- 基本电池设置（默认值）：将原始测量电压与“空”和“满”电压之间的范围进行比较。 这样的估计较为粗略，因为测量的电压（及其相应的容量）将在负载下产生波动。
- 基于电流积分的电压估计：通过基于电流的已消耗电荷估计，对基于负载补偿电压的估计出的可用容量进行补充。 这样的容量估计相当于智能电池的容量估计。
The instructions below refer to battery 1 calibration parameters:
BAT1_*. Other batteries use the
xis the battery number. All battery calibration parameters are listed here.
This approach results in relatively coarse estimations due to fluctuations in the estimated charge as the measured voltage changes under load.
To configure the basic settings for battery 1:
- 打开 QGroundControl 并连接上飞机。
- 在上面的工具条中选择 齿轮 按钮，然后在左面的工具条中选择 电源 按钮。
You are presented with the basic settings that characterize the battery. 以下部分说明了为每个字段设置的值。
At time of writing QGroundControl only allows you to set values for battery 1 in this view. For vehicles with multiple batteries you'll need to directly set the parameters for battery 2 (
BAT2_*), as described in the following sections.
The voltage across a single galvanic battery cell is dependent on the chemical properties of the battery type. The most common drone battery type (Lithium-Polymer - LiPo) has a nominal cell voltage of 3.7V. In order to achieve higher voltages (which will more efficiently power a vehicle), multiple cells are connected in series. The battery voltage at the terminals is then a multiple of the cell voltage.
如果未提供电池数量，您可以通过将电池电压除以单个电池的标称电压来计算它。 下表显示了LiPo电池的电压 - 电池关系：
- 1S - 3.7V
- 2S - 7.4V
- 3S - 11.1V
- 4S - 14.8V
- 5S - 18.5V
- 6S - 22.2V
The voltage of a full battery may drop a small amount over time after charging. Setting a slightly-lower than maximum value compensates for this drop.
This sets the nominal minimum safe voltage of each cell (use below this voltage may damage the battery).
There is no single value at which a battery is said to be empty. If you choose a value that is too low the battery may be damaged due to deep discharge (and/or the vehicle may crash). If you choose a value that is too high you may unnecessarily curtail your flight.
A rule of thumb for LiPo batteries:
- 负载下3.5 V（飞行时）接近真实最小值。 在这个电压下, 你应该立即降落。
Below the conservative range, the sooner you recharge the battery the better - it will last longer and lose capacity slower.
If you have a vehicle that measures voltage through a power module and the ADC of the flight controller then you should check and calibrate the measurements once per board. To calibrate you'll need a multimeter.
The easiest way to calibrate the divider is by using QGroundControl and following the step-by-step guide on Setup > Power Setup (QGroundControl User Guide).
This setting is not needed if you are using the basic configuration (without load compensation etc.)
The easiest way to calibrate the dividers is by using QGroundControl and following the step-by-step guide on Setup > Power Setup (QGroundControl User Guide).
With well configured load compensation the voltage used for battery capacity estimation is much more stable, varying far less when flying up and down.
Load compensation attempts to counteract the fluctuation in measured voltage/estimated capacity under load that occur when using the basic configuration. This works by estimating what the voltage would be for the unloaded battery, and using that voltage (instead of the measured voltage) for estimating the remaining capacity.
To use the load compensation you will still need to set the basic configuration. The Empty Voltage (BAT_V_EMPTY) should be set higher (than without compensation) because the compensated voltage gets used for the estimation (typically set a bit below the expected rest cell voltage when empty after use).
PX4 supports two load compensation methods, which are enabled by setting either of the two parameters below:
- BAT1_R_INTERNAL - Current-based Load Compensation (recommended).
- BAT1_V_LOAD_DROP - Thrust-based Load Compensation.
This load compensation method relies on current measurement to determine load. It is far more accurate than Thrust-based Load Compensation but requires that you have a current sensor.
To enable this feature:
- Set the parameter BAT1_R_INTERNAL to the internal resistance of battery 1 (and repeat for other batteries). > Tip There are LiPo chargers out there which can measure the internal resistance of your battery. A typical value is 5mΩ per cell but this can vary with discharge current rating, age and health of the cells.
- You should also calibrate the Amps per volt divider in the basic settings screen.
This load compensation method estimates the load based on the total thrust that gets commanded to the motors.
This method is not particularly accurate because there's a delay between thrust command and current, and because the thrust in not linearly proportional to the current. Use Current-based Load Compensation instead if your vehicle has a current sensor.
To enable this feature:
- Set the parameter BAT1_V_LOAD_DROP to how much voltage drop a cell shows under the load of full throttle.
This is the most accurate way to measure relative battery consumption. If set up correctly with a healthy and fresh charged battery on every boot, then the estimation quality will be comparable to that from a smart battery (and theoretically allow for accurate remaining flight time estimation).
This method evaluates the remaining battery capacity by fusing the voltage-based estimate for the available capacity with a current-based estimate of the charge that has been consumed. It requires hardware that can accurately measure current.
To enable this feature:
First set up accurate voltage estimation using current-based load compensation.
Including calibrating the Amps per volt divider setting.
Set the parameter BAT1_CAPACITY to around 90% of the advertised battery capacity (usually printed on the battery label).
Do not set this value too high as this may result in a poor estimation or sudden drops in estimated capacity.
The estimate of the charge that has been consumed over time is produced by mathematically integrating the measured current (this approach provides very accurate energy consumption estimates).
At system startup PX4 first uses a voltage-based estimate to determine the initial battery charge. This estimate is then fused with the value from current integration to provide a combined better estimate. The relative value placed on each estimate in the fused result depends on the battery state. The emptier the battery gets, the more of the voltage based estimate gets fused in. This prevents deep discharge (e.g. because it was configured with the wrong capacity or the start value was wrong).
If you always start with a healthy full battery, this approach is similar to that used by a smart battery.
Current integration cannot be used on its own (without voltage-based estimation) because it has no way to determine the initial capacity. Voltage-estimation allows you to estimate the initial capacity and provides ongoing feedback of possible errors (e.g. if the battery is faulty, or if there is a mismatch between capacity calculated using different methods).
Multiple battery support was added after PX4 v1.10, resulting in the creation of new parameters with prefix
BAT1_ corresponding to all the old parameters with prefix
BAT_. Changes to
BAT1_ are currently synchronised:
- If either the old or new parameters is changed, the value is copied into the other parameter (they are kept in sync in both directions).
- If the old/new parameters are different at boot, then the value of the old
BAT_parameter is copied into the new