I have 2002 7.3 power stroke ford. The battery on the passenger side always get a lot of acid build up. I clean it about once a month. It only corrodes on negative post and cable. I check voltage and it is always shows full charge. Can anyone yell me what can cause this?

THANKS MACK1.

The battery can be suphating around the post area. Have you tried using the treated fiber pads at the base of the posts? Other then that you may have to replace the battery.

Use a good terminal wire brush and clean. Then wash the affected area (terminals and posts and nearby) with baking soda and water.

Dry and look for any cracks around the terminal. Move the terminal to see if you expose any. If there are, replace battery.

Use the fiber pads.

You need an electrolyte (dirty water) is enough so also check for moisture sources.

In severe instances replace the cable.

Leaking case or caps. Be sure not to overfill each cell. Place a genuine copper penny or two in strategic areas to help prevent acid build-up on the terminals.

Check the regulated battery voltage, to ensure the alternator is not overcharging:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1973613

This link may also give you some ideas:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-4.html#post338216

I can find any cracks. Water level good. Only one post suphating on main battery. I use red protective on all post but I have not tried felt pads yet I will try that next. Alternator seems to be charging normal.