Alternator Question

[J persons]

I have a '14 SHO and keep it on a float charger when I don't plan on using it for a week or so. I also have a plug in digital volt meter. After starting, the voltage reads 14.5, then after about 30 minutes on the freeway it drops to 13.2 volts and stays there. Is this normal? Other Ford cars that I have used this meter on will stay at 14.5, regardless of how long the engine is running.

 

[SHOrod]

Yes, that sounds normal. Many modern vehicles have a "smart" charging system to help with fuel economy. The charging system only charges when necessary to reduce the load on the engine. Once your battery reaches the appropriate state of charge, the charging voltage is reduced. Your car also has a Battery Management System that should be reset when the battery is replaced as well.

-Rod

 

[kryptto]

Yes to add to @SHOrod to float charge connect to positive on battery, negative to a body part like strut nut. If you direct charge to both terminals your BMS will start to incorrectly read your batteries health and turn off the alternator and u won't get the proper charge time. Causing the battery to die quicker.

 

[J persons]

I've always connected the float charger neg to a bolt at the top of the strut tower area. The BMS was reset when Ford installed a new battery about 2 years ago.