ISDT Air8 500W 20A 1-8S DC Smart Charger

This lives in my FPV backpack, perfect when travelling as it's small, but still charges really fast.

Only downside is it gets upset when input voltage is less than 10V, which will happen on a lot of 12V DC sources under load.

Using a higher voltage source, or a more stable 12V source is fine

I have improved the situation with a cigarette lighter adapter that steps up the voltage to 19.5V before feeding into the charger.