I've had an issue with a poorly charging system, and have yet to determine the source of the problem, (bad ground wires, alternator...). In the mean time, something is confusing to me.

I've had to charge my battery, and the charger registers just above 3 amps when hooked up, and slowly approaches zero when it's fully charged. While it is charging, aren't there supposed to be bubbles in the battery fluid? There are none in mine. The battery is 12 months old.

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1967 Barracuda 225

Bubbles = overcharging.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Ok. First reason for my thinking there should be bubbles, is that I've been told that in the past.

Second reason is that I've been studying up on electricity with a book on the fundamentals, and I had just read about primary cells with dissimilar metals as electrodes, and sulfuric acid, and how the electrochemical reaction produces hydrogen gas. And I put together the fact that on top of my car battery, there is a warning about explosive (hydrogen?) gasses.

Then today, I read further about Lead-Acid Storage Cells--which is a secondary, or storage cell--and the chemistry seems to be different, and a bit more complicated, and didn't describe any emission of gas, but only the conversion of lead peroxide (+) and "spongy lead" (-), (which I've never heard of), via sulfuric acid into lead sulfate coating both pos. and neg plates. And recharging the lead-acid cell reverses this reaction, turning the + plates back into lead peroxide, and the negative plates back into spongy lead, and the electrolyte back into sulfuric acid.

So this leads me to two more newer questions:

1) How does over-charging produce gas bubbles?

2) Why does the top of my car battery warn of explosive gasses, if not hydrogen gas? (Is sulfuric acid explosive/flammable? The exhausted electrolyte is diluted with water, so that can't be flammable).

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1967 Barracuda 225

Electrolysis is the process that cracks the water molecule into its component oxygen and hydrogen atoms. Sulfuric acid is not explosive by itself but its highly reactive which can produce an energetic reaction with a base. The sulfuric acid, H2SO4, has plenty of material there for the reaction and the byproduce would be some SO2 and SO3 which would be a brimstone smell.
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Toyota Motor Triathlon Race Car

As I recall from my theory classes years ago (ugh = so long ago) when you charge the battery the charging current moves the electrons from the positive plate through the medium (electrolyte) back to the negative plate (could have that backwards).

During this process gases from the process can accumulate inside the battery. The same holds true when the battery is in normal use. Typically the battery is sealed but there is always a vent present - this comes in several variations - through the removable lids to access the cells or in a completely sealed battery there is normally a venting valve.

The gases should not cause you any trouble since you need a certain percentage of oxygen mixed with them in order to promote ignition as well as something to ignite it in the first place - so no open flame or spark around the battery is a good idea.

As far as boiling the electrolyte goes if you have a really old charger that has no timer feature once the battery is fully charged and can no longer move those cool little electrons from one plate to another the current between the plates will further warm the electrolyte to a point that it can start to boil.

Thats the best I can offer - its been over 20 years since I studied batteries but I think its basically correct - hehe

Peace

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The car I am restoring is a 1971 Valiant 4 door with a slant 6 - 225 engine.

Something about that confused me recently.

Tried to get a motorcycle started that sat for a year. Was using a good battery from another bike but it ran down before the bike started. It was the correct size for both bikes. Hooked it up to my Schumacher 1.5 amp battery maintainer with the caps off the battery and let it sit overnight. Saw a few bubbles, so I knew it was charging. It stops charging when the battery voltage is back to normal.

Next morning, the battery acid had overflowed onto the table it had been sitting on. The battery didn't seem to be damaged, though.

What I want to know is why this happened. I have a lot of guesses, but that's all they are. I've used these chargers on cars, bikes and riding mowers for years during storage with no problems. The battery caps were not removed any of those times.

Don't mean to go off-topic with this post, but Dan's post that bubbles mean overcharging and the fact that this charger is supposed to shut off automatically got me wondering about it again. This is a great place to learn, so maybe someone can fill me in.

Dad told me decades ago that bubbles mean the battery is being charged and that's good. Now I'm not so sure.
The older I get, the more I find that a lot of things I was taught may not be true after all.

Bubbling is normal during charging - gases created during the process will naturally rise to the top - easiest check to see if its actually boiling is simply to feel how warm the battery actually is. If it is too hot there is something wrong - bad battery or a faulty charger or possibly the charger is set wrong. Some chargers have two voltage settings - 6 or 12 volt. I always thought motorcycle batteries were 6 volt - perhaps your charger was set to 12 volt which would not treat a 6 volt battery very well over night.

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The car I am restoring is a 1971 Valiant 4 door with a slant 6 - 225 engine.

It's been a very long time since bikes had 6v batteries - at least regular street bikes, which is all I play with.

The charger was set to the correct 12 volts and I didn't see anything unusual, so I figured it was safe to leave it overnight. One of my many guesses about this is that it never stopped charging the battery. But the status indicator on the charger said it was fully charged in the morning.
I didn't actually see any fluid leak, just the damage on the table.

Could 1.5 amps have been too much current? The battery is fairly small, off a 600cc Honda. I've left the same charger on a Honda 250 (with a smaller battery) for months at a time with no evidence of overflowing.
Should I have left the battery covers on? This was the only time I've taken them off during charging, and the only time acid came out of the battery.

The fluid level had been a little low in some cells before charging, so I put some distilled water in the low ones up to the top of the battery. There was still room for expansion above that - about 3/4" to the top edges of the battery cap for each cell. Maybe it was overfilled?

that was probably it - the cells just need to be fully immersed so slightly above the cell is just fine

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The car I am restoring is a 1971 Valiant 4 door with a slant 6 - 225 engine.