Battery Boil & Water

[a64pilot]

Yet, you never mentioned you weren’t at the boat, but you have several posts in the forum about being on a ball in S. fl.

[sailorboy1]

Originally Posted by a64pilot

Yet, you never mentioned you weren’t at the boat, but you have several posts in the forum about being on a ball in S. fl.

I just looked through the thread and see I did a couple of times. But even if I hadn't it was just fair game to trash post at me and it was allowed, even after I reported. So I'm not in the mode to accept any of people's "reason" for why it was OK to trash on me me, but unacceptable if I pushed back.

[Jason Flare]

Would a battery that is “gassing” leave water or acid on top of the battery?

[sailorboy1]

Originally Posted by Jason Flare

Would a battery that is “gassing” leave water or acid on top of the battery?

And since people are now word gaming, would a “gassing” battery result in acid in the battery box (and only on that battery in the bank)?






I should just go out on deck an hit my toe with the winch handle

[Dsanduril]

Originally Posted by Jason Flare

Would a battery that is “gassing” leave water or acid on top of the battery?

It can. The gas is the result of electrolysis of the electrolyte and the gases are hydrogen and oxygen. Many (most?) batteries have caps that are designed to re-combine those gases and have the resultant water drop back into the battery cell. However, if the gas does escape the battery it will generally recombine (or combine with atmospheric oxygen) outside the battery and the droplets will land back on the battery.

For the most part the sulfur ions stay inside the battery during this process, so in theory you would have water, not acid, but it seems that most batteries always give up a bit of sulfur or have it on the case (from a dripping hydrometer, for instance) and so the liquid could be acidic.

[Kolchac]

You cannot connect the battery in parallel! It is a very crude mistake. You should disconnect batteries 1 - 3, or 2 - 4, or better "and". Put there switches. You can connect them only when they are being charged, or when you start the engine. I can explain to you why, but this, probably, you do not need.

[dbraymer]

Physics major and electrical engineer here: the battery that is closest to the load and or charge is used more.

There is no easy way to solve this. If you have the batteries side by side, and they are in series connected by proper gauge cables, the discrepancy will be small. You could consider simply swapping the batteries around per a schedule, If it bothers you, you could also go nuts and add additional cables that effectively make the load and charge cable lengths roughly equal.

This last idea is actually worthy of a thesis: analyze the entire electrical system, considering loads and charging, charging and depletion time ratios, wife using her hair dryer, and figure out how to wire the vessel to use all batteries equally.

But wait, I have real work to do...

[skenn_ie]

One cell gone short circuit or low resistance through the electrolyte.. That will bring more charging current through it AND drain the other batteries, quite likely shortening the life of the others. Watch it while charging. does one cell not bubble while the others do ? Check the other one in the series-pair too.

[suncat]

Originally Posted by Dsanduril

It can. The gas is the result of electrolysis of the electrolyte and the gases are hydrogen and oxygen. Many (most?) batteries have caps that are designed to re-combine those gases and have the resultant water drop back into the battery cell. However, if the gas does escape the battery it will generally recombine (or combine with atmospheric oxygen) outside the battery and the droplets will land back on the battery.

For the most part the sulfur ions stay inside the battery during this process, so in theory you would have water, not acid, but it seems that most batteries always give up a bit of sulfur or have it on the case (from a dripping hydrometer, for instance) and so the liquid could be acidic.

Hi,
This just peaked my interest on the chemistry of the gases emitted from the battery. I did a quick web search for the "caps" you describe. They do exist but I doubt they are on "most " batteries. It seems they have a catalyst in the caps and are about 8 dollars per cap.

and at least one author reminded me that the oxygen and hydrogen do not recombine at normal STP( I think he used the term endothermic reaction) but vent into the atmosphere.

all the best,

[Dsanduril]

Originally Posted by suncat

Hi,
This just peaked my interest on the chemistry of the gases emitted from the battery. I did a quick web search for the "caps" you describe. They do exist but I doubt they are on "most " batteries. It seems they have a catalyst in the caps and are about 8 dollars per cap.

and at least one author reminded me that the oxygen and hydrogen do not recombine at normal STP( I think he used the term endothermic reaction) but vent into the atmosphere.

all the best,

You are absolutely correct, and I am flat out wrong. Well, technically, they will combine at STP, but the half-life of the reaction is estimated to be greater than the age of the universe - it will take a very long time to see a droplet of water regardless of the theory the age of the universe to which you subscribe.

