# Battery Corrosion



## gnsjoy (Apr 29, 2014)

Six months ago I purchased a body off, fully restored 66 GTO. I noticed a white powdery substance on the exterior of the radiator next to the battery. After driving it a few times this spotty white powder began showing up on the underside of the hood above the battery. The battery died and I replaced it with a new maintenance free battery, placing anti-corrosion pads under the posts. This corrosion has gotten much worse, actually pitting the paint on the hood inner bracing. The voltage reading @ 2000 rpm is 13V, so it doesn't seem like it's over charging. The battery posts and cables are corrosion free. What might be causing this?


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## Lemans guy (Oct 14, 2014)

Gnsjoy, does sound like battery out gassing, try a little baking soda and water..does it dissolve the white powder? If so it likely is from battery acid.

13v @2000 rpm....but does that vary? A voltage regulator? They are about $21 dollars at the local auto parts store.

The alternator could still be overcharging depending it and you haven't caught it.

Radiators cyan corrode as well is yours OK leaking anything?

Sounds like the charging circuit or battery, make sure battery ground connection is good and tight, clean rust, if it bounces on and off may effect the charging circuit....


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## gnsjoy (Apr 29, 2014)

Voltage stays steady while I've watched the gage; ~12V at idle increasing to 13V with rpm. Baking soda does remove the white surface powder but you can feel pin size bubbles underneath the paint. Radiator is new, just a small spot on the side where it is scraped is where the powder and paint bubbles appear. Ground is solid; new cable and mount on head.


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## 666bbl (Apr 13, 2014)

Check all the body ground cables, little braided copper ones near the firewall and back of the cyl head. If they're dirty you want to clean em and apply some dielectric grease. If you don't have good grounds to the body weird sh.., uh, stuff can happen. The worst case would magnetize your shifter cable and lock it up (!). Also, you should be seeing voltage around 13.8 at 2000+ RPM, 12.6 or better at idle. The car/engine needs more voltage as load/RPM increases. All of it's worth a look, regulator, grounds, charging...

Quick edit: Put the + probe on the POS connection and the - on the top of the battery. Get a reading? Clean it real good. A battery can "leak" voltage across the top of the case. No reading, then it's OK.


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## eeyore (Oct 23, 2014)

Sounds like a coolant leak with worn out or incompatible coolants. Or GM Deathcool 
What color is the coolant?


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## Lemans guy (Oct 14, 2014)

All good suggestions, I have a tester called a MicroVat, you hook it too the battery and a cable on the alternator or ground wire, and it tests, with a microload, battery starter and alternator circuits.

Every service station has one VAT tester somtimes on a cart, but the hookup is easy, and it loads the circuit for a true test.

you might try that just get a test, bad component may show up. If that looks OK move over to the radiator as eeyore said


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## gnsjoy (Apr 29, 2014)

Lemans guy said:


> All good suggestions, I have a tester called a MicroVat, you hook it too the battery and a cable on the alternator or ground wire, and it tests, with a microload, battery starter and alternator circuits.
> 
> Every service station has one VAT tester somtimes on a cart, but the hookup is easy, and it loads the circuit for a true test.
> 
> you might try that just get a test, bad component may show up. If that looks OK move over to the radiator as eeyore said


Thanks, I will pursue these leads. It is electrical, definitely not a coolant problem.


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## gnsjoy (Apr 29, 2014)

666bbl said:


> Check all the body ground cables, little braided copper ones near the firewall and back of the cyl head. If they're dirty you want to clean em and apply some dielectric grease. If you don't have good grounds to the body weird sh.., uh, stuff can happen. The worst case would magnetize your shifter cable and lock it up (!). Also, you should be seeing voltage around 13.8 at 2000+ RPM, 12.6 or better at idle. The car/engine needs more voltage as load/RPM increases. All of it's worth a look, regulator, grounds, charging...
> 
> Quick edit: Put the + probe on the POS connection and the - on the top of the battery. Get a reading? Clean it real good. A battery can "leak" voltage across the top of the case. No reading, then it's OK.


I have verified there isn't any voltage leak across the top of the battery. Also verified there isn't any voltage draw with key off. All ground straps/cables and screws are new. However the frame has been powder coated so that may still be a possibility. I would think that the screws would cut into the paint and make a good ground. Also I think there would be other electrical problems if grounds were not good?
I've attached photos. This is the condition in three days after cleaning it up with soap and water. The car has been sitting idle and never been started during this time. You should be able to see that the paint is blistered from underneath.
I think the voltmeter I was using may not be accurate. Checked the battery voltage with another and got a reading of 12.8 v with the engine not running. I cannot run the engine right now as I've got a heater core coolant leak.


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## 666bbl (Apr 13, 2014)

I've found that bolts through paint offer very poor connections. All they have is the threads to make contact and threads are NOT solid connections. Is the alternator a newer 1 wire or the OE with a regulator? It's also possible for batteries to do funny things in big swings of weather conditions. 2 of my daily drivers would simply die if I didn't fire em up for 3-4 weeks. I too thought drain and disconnected it, but it was in fact the batteries (from O'Rielly). That's very odd that your paint is doing that. Last, and the most simple of guesses, all batteries emit some form of gas if even just sitting. Not a lot, not alarming, just vapors that "weep". It's possible that the paint under the hood is not able to hold up under those emissions. Do you know what was applied, or is it still the OEM finish, or...?


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## geeteeohguy (Feb 2, 2008)

If any of your grounding points are powdercoated, they are insulated. You'll need to wire wheel/sand the coating off to make a reliable connection at those points.


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## gnsjoy (Apr 29, 2014)

geeteeohguy said:


> If any of your grounding points are powdercoated, they are insulated. You'll need to wire wheel/sand the coating off to make a reliable connection at those points.


Will do, thanks!


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## Lemans guy (Oct 14, 2014)

Geeteeohguy is right on the contacts, I wire wheel them to bare metal and make strong connection at all grounds.

You changed batteries and it still happens. And it happens with the car not running, so it seems is not your charging system, alternator or voltage regulator. 

But looking at your Photos I am wondering if your hood is shorting on that positive post. if so you may get that minor electrical reaction even with the car off.

Lower the battery tray and leave it or move it off the tray and leave it, maybe you could remove the tray and just let it sit a few days and recheck.

or get a bendable camera in there with hood shut and make sure there is a gap. 

If it is touching it may be the source


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## allpawl66 (May 9, 2008)

Use a Optima battery no leaking acid , & a solid state volt. regulator . More accurate & stable charging . I have the regulator if needed . $35.00 shipped .


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