# RC Electric Calculator App for Android

RC Electric Calculator App for Android - new version 2.1 out now!

It's basically an 8-in-1 calculator for electric powered model airplanes, helicopters, multicopters, cars, trucks and buggy's, if fact anything that uses rechargeable* batteries. (*As long as the voltage is known then any rechargeable battery including LiPo, LiFe, NiCd and NiMh batteries can be used for some calculations). US imperial units and metric units are also catered for!

One of the units used for the calculations in the app is the mAh (mill-amp-hours). All batteries have a mAh or Ah rating, this is the capacity of the battery or how much energy is stored. After you've recharged the battery your digital charger will show you how many mAh has been put back into the pack i.e. how much was used. This number is used to calculate a number of things in the app, like expected flight time using 80% of the pack or the average current used during the flight or run.

A use for this app is to calculate the average current draw of a multicopter in a hover and then from this calculate the expected flight time. (I flew with ArduPlane for 29 minutes from 2300mAh and the app calculated the average current draw as 4.6 Amps, or 1.6C and 77% of the 3000mAh pack!)

RC E-calc Pro - only \$1.99

As from v2.0 all the calculations are made "on-the-fly" so no buttons need to be tapped, just input your values and the calculations will be made when enough data is available.

The images should explain how it all works but feel free to ask any questions.

Use RC E-Calc Pro to calculate the following:
- Average Current Used by the aircraft during a flight/run.
- Average Discharge Rate (C-rate) of the LiPo battery during a flight.
- Expected Flight Time using 100% capacity of a battery.
- Expected Flight Time using 80% capacity of a battery.
- Realistic Flight Time using 80% capacity of a battery and 70% average throttle.
- Power in Watts from Volts & Amps.
- Volts from Power & Amps.
- Current in Amps from Power & Volts.
- Static thrust of a propeller in pounds or kilograms.
- Power to Weight Ratio in Watts-per-pound or Watts-per-100gram.

Examples:

a) Fly (or drive) for 11 minutes and 20 seconds, then recharge your 2200mAh LiPo, when finished your charger states that 1720mAh was returned to the battery. This app will then calculate that the average current draw for the flight was 9.11 amps, the discharge rate was 4.1C and you used 78% of the rated capacity of the battery. (Img #1)

b) How long can you fly your plane safely? It is recommended to fly using only 80% of the capacity of LiPo batteries to maximize their longevity so using the 9.11A average from the example above, the full throttle current draw (you will need to measure this) is 16A, input 2200mAh and 16A into the app and it'll calculate that you should be able to fly (at FULL throttle) for 6 minutes 36 seconds until the battery is 80% depleted or for 8 minutes 15 seconds (also at FULL throttle) until it is 100% depleted. (Img #2)

A "Realistic" flight time for a plane is also calculated which works out to be 11 minutes and 47 seconds using 80% capacity and 70% average throttle, very close to the actual flight time in the first example.

For helicopters and multicopters the flight time is very dependant on what style of flight, but you can use this calulator's section to calculate the expected flight time in a hover.

Disclaimer: The formulas used in these calculations come from various internet sources, with some variations added from my own experience. Your results may vary! While a lot of effort was put into ensuring accuracy, this app is not intended to be professionally accurate.

thanks,
Graham

P.S. Sorry I don't have an iphone so this is not available in the App Store

Views: 2017

Comment by Gagarien on September 15, 2012 at 8:25am

Very nice Graham looks good

Comment by Louis on December 20, 2012 at 7:05am

I have see this app at work, and it is great.

But I have an Iphone, so I will depend on you to calculate for me, LOL !!

Comment by Chris Nelson on December 20, 2012 at 10:57am

Just bought the app. Nice, easy to read. Would like to see: model flight log with photo ID and QR support, vibration tools geared more to our hobby (A-B comparison), and have it fly my quad for me while I snooze. OK, just kidding on that last one. Thanks for putting this together.

Moderator
Comment by Graham Dyer on December 20, 2012 at 12:45pm

Thanks Chris, appreciate the comments. I use and can recommend T3chDad's RC flight log (https://play.google.com/store/apps/details?id=com.FlightLog&fea...) for flight logging with photo plane ID.

Comment by Chris Nelson on December 20, 2012 at 3:16pm

I'll check out that app. Here's another one for my wishlist: A model timer. Tell it what you are flying and it automatically will report on battery usage, perhaps using voice cues, based on the numbers the calculator comes up with. Ties into the flight logger idea.

Comment by Earl on December 20, 2012 at 7:31pm

bought it. works good

earl

Moderator
Comment by Graham Dyer on December 20, 2012 at 11:35pm

Chris, this one has a timer with vibration alerts and a logger: https://play.google.com/store/apps/details?id=com.gid.rcflightlogge...

Comment by Chris Nelson on December 21, 2012 at 11:26am

T3chdad's app is pretty sweet. No QR support. Would simplify the flight logging by simply scanning the plane and battery and then a timer automatically starts when you activate it. I guess in this case, I'm in favor of all in one type apps. Thanks again for the awesome app to determine flight times, Graham!

Moderator
Comment by Graham Dyer on January 29, 2013 at 8:01am

New version is finally up on the Play Store. (link)
New features:

• Unit converter (RC specific)
Torque
Mass
length
• Numerous layout and UI fixes

One of the new things is working out your likely run/flight time from how much mAh is returned to the battery after a flight. The expected run time is now calculated for you from the average current used during the last flight (at the bottom of this pic):

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