Battery water falls very slightly in Cell Six?

[profdant139]

I usually check my battery water every month. (These are group 31 flooded marine batteries from NAPA.). I almost never have to add any water.

I keep the batteries hooked up to a Battery Minder Plus, one of those pulsating things.

This summer and fall, due to some fairly serious medical issues in the family (but not my immediate family), I skipped my usual battery water ritual for about four months in a row.

When I checked them the other day, five of the cells on each battery were fine. On both batteries, the sixth cell (the one nearest the positive terminal) was down about a half an ounce -- almost not down at all, but still different from the other cells.

The specific gravities of the cells were uniformly good, according to my tester.

I'm not worried about this phenomenon, but it is puzzling. Why would one particular cell lose a tiny amount of water?

[profdant139]

Gjac, those are good tips -- thanks! And to answer your question, we are "electrical minimalists," just like you are. It is hard to say how long our batteries could last -- since we always hook up to our 120 watt portable solar panel, we almost never have to run the generator -- less than once a year!

But my best guess is that under ordinary circumstances (warm weather for good battery performance), we could go for about four days before the battery reaches 12.1 volts.

Cold weather is different, because we have to run the furnace during shower time, which uses a lot of juice. That would limit us to three days without solar power or the generator.

[pianotuna]

Steve,

If the plates are covered:

1. charge batteries to 100%
2. add distilled water
3. discharge at high rate
4. fully recharge.
5. optional--equalize the battery.

If plates are not covered, add enough distilled water to cover them.

[StirCrazy]

MEXICOWANDERER wrote:


Don't add more than 5 oz of water to a car jar battery cell then just let it sit. The electrolyte must mix and it cannot do it withour help. Load the battery bank so when the charger resumes charging it will go into bulk mode.

are youi talking about discharging it after you add thr water? everything I have been taught and read was always to add water to a fully charged battery as the water/solution expands as it charges.

Steve

[Gjac]

Hi Dan, I am guessing you camp similar to me, with minimal electrical requirements. Basically water pump, lights and refer? If so how long can you go without charging before your batteries get to 12.1 v? Do you have a way of equalizing your batteries with your current charger? If not a portable charger like the 40 amp Stanley or B&D is a good thing to have to do this. It will keep your batteries healthy longer. Lastly when these marine batteries do fail I would replace them with 6v GC batteries if you can fit them in your battery compartment, they will serve you better for dry camping and last longer.

[pianotuna]

profundant139,

Just below the ring may be the best.

[Gdetrailer]

profdant139 wrote:
These are five year old marine batteries -- they have never dropped under 12.1 volts, measured while resting. Always topped up. Not a hint of trouble so far.

5yrs? They are in the "prime of their lives", no reason to worry at this time, should be able to get another 5 yrs as long as you promptly recharge after being discharged and don't mind a slight lower capacity towards the 10 yr mark.

profdant139 wrote:
Based on the consensus of the posts above, it looks like I should not worry about a tiny drop in the water level of one cell over a period of several months.

CORRECT!

The cells are not 100% perfect, each cell will use slight different amounts of water which is normal and to be expected.

Think of it in a different way, in everything we humans make, there is a "tolerance", that tolerance can be graphed and you will sell a "bell shaped curve". As long as everything stays within the bell shaped curve tolerance all is well. I suspect you find it to be very rare that everything made will hit the center of the bell curved 100% of the time.

For more information on bell curves you can look and read up on mathematical statistics.

profdant139 wrote:
And someone wondered whether I really meant that it was down by a half ounce. That's really true. I measured how much I had to add to the cell to get it up to where there is a "meniscus" at the bottom of the fill tube. That's the curved lens shape on the top of the water.

I have been told that you add water just until that meniscus appears. If that's wrong, I am sure someone will let me know!!

The closer fill to the top actually can cause excessive water use/loss, my Dad taught me to fill to JUST BELOW the fill ring (not touching or not up in the fill ring). This gives the water bubbling up some breathing room when the bubbles break. Keeps the splashes lower and less chance the caps will get a lot of liquid on them which results in liquid being forced out the vents..

Overfilling is most likely a big culprit for terminal corrosion that some folks complain about.. I don't have that problem as you can see by the pix I posted.

In a nutshell, as long as the water is above the plates and just below the fill rings you are good to go.

Never want the water to get below the tops of the plates, that exposes the plates to the oxygen in the air and will degrade the plates fast.

[MEXICOWANDERER]

The watering issue is underappreciated. One of the sweetest attributes of an industrial battery is it's electrolyte capacity (includes GC batteries). An excess capacity battery has an improved service life of almost 20% all other things being equal. And that is yet another reason a super premium AGM battery like the Lifeline is superior --- the mat used in Lifeline batteries is 500% more expensive than ordinary AGM matting.

