Battery Information

The high voltage batteries used in the Ranger Pro should be charged on LiHV, rather than LiPo, which is the default setting on the SKYRC dual battery charger that is packaged with WISPR drones. In the event of a power outage in a location where your charger was plugged in, be sure to change your charger back to LiHV- as the charger will reset to LiPo when disconnected from power.

How to set the battery charger to LiHV for charging high voltage batteries, and the battery charging process:

  • Hold the up and down arrows on the charger until the setting is changes to LiHV instead of LiPo.

  • Plug the battery’s XT90 connector into the XT90 port on the charger (yellow plug).

  • Plug the balance port on the battery into the balance port connected to the battery charger (white plug).

  • Change charging to 20A, if the charger is not already set to this value.

  • Press and hold the start button until the charger beeps three times. You should see a warning on the screen about charging high voltage batteries.

  • Soft press start one more time to begin charging.

You should see the voltage increasing, as the battery is now charging. If you would like to change a setting, such as balanced charge to fast charge, simply press the start button once to stop charging. Then soft press start again and the selected option will blink letting you know it is ready to be changed. Change the setting using the up or down arrows. Each press of the start button will select the next item on the screen that can be adjusted. Once you have each settings configured the way you would like, press start again to lock the adjustments in.

To see an example of how to charge your batteries correctly, and how to configure your charger settings properly, please watch the video below.

Charging Your Batteries with the Ranger Pro

Charging a LiHV battery on LiPo setting will likely not cause a fire but will not allow a full charge, and can damage the battery. Charging a LiPo battery on LiHV settings can cause a fire. Please be aware of this.

How to determine if a battery is fully charged:

The WISPR battery will charge to 26.11 volts. Even once the battery voltage reaches 26.11 on the charger screen, that does not mean it is fully charged. You should wait until the charger sounds to indicate the battery is finished and the screen reads “END: FINISH” to get the most out of the battery. You will also recieve multiple beeps once a battery is completly charged.

Battery Charging Modes:

  • Fast Charge - This mode directs the charger to only complete the first charging phase, constant current (CC) charging. The charger applies a high enough voltage to cause current to flow into the battery, up to the max current you've set. This will mostly charge the battery, but there will still be some unused capacity with this mode.

  • Balanced Charge - For maximum health, you should always balance charge your batteries. This is also why your battery has a second plug. This second plug is called the “balance plug” and is used by your charger to individually monitor and balance charge each cell.

  • Storage Charge - This option should be used if you are not planning on using your battery for an extended period of time (24 Hours or longer). You should never store a fully-charged LiHV battery. Instead, it should be set to the storage charge setting and the voltage decreased to “storage voltage”, which is 3.8 to 3.85 volts per cell.

If upon plugging a battery in, the battery immediately beeps with an error preventing charge:

  • Check that the balancer plug (white plastic plug on the battery) and the XT90 plug are properly plugged into the respective ports and wires coming from the charger. Wires on both ports (balancer and XT90) should be plugged in tightly.

  • Verify that you have the correct charging mode set on the charger.

    • If these options are not the issue, use the charger to make sure all cells are balanced. You can check the cells by pressing the stop button once, the start button once, and then the up arrow once. If you see a damaged cell, (one reading completely different from the others) replace the battery immediately.

Flying with damaged batteries:

NEVER fly with a damaged battery, even if it is minimal damage. This can cause erratic behavior or accelerated battery depletion, which can result in a crash. Replace the battery and safely dispose of the damaged battery.

Proper procedure for inserting the battery into the battery tray:

  • The positive and negative wires (red and black wires attached to the XT90 battery connector) should be on the right side when inserting into the battery tray.

  • Additionally, the battery strap should be:

    • Looped around the left standoff of the entrance to the battery tray. The velcro side should be facing outwards.

    • Pulled from left to the right, threaded between the positive and negative wires.

    • Around the right side of the battery, in between the battery and the standoff.

    • Run back through the battery wires, pulled tight, and pressed firmly against the soft side of the velcro to secure the battery in the tray.

    • Wedge the remaining connector in between the battery and the strap.

    • Ensure that the loop around the left standoff is positioned to rest in the center of the standoff, so that the strap stays in place for the duration of the flight. The strap should go evenly across and be firmly pressed against the battery.

Proper procedure for powering the drone:

Be sure when powering the drone that the battery plug is flush with the port and inserted in one swift, smooth motion. Inadequate alignment or lingering for too long when making partial contact may result in an electrical arc, causing the wires to generate excessive heat, consequently leading to battery swelling and malfunction. Sometimes it is helpful to grasp an arm of the drone with your other hand to keep the drone stationary. This will prevent the drone from tilting backwards if the plug fights tightly into the port.



Hot-swapping a battery allows you to swap batteries in your drone while the drone is still powered on. This allows you to extend flight time without having to power down the drone. This also allows you to continue your mission from the previous waypoint without powering down the drone.

To hot-swap a battery, follow these steps:

  • Ensure that your drone is equipped with the hot-swap cable.

  • Fly the drone until the battery reaches the low battery failsafe and the RTL sequence is initiated.

  • Ensure that the drone lands in a suitable location for a safe touchdown, which should be level and free of debris.

  • Once landed, on the right of the smart controller screen you will see three options appear: “Keep mission”, “Resume from waypoint X” and “Delete mission”. Select “Resume from waypoint X” to have the drone continue from the last waypoint you reached in the mission, after the hot-swap and takeoff are complete.

  • Plug the charged battery into the free XT90 port of the hot-swap cable and disconnect the used battery from the hot-swap cable immediately after the fully charged battery is plugged in. Next, slide the new battery into the battery tray after the depleted battery has been removed. Make sure that the new battery is properly secured in the battery tray.

  • Once the charged battery connected and the used battery is disconnected from the hot-swap cable, you will see the percentage at the top of the Fly View bar raise to the percentage of the charged battery.

  • Once the charged battery is in use and the percentage is displaying the updated value, you may launch to continue your mission. The mission will start from the previous waypoint and continue with a now new fully charged battery without ever powering down the drone.


WISPR hot-swap Cable

Further hot-swap instructional video can be found here:

It's important to note that to use only batteries from WISPR, as this can help reduce the risk of accidents or malfunctions. Be sure to follow all safety guidelines and precautions when hot-swapping a battery in a drone.