Umm, i want to know , can i charge dji spark battery attached to drone overnight?

Im not sure about the older Mavic  versions, but I think you can as the batteries have smart tech.

Hi there. Thank you for reaching out. Normally, the DJI Spark battery can be fully charged for around 80 minutes with the original USB charger. We highly recommend not leaving the battery on the charger overnight to avoid any unknown issues. Should you have other inquiries, please don't hesitate to reach us. Thank you

Hi,

Yes you can do that. I find that actually a very nice feature of the Spark, useful when you are on a trip with your drone and want to recharge it on your vehicle.
You need a USB charger that is capable of delivering 2 amps or more, though.

HTH,
Wolferl

Leaving your DJI Spark battery attached to the drone while charging overnight is not recommended.
While the DJI Spark has built-in safety features to prevent overcharging and overheating, it is still a good practice to disconnect the battery from the drone after charging it fully.

Overcharging your battery can reduce its lifespan, and in extreme cases, it can even cause the battery to swell or catch fire. To ensure the longevity of your Spark battery, it is best to remove it from the drone and store it separately when not in use. ^^