothing batteries or voltage meters. THANK GOD for the percentage (% left in the battery) Indicator. So, if you had done this video I’d still have all my original batteries! LOL! Thank you guys for putting this together.

[@50kArchipelagos]

Thanks man for those abbreviations meanings. I'm going through about five videos trying to find the most obvious thing a person would need to know. They want to talk about how it's got a rubbery feel and just weird stuff, everything but the data. It's been so long since I bought it I threw away the documentation and I never really wanted anything but the voltage until recently. I subscribed because you're a logical.

[@paulhatcher9767]

I too, have always had one, but haven’t took it out of the box. I will most certainly have to get some ends soldered on and try using it.

[@yodecaf]

This is very helpful. Being new to RC Planes, I didn't understand how much the prop's effect on my plane would be and never knew how to figure out what ESC to buy when building ARF's.

[@FL_Engineer]

I've seen a few vids on these but this is the clearest explanation

[@victorrcjets7660]

This will definitely help out a lot of new pilots wanting to experiment with this different power Systems. typically when you're running up an EDF you will see peak watts and amps vs what we call settled watts and amps this is after it's been running for a while. Your Peak is a voltage Spike that is what the resistors are for ways to help prevent overloading you're esc.

[@NoAgendaFPV]

I have one of these and never noticed the bottom left corner cycles through peaks. I have had a few cases i wanted to check what my peak Amp-draw was, but wouldn't be able to see it while running so didn't try it. Just learned I can run the device then go back and look at the peak before unplugging. Thanks!

[@mountaindewdude76]

Hi James! Thanks for this video! It looks like this watt meter is far superior to the watt meter that I've been using for quite a few years. I'll be looking for this GT Watt Meter, for sure!

[@jeffjackson6358]

Great video. I’ve never used one of these and it was nice seeing one in action.

[@garyvale8347]

I just bought this meter and package instructions are not clear ............ what exactly is the 3 pin slot on the " source " side of the meter is used for ? ....thanks

[@stephenthomas2311]

Thank you, James. Great 411 for the Knowledge Blog. Best, LB

[@DadsRCHangar]

I have one of these, but not used. This was really a great tip. Did not know about watts per pounds. Really a eye opener. I will have to go and play with mine.

[@txkflier]

www.rc-airplane-world.com/watts-per-pound.html

[@DadsRCHangar]

@@txkflier thanks for that link. Will have to read over that 👍🏻

[@laurenceboag2325]

That was great! It answered some important questions for me. Thanks!

[@M0rdH0rst]

Ordered one 😀 If there is enough space in the plane, you could just put it in there and check the maxima after the flight.

[@MotionRC]

Definitely, but for the most part, your maximum in the air will never exceed what it is static.

[@gerardpayne6902]

Good video, thanks. Does anyone know if you can charge the battery through the wattmeter so you can measure the Ah going into the battery? Will the meter show negative numbers in this case or do you have to reverse the source and load?

[@txkflier]

I’m surprised the current and watts were higher for the 9 blade. But, we don’t know if the blade angles are the same. I wish the manufacturers would provide the blade angle/pitch info..

[@bigeclipse718]

Less blades are more efficient but they don't sound as good.

[@amanite5845]

Is there anyway to lock the mAh value in the display?

[@ajayjoseph4498]

Can you log data?

[@Electron_master]

Hey, can I use it for 60v battery in an EV scooter where the max battery volltage is nearly 68V.

[@darkofc]

👍😊 Happy New Year James and motion RC crew ! Excellent job - you just saved me a lot of explanations ..👊 If that was your plan - I like the one point at the time approach .. Nice follow ups would be balancing and thrust measuring (to have all in one place for newcomers ..) (more complex items - correlation between kv,V, blade counts, ducting etc, - could be in some future "Advanced" series ..) P.S. I am also forever grateful to gooniac, Herb and 4stripes for my initiation on this subjects ..

[@dalerbsr.5061]

Great info, thanks again

[@MotionRC]

Our pleasure!

