Corrosives and Aluminium

[paulharvey]

My battery mount tray is about 75% rusted away on my L285, partly do to weather, partly I'm sure from old battery in past life, or leaking battery hydrogen?oxygen?what ever gasses escape, so I used an old aluminium street sign to make a new one (not stolen, I got it legit, or mostly so)

So, I know aluminium will resist regular weather, but I also know some acids (muratic acid) attack it very aggressivly, so my question is, do battery gasses eat aluminium?

 

[hosspuller]

It'd not so much the O2 & H that attacks the metal, but the acid mist. Small particles of sulfuric acid that become airborne. Look closely at a pan of boiling water. You'll see little droplets as the bubbles burst. I think only a gelled battery doesn't have the mist.

 

[Baby Grand]

Assuming that you are bolting the aluminum to the steel structure of the frame in the presence of water and acid vapors, you've got the key ingredients for making a galvanic cell.
If the aluminum is well isolated, electrically, from the steel, then you may not have any problems with galvanic corrosion.

 

[paulharvey]

I justed used self tapping metal building screws. I did think about sandwiching a rubber mat (mud flap) betweem the steel and aluminium to reduce vibration on the battery, (which ive read kills them) but I didn't have one laying in my bone yard when I did this. I'm not out any money if it dissolves in a month, but I was hoping the aluminium would hold up for a few years.

 

[ETpilot]

I use a battery acid paint for the battery box. It works pretty well. On my Dodge truck the battery acid ate thru the box and on to the fender. It also ruined my cruise control servo which is below the battery box. I painted the whole area with this paint and it has worked well for me.

Using aluminum you have to use the right fasteners and avoid contact with other metals. If the contact areas get wet, a process of dissimilar metal electrolysis takes place and the aluminum can get eaten away. It is a common problem that is faced on aluminum airplanes.

Try the acid paint. Battery Box Paint

 

[orezok]

It'd not so much the O2 & H that attacks the metal, but the acid mist. Small particles of sulfuric acid that become airborne. Look closely at a pan of boiling water. You'll see little droplets as the bubbles burst. I think only a gelled battery doesn't have the mist.

You can eliminate the "acid mist" by pouring a ounce of common mineral oil into each cell. It floats on the surface and prevents the "mist" from off gassing. Back in the old days when railroad signals were battery powered, it was added to all the batteries. It's also used in the aviation, boating and RV circles.

Google Battery Oil for more info.

 

[Baby Grand]

You can eliminate the "acid mist" by pouring a ounce of common mineral oil into each cell. It floats on the surface and prevents the "mist" from off gassing. Back in the old days when railroad signals were battery powered, it was added to all the batteries. It's also used in the aviation, boating and RV circles.

Google Battery Oil for more info.

Great bit of information! Thanks.

 

[paulharvey]

Thanks for the information everyone. I guess when this fix fails I will go back with a 1/8th inch painted steel.

 

[Travelover]

My local recycler has all kinds of scrapped stainless steel for less than a buck a pound. If you have a friendly metal recycler, check 'em out.

 

[Don87]

Could just take a walk thru the local auto salvage yard. Every car/truck/bus in there has a battery tray in it.