State of Batteries

[Bill Balme]

Sorry - should have mentioned that the batteries had been charged before the above antics... HOWEVER, once I filled them with water, are they still considered fully charged? (In 4 8D cells, I used a gallon of distilled water - but in doing so, I filled them far more than I normally do. Normally I top them up to about 1/4" above the plates - but I gather it should be 1/4" below the caps. A gallon put me about half way between the two conditions...)

[Bill Balme]

Temperature reading - at the terminals - was 77F at the start. I think it rose to about 85F after 3 hours.

[Jbaffoh]

Originally Posted by hellosailor

Of course you DID also dip a thermometer into each cell, so you could compensate the hydrometer readings for internal battery temperature?

Funny how nobody makes a hydrometer with a thermometer built into it. Or have I just been looking in the "toy" aisles?

Yes they do!

Hydrometer, thermometer, battery tester, battery thermometer, battery hydrometer, wine hydrometer, beer hydrometer, beer thermometer by Francis L. Freas Glass Works Incorporated

Battery Hydrometer EZSP101

Edit:

And, of course, this: http://www.misco.com/products/7084VP%2B.html

[btrayfors]

Bill B: IF your highest seen voltage during the equalization process was 14.3VDC...

THEN either you have a bad battery or cell or, more likely, the batteries weren't fully charged to begin with.

Give them a full charge, preferably at 14.6 to 14.8VDC, and only then try the equalization cycle again. You should read a minimum of 15VDC during equalization and 15.5 to 16.5VDC is to be preferred.

Bill T

[deckofficer]

Bill T knows his stuff. Larmex mentioned "special caps" that I'm sure he was referring to Hydro-Caps and IMHO are worth it. Before switching to AGM I used the Hydro-Caps and cut water consumption by probably a factor of 10. If your in the market for new batteries and not ready to coin up for lithium, there is a 700 a/hr, 2 volt single cell AGM I've used that gives good, long life. Bill B, are you familiar with these batteries and if so, what do you think of them? SOLAR STAR VRLA AGM BATTERIES

[Bill Balme]

Bill T: How do I tell if I have a bad cell vs. the batteries not being fully charged?
I've given the range of SG's before and after the supposed equalizing - I'm guessing the cells are OK - right? In which case, the cells must not have been fully charged - OR, the equalization cycle of the Prosine Inverter is not working. How do I check that?

I'm thinking that if I charge the batteries - overnight - then do the equalization the following morning, if it doesn't get to 15+V something's wrong with the charger - rather than the batteries...

I only have a simple hydrometer - needle moves through an arc - is it any good? If it shows 1300, does that mean the cell is good? Is reading the SG right after a pseudo equalization flawed?

Appreciate the help...

[Jbaffoh]

According to Trojan, I would have a problem if any cell has a specific gravity +/- .015 of the others. What does Rolls say?

The pivoting needle hydrometers usually suck--and many of them need to be held just right (changing the angle can change the reading). With those, eyeball the levelness using the surface of the electrolyte as a guide. The turkey baster types (eye dropper if you don't celebrate Thanksgiving) are much better, but cheaper ones with smooth and narrow barrels tend to have the float stick to them. Better ones have dimpled barrels or floats to prevent sticking. Refractometers are great--and temperature compensated.

You must correct your readings for temperature. I don't know the nominal temperature for Rolls batteries, so I won't bother spewing Trojan's recommendations based on ºF readings.

[btrayfors]

Originally Posted by Bill Balme

Bill T: How do I tell if I have a bad cell vs. the batteries not being fully charged?
I've given the range of SG's before and after the supposed equalizing - I'm guessing the cells are OK - right? In which case, the cells must not have been fully charged - OR, the equalization cycle of the Prosine Inverter is not working. How do I check that?

I'm thinking that if I charge the batteries - overnight - then do the equalization the following morning, if it doesn't get to 15+V something's wrong with the charger - rather than the batteries...

I only have a simple hydrometer - needle moves through an arc - is it any good? If it shows 1300, does that mean the cell is good? Is reading the SG right after a pseudo equalization flawed?

Appreciate the help...

Bill:

I've never had any luck with hydrometers, despite having tried several rather diligently during a 2-year battery test. And, it's a sure way to get battery acid on you, your clothes, the battery box, boat, etc. And, in my experience, they're really not needed.

One way to test for a bad cell is to charge the batteries fully, then turn off all switches and disconnect a cable from each battery in the bank. This effectively isolates each battery.

Then, with a good digital multimeter check the voltage of each individual battery. If there is a significant difference between/among the batteries, then that battery likely has a weak or bad cell. If there's just a slight difference, it likely means that the capacities are slightly different or that all batteries in the bank didn't receive a full charge -- this can happen if multiple batteries in a bank are not connected correctly.

However, the fact that you measured SG approximately the same in all cells tends to indicate that the problem may have been elsewhere, e.g., the batteries not having been fully charged when you began.

It takes quite a while to reach full SOC and, very important, it takes a sufficiently high voltage. Most chargers/regulators/controllers/etc. are very conservative.

Flooded batteries and AGMs need 14.6 to 14.8VDC or so applied over a long period to reach full charge. How do you know when you've approached a 100% SOC? Monitor the amperage going into the battery. When it drops to a very low level...say 0.5 or 1.0 percent of the AH rating of the battery bank, then the bank is "fully charged".

In a recent test, a large new AGM battery on charge @ 14.4VDC for a 4-hour period with a very big charger (200% of the AH capacity of the battery)....was still accepting 0.9% of its AH rating. With a less powerful charging source, the battery would be accepting more than 1% after 4 hours @ 14.4VDC.

Bill

[hellosailor]

Thanks, jb. Artisan-made hand-blown hydrometers...no wonder they're not in my local auto parts store. And with no prices listed, I'm afraid to even ask.