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title = "INAV tuning tips"
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Here are some general INAV tuning tips and things I've learned throughout my builds. Keep in mind that *these only apply to wings* (and maybe planes), not quads:

* There's a known problem with horizon drift. To ameliorate it, use `set imu_acc_ignore_rate = 10`. Setting this low is a good idea, but if it's set too low then the accelerometer will effectively be ignored and the horizon will eventually drift. To reduce the accelerometer's influence, you can also reduce `imu_dcm_ki`/`imu_dcm_kp`.
* To make turns in automatic modes smoother, use `set nav_fw_control_smoothness = 8`.
* Pawel says that the idea of the software LPF is to replace the hardware LPF. Leave the hardware LPF set to 256 Hz and set the software LPF to 20-30 Hz, with a looptime of 1k.


## Battery monitoring

To monitor how much battery you have left in flight, voltage isn't a good indication because it can sag a lot. mAh is also not a good indication, because it doesn't decrease linearly with voltage. Energy is a better way, using the "Wh drawn" INAV OSD item. In addition, INAV has heat loss compensation for the energy meter, which gives you a more accurate reading.

To calculate the Wh a battery can give, the best way is to charge or discharge it and see how many Wh were spent, if your charger shows you. Another way is to get a rough estimate using the formula `no_cells * 3.7 * Ah`. So, for a 1800 4S battery, the maximum Watt-hours are `4 * 3.7 * 1.8 = 26.64 Wh`. **You should not discharge more than 80% of that value.**

For a 4S battery, I go with a rule of thumb: The maximum Wh is `mAh / 100`, so for a 5000 mAh battery I'll start to land after 50 Wh consumed, which is around 70% of the battery consumed and gives a nice margin for error.

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*Last updated on December 20, 2020.*