[@vlogbrunohenrique]

I just want to understand how the current increases with rotation while the voltage showed in the display drops a bit

[@limshanxian5546]

can i set the cut off voltage？ if yes, how?

[@davidcybul1259]

how can activate the timing funtion to fkly with it abd determine duratio of v¿battery whil ein flight }

[@PatJones82]

Good stuff! Thanks. 👍

[@terrytesdall7695]

Great video!! Thanks!!

[@federicoardizzone8509]

What motor you use ??? a 70 mm ? 80 ? 90 ?

[@bobbyenache7652]

Great knowledgeable video, where in the world did you come across that beautiful MIG 15, I must have 1.

[@garycopeland1798]

James, When I connected everything up my motor wouldn’t run. I have gone over the hook up several times but it still won’t run. I have the exact same unit you have on this video. Any help would be appreciated.

[@democracy2005]

can i also use this wattmeter for checking the ampload of airsoft aeg?

[@davidcybul1259]

i would love to put it in my l37 motion 737

[@txkflier]

The higher the C rating, the lower the internal resistance should be. Lower internal resistance means less voltage drop and less heat, but the battery will be larger and heavier due to the thicker components..

[@MChronicleSword]

Darn I shouldn't have went for the highest C ratings available in my new batteries then lol

[@txkflier]

@@MChronicleSword When you're pulling lots of amps in 100° Texas heat, you need the highest C rating you can get..

[@Denny_H]

Unfortunately, there is no standard for "C rating". The manufacturer can throw any number they want to on the battery, and many do. Rarely are they the rating they say they are, but higher is better if you can handle the additional weight and size.

[@txkflier]

@@Denny_H Yep, I’ve looked for the standard and couldn’t find it. I guess the designer calculates how many amps a battery can handle based on the design. There doesn’t appear to be a physical test that can be run. You’d have to start at a particular ambient temperature, airflow, etc. and stop when the temperature rises to a predetermined limit. Comparing the weight and physical size is about the only thing one can do. I’ve started using Liperior batteries because of the tests published on RCGroups. SMC batteries scored higher, but they’re more expensive..

[@ericklein5097]

Size does not necessarily correlate to IR. There are some tiny batteries with IR's below 1mΩ and batteries twice their size at 6mΩ

[@mahlonpeachey7667]

Can you use that same wattmeter for a Rc boat ??

[@ericklein5097]

sure why not? I wouldn't put it in the boat. Its not terribly heavy but it is a bit bulky

[@user-ff7py9mz9n]

Было очень интересно, только я ничего не понял.

[@Fullydownable]

may be model for 400 amp?

[@ericklein5097]

That would require cable in excess of 4/0 105 degree Celsius EPDM insulated welding cable (fine stranded). That stuff is rated for 320A. I would go no lower than 2/0 AWG EPDM Welding cable if I was just bursting 400A for seconds....like 5 seconds no more than 10-15. I don't know if anyone makes 200 degree Celsius Silicone insulated wire beyond 2 AWG but it would be VERY expensive. Probably $15 per foot for 4/0 AWG.EPDM is about $8 per foot for Royal Excellene but that is the top of the line welding cable.

[@ericklein5097]

And here we learn kiddos that C ratings are all absolute bullshit (99% of them, a select few brands are fairly realistic in their given C ratings) A 4ah pack rated at 40C is 160A yet we saw a 6S pack drop 5V at just under 100A. Dropping 0.8V per cell is what I (my opinion) would consider to be a good indicator that the max safe discharge rate has been reached. Other factors play into this like pack temp but voltage drop is pretty reliable. Taking a cell from 4.20 down to 3.40 is the most I've ever seen a lithium ion (sorry I'm not a Lipo guy) handle without the voltage becoming extremely unstable. I prefer 3.50V being the limit and consider 3.60V to be a very steady region that can be run for a little bit of time without heat becoming a serious concern. So that give us roughly an IR of 50 milliohms but that includes the meter and all the cable. I'd say drop at least 10 milliohms if not more off that figure. I suspect 6 milliohms per cell to be what they are capable of when new.