Battery monitor

[lucaszanella]

Can I make my own battery monitor with resistors? Multiwii will read this? Can I see the battery level in the GUI?
In wich pin I have to plug it?
The GUI displays the altitude? Wich measure system? Foots?
yhanks

[PatrikE]

For a 3s Cell use
R1=33k and R2=51k
Connect to A3 pin on PromMini
Or A0 On a Mega board.

We are using Metric system in the project.
The GUI displays the altitude in meters.

[lucaszanella]

33k to ground and 55k to vcc? 10kohm from GND to analog input? The GUI displays the battery level?

Thanks

[Pyrofer]

I used a 47k and 30.6k (its all I had), but that seems to work fine.
How do I calibrate the voltage readings with the actual battery voltage levels?

I put a fully charged 11.1v lipo on that said it had reached 12.5v and the reading from the control board was only 11.4v ?

[Hamburger]

1 use voltmeter and measure battery voltage v1
2 attach bat to mwii and get volt reading v2
3 set vbatscale to old.vbatscale * v1 / v2
4 set levels to 10* warning voltage
5 fly and repeat 1 to 3 for finetuning

[Pyrofer]

Thanks but I think there is something wrong with your math.
Original vbatscale was 131
Battery with voltmeter was 12.46 and the GUI said 11.6.
131 * 12.46 / 11.6 = 140 (which pushed the voltage reading further off.
I actually needed a vbatscale value of 122 for my resistor values and the real voltage closely matches the GUI now.
This should have been old.vbatscale * v2 / v1 = new.vbatscale,

Not complaining, I appreciate the help but thought I would clarify this in case anybody else comes accros this thread.

Anyway, solved now.