hi guys, this time im back because i detect some issue refer to battery monitor system in last mission planner.
On battery tab in APM setup screen its impossible write manualy any values..
and the battery voltage indicated is for example : 10.66 v but if i test the battery with my manual voltimeter it show me 11.35 v !!! why is that diference in mesurement?
my settings are: Monitor 1:3 Cell Capacity 6000
(I have a lipo battery Dualsky 3 cells 11.1v, 6000 capacity.
Faced the same issue and I changed the value of the Voltage Divide Ratio (Rescaled it).
//#define VOLT_DIV_RATIO 12.6
#define VOLT_DIV_RATIO 14.364 //scaling 1.14 times
# define BATTERY_EVENT ENABLED
# define LOW_VOLTAGE 10.5
# define CURR_AMP_PER_VOLT 27.32
I am using AttoPilot voltage and current sensor. Now I am approximately measuring the exact values
I am using AttoPIlot sensor. Had to rescale the voltage divider ratio to get the right values too.
The difference in measurements may be explained as a voltage drop, because when you define voltage using multimeter - it doesn't cause big current flow (and a voltage drop as a consequence).
Hey guys, i've been using the latest trunk as Michael said for the advanced input stuff in MissionPlanner, with the attopilot voltage/current sensor
Couple questions, first, i'm not using a voltage divider on my APM, just using the attopilots, i'm having to set my voltage divider ratio to 17.44 to get accurate reading on a 3s battery!
I have a feeling thats too high and maybe APM isnt handling the sensor correctly?
Also from the data sheet, the amps-per-volt that is set default in the APM code seems wrong too
50V/180A = 63.69mV / Volt 18.30mV / Amp
50V/90A = 63.69mV / Volt 36.60mV / Amp
13.6V/45A = 242.3mV / Volt 73.20mV / Amp
for the 50v/90a sensor that would be 36.60mV/Amp, but APM default is 27.32? really confused as to why. Which part of code is responsible for directly reading those pins? I'm wondering if maybe the code could be better handled for that setup, imo case should simply be for battery monitor option 4 (using the volt/current sensor externally) expect no volt divider resistor on APM side, and in Mission Planner have the user input volts/volt and volts/amp, instead of voltage divider value (its confusing and misleading with this setup, and leads to unnecessarily arbitrary values)
Ahh i see the 27.32 is the inverse of .0366V/1A, however the 17.44 volt ratio i'm having to input to get correct voltage reading is still bothering me
I think i've found another issue in that the Attopilot sensor is made for 3.3v ADC and the ardupilot code references 5v (actually 4.68v in code) ADC, does that matter at all? I'm not overly versed in arduino and/or analog inputs but that seems to be a discrepancy