Quote Originally Posted by kelvo View Post
Yes, but you need to make sure you get a decent one so you don't drop the voltage when actually charging it. A solar panel one would probably be a good option.
A diode will always drop 0.6V that is how they work. There is a type of Diode that only drops 0.2V but i think it's only available for circuit boards and not in a high enough current capacity for this application.

To drop 0.6V is not necessarily a bad thing if you are charging at 14.5V and the battery you are charging is a sealed battery. It will be fine, it does not need to be charged hard.