# XVII.	Suggestion of use

* <mark style="color:red;">**We suggest you turn on your Nav XL while preparing your gear in order to make sure you get the GPS fix before taking-off.**</mark>
* Use the lanyard to <mark style="color:red;">**secure**</mark> your instrument while flying.
* Electromagnetic perturbations from VHF antennas can disturb GPS signal (Altitude/Speed/Glide ratio…)
* If the SYS'NAV is very hot and you fly in very cold air, fog can appear on the screen. It will dissipate within minutes.
* When plugging your Nav XL on a USB charger, it will charge even if it is turned off.
* The lifespan of your battery will depend on the conditions of use and its storage environment. Do not leave it without charge for a long time and do not leave your instrument in the trunk of your car in direct sunlight (Your wing won’t like it either).
* If the battery is too hot (instrument left in the sun in summer), the instrument will not allow you to start it. So wait for your Nav XL to cool down before trying again
* Charging can be done on any USB charger (computer, phone charger, solar panel…) provided that it respects the USB standards (avoid cheap chargers).

**Operating time and settings:**                                                                                                                                        The operating time very related to your settings. Here is a table allowing you to estimate the operating time of your instrument according to its settings:&#x20;

<figure><img src="/files/8PrPYvI1brAlyIPdqVyU" alt=""><figcaption></figcaption></figure>

Bluetooth activation has very little impact on the operating time.


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