The really sad part is that I knew that, but somehow in typing what I said made sense.

[captainwd40]

Just a quick word to the wise ......

Batteries should never boil. Bubbles are okay ..... just not a boil. AND BE VERY CAREFUL ..... battery bubbles contain hydrogen gas that is very easily ignited with a simple spark.

I agree that the battery boiling is probably associated with a shorted cell.

Current 'runs downhill' like water and will all go down to the battery with resistance lower than normal.

I recommend you replace it!

[sailorboy1]

Sometimes it just cracks me up

[David Mathis]

I've been having the same problem with my 43' Wellcraft, twin Caterpillars, which has two banks of two group 27 batteries. The aft battery on the starboard side has always used much more water than the other three. A few years ago, all batteries were replaced then the starboard aft battery went bad on a trip. It was found to have little water left although the other three batteries took only a few ounces, maybe an ounce or two of water per cell. It was only a few months old so it was replaced under warranty. A couple months later the replacement battery had the water (OK, acid solution) down to the top of the plates with all cells of the other batteries full. It continues to boil off the water and I continue to add more with no apparent adverse effect.
The boat is on the hard in upstate New York so I'll have to wait until the spring to try replacing the ground cable to that battery.

[skipgundlach]

At the risk of duplication as I skimmed the arguments:

I had to replace a pair in a series/parallel setup just like yours.

The voltages across the series pairs were the same - but the individual voltages were not, and heat resulted as the bank attempted to charge what turned out to be a dead-cell battery, and overcharged the other in the pair.

If all 4 of your batteries have the same voltage and temperature, nearly certainly it's a location or connection issue. If not, it's a clue to look further with some of the other suggestions. FWIW MaineSail is a reliable source of info (not that many others here aren't).

Ultimately, however, specific gravity readings for comparison and temperature-adjusted readings for actual state are needed as to the health of your bank and its individual components. The one shown in the pic is quick and easy but some boat bucks; I use the turkey-baster style with a thermometer and scale for added or deducted values based on temperatures. I also follow the recommendation of Trojan (my manufacturer) to draw and forcefully return 3 full tubes in order to assure mixture (avoiding stratification which can occur if equalization has not occurred recently) before taking the reading. That has the added benefit of allowing my thermometer/temperature-adjusting meter to stabilize if there are differences between cell temperatures.

However, if all are at the same voltage, aside from the head-scratcher of more water to one of them, it doesn't sound catastrophic, unlike the serially one-dead-cells on the ENTIRE bank (one on delivery, two a couple months apart almost 2 years in, and the last at 2.5 year in), at each of my 4 locations...

[ramblinrod]

Originally Posted by Dockhead

You are correct. That's the way most of us use the terminology and so I was also thrown off by "boiling". I assumed he had a hot battery but now we understand it was just gassing vigorously.


Now things fall into place a bit; glad that the mystery has been cleared up.

Well, I’m not sure what poll or survey was done to determine the battery terminology used by “most”, but I will concede that different individuals may use different terminology, and that’s OK if it obvious what they are referring to.

I’m sure the self-righteous will insist that all use their preferred terminology.

Never-the-less, in my opinion (and that is the only one that really matters to me) a battery “boiling” is commonly used to describe a battery that is gassing vigorously, to the extent that electrolyte may discharge out the vent caps, such as is common with excessive charge voltage, whether related to shorted cell or otherwise.