white junk on batteries and alternators

[JHZR2]

Hello,

On our 94 previa (219k), the original battery (panasonic) lasted over 10 years without issue. It was replaced with an interstate and then again, due to a loss of charge.

The alternator seems to work fine. 14.3V is the output at idle under 50F or so temperatures.

The only battery that has not had significant white residue and powder around the terminals, at the clamp-down points, etc., was the original. I noticed what looked like white powder that looks like it has "flowed" down the positive wire in liquid state then dried up and left streaks.

So, I have to wonder if there are circumstances where the alternator intermittently goes too high in voltage and causes the battery to get hot and start to release. This is being watched on a 100 mile drive as I type this.

Interstate batteries seem to be some of the best out there. Obviously there is an issue that causes this junk to come out of the battery. Some cars seem to get this, others never do... My truck definitely puts out 14.4V or so under most conditions, and never a sign of any powder or residue.

So, what REALLY causes these white powder residues to form? Does replacement of the alternator tend to help? Can the regulator create issues that are unseen due to easy/fine starting power from the battery and "good" voltage levels?

Thanks in advance!

 

[brianl703]

I believe it's caused by a broken seal between the battery post and the top of the battery, perhaps due to excessive lateral force applied to the battery post.

 

[JHZR2]

What about at the clamp down/over points? No post and no post anywhere nearby... But excessive amounts of this stuff.

I suppose you could say excessive clampdown forces breaking the seal there too... possible?

If there is no known data to suggest that an improperly performing alternator can have something to do with this, great... I'd just hate to replace another battery (cant imagine that both posts and casings have been damaged twice), then have an alternator issue that causes premature failure of yet anther battery...

Thanks for the info!

 

[Mike_dup1]

This is common, its air attacking the lead in the terminals.

Disconnect the terminals, negative 1st then positive and clean them (battery terminals and cables connections) with baking soda and water, wire brush everything clean, use 100 grit sandpaper to clean up the connections for good contact. Reconnect the terminals in reverse order and coat the exterior surfaces with grease to keep the air out. They say Coke Cola works also but I never tried it.

 

[Chris142]

Interstate and Exide both have this problem alot.

 

[spyghost]

i put regular multipurpose grease before re-installting those terminals.

 

[ZZman]

The white powdery substance is sulfuric acid and hydrogen crystals from the escaping hydrogen battery gases and liquid (the batteries have vents that allow the gases to escape.)

Vaseline works good on the cables after you clean them.

 

[johnd]

I had a guy tell me long ago, just drip the oil off the dipstick on the positive terminal every time you check the oil. This actually works and will keep the terminal from the chemical reaction. and yes, Coke works just as well as baking soda but I prefer it applied internally (in me) with a little whiskey added and use the baking soda on the battery.

 

[eljefino]

You're probably going to want to check inside that battery cable insulation when you get a good moment to check things over. Sometimes the acid will invisibly eat up the copper inside. Happens a lot on GM side terminals for some reason... better gravity perhaps.

An overcharge should burp out the low-maintenance caps and lead to low water. I had an interstate in my mazda that worked as perfectly as one could hope: only time I ever cleaned the battery terminals it was to get a dark grey/ black oxidation off. There was no acid flaky involved.

 

[MinivanMauler]

That white powder on the terminals is usually lead(II) sulfate:

Pb + H2SO4 ---> PbSO4 + H2

It is not particularly water-soluble. You pretty much have to scrub it off with a wire brush. If you go this route, wear a mask, fer cryin' out loud:

http://www.chem.tamu.edu/class/majors/msdsfiles/msdsleadsulfate.htm

 

[swalve]

Originally Posted By: eljefino
You're probably going to want to check inside that battery cable insulation when you get a good moment to check things over. Sometimes the acid will invisibly eat up the copper inside. Happens a lot on GM side terminals for some reason... better gravity perhaps.


I can report that this happened to me- it didn't eat the cables, but was probably going to if I didn't catch it. I took apart the ring end, screw and cover, cleaned them up, and doused them liberally with dielectric grease. So far, so good.

Yeah, it's a chemical reaction between sulfuric acid (probably in vapor form) and the lead on the terminals. Coat the lead with something and the problem goes away.

 

[kgb007stb]

We seem to have three converging problems at once.

First, let’s start with the alternator, voltage at idle tells us nothing about the state of the health of the alternator unless it is tested under a constant load. Why do we do this? Alternators are comprised of three independent alternating circuits that overlap each other otherwise they could not push alternating current into your battery. Most people do not realize that all three independent circuits have to be functional in order for the alternator to give its specified charging current. Due to heat cycling, over time either the independent windings go bad or the diodes which convert the AC current to DC current go bad causing the alternator to fail. It is hard to detect a failed alternator as it can function perfectly fine on either one or two of its remaining circuits producing 1/3 or 2/3 of the rated current.

Second, detecting white powder on the battery, is simply nothing more than electrolyte mist exiting the battery settling on top of the battery terminals. Electrolyte will then react with both the positive and negative terminals just as it would inside the battery, what you see is the final product after the electrolyte reacted with the terminals to produce electric energy. General cause of battery misting is overcharging, as a battery reaches near charged state the regulator backs off the charging current to the battery. If it fails to do so, battery is being overcharged. An overcharged battery reacts naturally to overcharging by shedding excess energy through heat dissipation (IsquareR loss, hence why batteries get warm during rapid charging/discharging) and the breaking of electrolyte into H and O gasses. As these gasses boil to the surface, they pick up some electrolyte and launch it into a fine mist within a cell. Further gassing produces positive pressure within a cell pushing the electrolyte mist out of the battery. Once outside, the electrolyte mist has no energy to rise, thus it begins to fall back to the battery where it settles on top of the battery cover and its terminals. Excessive overcharging can be usually confirmed by this condition on top of the battery as well as an excessive loss of electrolyte inside a new or fresh battery. Reason why the old battery did not exhibit this condition is because after 10 years it probably was low on electrolyte, thus with the level low the mist had to cover a greater distance to escape from a cell. On a new battery, electrolyte is much higher at its appropriate level thus it needs much less energy to escape the cell.

Third, diodes have a healthy ripple effect caused by the alternating current of the alternator. Most diodes will have a small ripple effect which is being absorbed by the battery. Hence the term never to run your car without a battery, high voltage and ripple would kill the onboard electronics. As diodes age and right before they go bad, they tend to filter less of this ripple effect causing more of a jolt/shock to the battery. If not treated in a timely matter, ripple will kill the battery in due time; one reason why those who fail to replace faulty charging systems usually end up replacing the battery as well. Ripple requires more sensitive instruments to be measured properly, but any decent alternator shop will run the alternator through these diagnostics to determine whether a rebuild/replacement is necessary.

 

[brianl703]

Quote:
It is hard to detect a failed alternator as it can function perfectly fine on either one or two of its remaining circuits producing 1/3 or 2/3 of the rated current.


This would show up as lower than normal output voltage, especially at idle. I was able to detect when the alternator in my Mustang had a partial diode failure from the instrument cluster voltage gauge, which is hardly a precision instrument.

Quote:
Ripple requires more sensitive instruments to be measured properly


You can measure ripple with a digital multimeter in AC volts mode. You can also use a telephone and your ear.

 

[mechtech2]

After your good cleaning ans re assembly, a few light coats of Rustoleum spray paint will work well. Don't spray heavy coats that seep into the connection. A bunch of light ones.