Aluminum mount corrorsion issues

[Doug1]

I need an electrical guru to help me understand the chemical reaction happening here. This aluminum bracket has corroded in less than a week and with the power cut most of the time using the remote battery shutoff solenoid that is mounted to this very bracket. The other solenoid is a high amp alternator shutdown. Both made by Painless Performance.


I did have to put a 300 amp charger/starter on it for a little while last week when I was working out the ignition issues but I don't know if that affected this in any way. Regardless, I need to get it figured out sooner than later! I'm going to isolate the aluminum from the steel below but am not sure that would cause this much corrosion in such a short period of time.



















I need an electrical expert to chime in on this! Is this simply because I didn't isolate the aluminum from the steel frame?

[astroracer]

Are you using the aluminum bracket to ground your solenoids? There has to be a current of some kind running thru the bracket for it corrode that quickly. Isolate the bracket from all electrical sources.
Mark

[Doug1]

Not using it for any grounds. That's why its confusing. I'm thinking the remote power cutoff solenoid which activates with a switch to ground may be the culprit.

[krom]

you sure none of those relays ground through their mounting bracket? If they are switched by applying power, then they must ground through their mount

[andrewb70]

you sure none of those relays ground through their mounting bracket? If they are switched by applying power, then they must ground through their mount

^^^^This....I am quite certain all of those big Ford style relays ground through the built in mounts.

Andrew

[NOT A TA]

My guess........Looks to me like you boiled the battery charging it (Odysseys require certain charging techniques) and the ( heavier than air) gas emitted caused aluminum sulfate. The gas being more concentrated in the corner areas where it didn't dissipate as quickly as more open areas. Notice the distinct line about an inch high where the corrosion stops on the vertical bracket in the corner. That would be how high the layer of concentrated gas was in the corner where it didn't dissipate as quickly. The aluminum being used as a ground path may have sped up the corrosion process which is why it looks worse than the base of the battery "box" since the battery tray isn't an electrical path.