4020 24V system change to 12 V

The problem with 24 volt is you have to keep it balanced or add 12 volt resistors. Thus if you hook up anything that requires 12 volt electrical power, you need to make sure you draw evenly off both batteries.

Some day I plan to pull a round baler with my 4020, and many of those have electrical controls...I did not want to mess with the problems (have minor in electrical engineering, so not like I'm not capable).

If everything is in proper repair, and have quality components, either setup should work fine.

That being said, I have never converted my own 24 Volt 4020 to 12 Volts and do not intend to. If you do the repairs and maintenance needed to get your 24 Volt system in shape, it should work for many years.

Some of the 12 Volt conversions never did spin the engine over as fast as the old 24 Volt systems.

I understand there are gear-reduction starters available for certain newer Deeres that fit back to the 4020's and work well for this application. If I were to convert, I'd look into getting one of those starters. Check the archives, information has been posted here several times on which newer gear reduction starters to use.

The proper operation of the fuel gauge can be an issue with a 12 Volt negative ground conversion, as the fuel gauge in a 24 Volt 4020 operates at 12 Volts POSITIVE ground. Getting it to work properly will involve getting a sender and gauge for a newer (factory 12 Volt) 4020.