Don't add more than 5 oz of water to a car jar battery cell then just let it sit. The electrolyte must mix and it cannot do it withour help. Load the battery bank so when the charger resumes charging it will go into bulk mode.

The optimum fill point is to submerge the plates without encouraging burping. Of course AGM and sealed alternative chemistry batteries do not need this kind of maintenance.

My AGM lifelines have been offline since February. We shall see effects of this on a 10-year old accumulator including end capacity. I need to build another shop room. Work tables and tons of $$$$ shelves.

[profdant139]

Gjac, that is a great idea about testing the hydrometer on distilled water -- it might be giving me "fake news" that all my cells are great when maybe they aren't! 😉

Someone mentioned that I am obsessing about my batteries. Guilty, with an explanation. We do a lot of boondocking, so if my batteries die, that would be a hassle. (Not a tragedy -- we would just pack up and go to an RV park.)

So although I am by no means a professional battery person (unlike a few of our members -- hi, Mex!!), I am always on the lookout for signals that my batteries are on the way out.

These are five year old marine batteries -- they have never dropped under 12.1 volts, measured while resting. Always topped up. Not a hint of trouble so far.

Based on the consensus of the posts above, it looks like I should not worry about a tiny drop in the water level of one cell over a period of several months.

And someone wondered whether I really meant that it was down by a half ounce. That's really true. I measured how much I had to add to the cell to get it up to where there is a "meniscus" at the bottom of the fill tube. That's the curved lens shape on the top of the water.

I have been told that you add water just until that meniscus appears. If that's wrong, I am sure someone will let me know!!

[MEXICOWANDERER]

Francis Freas Glass Works

[Gjac]

profdant139 wrote:


The specific gravities of the cells were uniformly good, according to my tester.

What kind of tester did you use? When I checked mine with one I had from Walmart my cells were always uniform also. Got another with floating balls and got the same results. They both read about 1.265. When I checked distilled water I got the same reading. My batteries don't slide out so it is difficult to get a tall one in there to test. So unless you can get in with a good hydrometer like a Frese you may not have an accurate reading. Check it with a glass of distilled water and see what it reads. Having said all that my cell closest to the positive post was also low. It also had a reading of only 1.5v with the charger on. All the other cells were about 2.5 v. Running an equalization routine fixed this problem.

[MEXICOWANDERER]

Using pure lead coated terminals at the battery.
Lead outside the battery acts exactly like lead inside the battery. It is very slow to corrode. I used to purchase lead coated copper terminals, from QUICK CABLE but I see they disappeared. Open ocean cannonball commercial weights and shotgun lead has gone the way of the Dodo. I can see shotgun pellets being banned, but few people can consume a 20 pound cannonball. I now pre-coat my terminals by dunking in a solder pot.
Again, this only makes sense if the terminal sits atop a flooded lead acid battery. Tin plating offers around 2% of the lifespan as a comparison.

[MEXICOWANDERER]

Try this,

Neutralize all acid on top of the battery, then Dry.

Spread a thin coat of vaseline or silicone grease around the offending post and cell then keep going to the nearest negative conductor which may be a battery hold down frame or strap. On a seemingly dry battery top I use diluted phenothalien and water pump spray. Acid reside will turn the solution bright red. Some spray cans of battery acid neutralizer will do the same thing at a higher cost.
Most of the corrosion you see on terminals is not from the lead. It's from the steel fastener. Somewhere here or at home I have boxes of 316 stainless steel bolts, nuts, and spacers. It ignores the corrosive effects of H2SO4.
My batteries have K Monel fasteners rescued from a scrap metal yard in Wilmington California. I cannot remember what I paid for them but it wasn't cheap 40 years ago. My 25-year old K-car has the original untouched battery cables.

[Fisherman]

I've had that same situation on most of my FLA batteries, one end (prob +) gasses off a bit more than the others. Batteries lasted up to 11 years.

[MEXICOWANDERER]

90 degree breezes and an off shore breeze presented the biggest challenge for me. You don't want to know the cost of 330 MCM cast lugs for my batteries. By the way the set voltages that Ford used was 7-1/2 and 15, with generators, and because they were generators the was -0- charging amps at idle, it was all discharge amps especially bad with headlights and heater fan going, at or just above idle.

So batteries cycled in the city. My radio drew 9 amps. With a 55 amp hour Group 2 battery and a 30 amp generator. The days of dry charged batteries, and polarizing generators, and sticking cutouts. I rejoiced when MoPar brought forth the first alternator in a car in 1961.