There are two charger options for Baofeng radios: one that is connected directly to power mains and has integral power supply and one with external power supply. Some are designed to run on 12 Volts but some, like my Baoeng UV B5, use 10 Volts power supply.
My idea was to be able to use this to charge radio in various power conditions including in my car and this voltage was a problem. I noticed comments that charger should not be connected to higher voltage than 10 Volts but nevertheless I decided to risk and try connecting charger to 12V power source. It did not die. Actually it worked just fine.
I took it to the car and it worked the same on 13.8V coming from car battery. Actually, it worked until I started motor. When motor is running, car power system runs on 14.4V, and charger decides that is too much and shuts down. It does not die, just shuts down. When connected to regular power again it works fine.
The simplest method to handle this was to try to add rectifying diode on series with power supply. It should provide 0.7V voltage drop hopefully enough for charger to work. It did the trick, indeed. After modification, charger runs fine when car engine is running.
Good thing is that charger still works fine with original power supply. So at the end it could not be better.
You can see in photo above how I cut power line on printed circuit and added 1N4001 diode to the circuit. This modification should work with all similar chargers.