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Pouring Coke on a Battery

I’m surprised Tom and Ray hadn’t heard of this. My dad ran a shop when I was in high school in the late 70’s and early 80’s and we always used Coke, or whatever kind of soda we happened to be drinking, to clean corrosion off batteries. Soda (all kinds) has phosphoric acid and/or citric acid to give them a sharper flavor. It’s a very, very mild acid, but it’s enough to dissolve the corrosion on battery terminals without harming anything else.

Here’s the rub: one hears stories of various soda pops working, via their acidic action. Even more common is the baking soda paste idea, via it’s strong base action. So which is it? apply a base solution or apply an acid solution?

my “home - ec” teacher in 7th grade - Norther New Jersey - 1959-60 told us that we shouldn’t drink coke because her brothers and boyfriend used it to clean their boat batteries…i guess she thought it would eat our stomach linings - not to mention our teeth, etc… so this wasn’t new to me - nor was the baking soda paste concept…

My husband was also surprised Tom & Ray didn’t know about Coke to clean battery terminals. Even I knew that, and I am not privy to the inner workings of cars. I learned the trick from a (hold your boos & hisses for a second) BP commercial during the 70s. Back then BP ran a few commercials on how to improve your car’s efficiency and other simple tips on car maintenance, including the one using Coke or similar soda to clean battery terminals. (Check YouTube for a BP ad on avoiding jackrabbitt starts, dated 1973) AFter learning this tip, there were jokes about the fact that if there’s anough acid in Coke to clean a battery, what was it doing to your stomach … didn’t stop us from drinking the stuff.

I just heard of this. I will try the idea one of this days. Thank you. :slight_smile:

[i] My husband was also surprised Tom & Ray didn't know about Coke to clean battery terminals.[/i] 

I am almost sure I heard them talk about that one on their show some years ago. Like me maybe they just don’t remember.

Many times with battery cleaning the goal is too neutralize the acid that is present,what do you guys have against baking soda, save the cola for refreshment,or are we talking about McGuyver type situations?

In addition to the flavoring acids, carbon dioxide in water solution forms carbonic acid, also relatively mild. Perhaps a further clue to the effectiveness of these off-label uses for “soft” drinks may be found in this photo:

I’ve previously heard of using Coke? (and similar products) to clean driveway stains, toilet bowls, and for dissolving pennies and eggshells, but I’d be leery of pouring any kind of water solution onto battery terminals.

I remember coke syrup often being used as a penetrating fluid to loosen frozen nuts-n-bolts. You didn’t want any to spill on your car paint. I believe you can still buy coke syrup in pharmacies.

Diluted vinegar is cheaper and less messy.

The hydrochloric acid naturally produced by the glands that make the gastric juices that digest food in your stomach is way stronger than anything in Coke.

Coke may contain phosphoric acid but, as GeneralE points out, it – like all carbonated drinks – also contains carbonic acid, and that’s what eats the battery fuzz. The chemistry involved is the same as with the baking soda Ray mentioned as a home remedy:

When carbon dioxide is dissolved in water, a portion of it combines chemically with the water to form carbonic acid:

H2O + CO2 -> H2CO3

As acids will do in water, the carbonic acid tends to dissociate, releasing positive hydrogen ions (the hallmark of all acids) and – get this – negative bicarbonate ions:

H2CO3 <-> H+ + HCO3-

Astute Car Talk listeners know baking soda’s chemical name is sodium bicarbonate; it’s a salt (NaHCO3) that also tends to dissociate in water to yield bicarbonate ions:

NaHCO3 <-> Na+ + HCO3-

I’d be on shaky ground to guess exactly how it interacts with lead oxide (or whatever that whitish crud is), but bicarbonate is the active ingredient. Which means that ANY carbonated beverage – Coke, Dr. Pepper (Yankee or Texan), or even humble seltzer – will get the job done. The fizz eats the fuzz.

Cleaning my battery terminals with coke kept my 76 corolla running for the entire summer of 1985, back when I couldn’t afford a new battery. I just shared a bit of the can that I was drinking at any given moment with the car. I also used 7-up in a pinch. Works like magic, but I also rinsed off the goo with water afterward, so that coke wouldn’t get down inside the cells. Not sure that was so smart, but it worked!

I’ve always used baking soda; brushed well; then rinse well with water. Not so much to clean the posts (wire brush for that) but to get the excess ‘acid residue’ off the outside of the posts and connectors; sides of the battery; and battery tray.

BUT, with either method, you don’t want to get it inside the cells. Keep the caps securely closed.

Tap hot water does just as good a job as any soft drink, and will not leave a sticky mess behind. I used to do this as a courtesy for customers all the time. They really thought it was something to see a clean battery, even though it took me 20 seconds to do the job and cost nothing.

"Diluted vinegar is cheaper and less messy.

The hydrochloric acid naturally produced by the glands that make the gastric juices that digest food in your stomach is way stronger than anything in Coke."

And so is aqua regia. So? Are you suggesting vomiting on the battery or just trying to show off?

As for vinegar, why dilute it? How parsimonious are you? Anything you can put in your mouth should be safe for your battery terminals.

Working at GM during the heyday of leaking postive terminals on Delco batterys gave me plenty of oppourtunitys to clean up acid spills, no one ever used any product other than baking soda and plenty of water.

These leakages would damage alot of components making a thorough clean up and repainting (from a spray can) necessary. You really wanted to make sure all that spilled acid was neutralized.

Soda water gets my vote. Used it for years and it works like a charm…no sticky residue left behind like Coke does. I couldn’t believe the guys didn’t know it was the SODA in the Coke that made it work!

i never new that coke would work to get the erosion off of a car battery

The substance that forms on battery terminals is solidified sulfuric acid, leaked from the battery. The reason why carbonated water or baking soda mixed with water works so well is it neutralizes the acid. Here’s the kicker: carbonated water acts equally well as both an acid or base neutralizer so while you can clean your battery with a can of cola, that same can will also help you out if you spill lye on your hand. It doesn’t matter which brand of soda is used as long as there’s a lot of fizz.

One other thing regarding the call, another incentive to steal a car battery is for the lead.

Thank you! I was pretty sure it had to do with the carbonation and not the phosphoric acid, but I’d have been hard pressed to explain it. Plain soda water should do the trick just as well as any other flavored beverage.