SG of a few Rogue Cells.??

[Matrix]

Let me begin by saying thanks to all who have so patently answered my questions so far. I know I come with more questions than answers, but I am so new at solar and flood acid batteries.. .and just learning to walk, I don't want to break anything.

Tonight I am trying to wrap my head around the Specific Gravity of the battery bank cells. Not testing or load calculating etc. Or Hydrometers, thanks to this forum I'm getting that pretty good. Just the numbers.

I have been carefully monitoring my new Trojan L16H-ac battery bank the past few weeks since installed. At first all cells at fully charged were at the same SG.... 1.277 +. But Now after 2+ weeks I have 3-4 cells that are lagging, and one that has leaped ahead.

I have 3 cells that have fallen behind the others by about 15-20 points at full charge of the bank. I have EQed them for 2 hours 2 nights ago testing at the 1 hour point and stopping when individual cells stopped rising in SG. This did not bring all cells into equal range. 3-4 cells still lagged 15 or so points although now at 1.277.

If the higher cells are at 100%/1.277 sg, Some of these "lazy" cells will be at 1.260. If I charge until those cells reach 1.277, most of the other cells are at 1.285 to 1.290... With one cell being over 1.295.

All 4 batteries are reading the Same volts within 1 or 2 hundredths of a volt. And Trojans charging guide says u should EQ if cells differ by .030 in any cell. I don't have that large of a gap.... So is 15-20 points a problem or typical for a few cells? How do I correct this? I EQed, and it didn't help. So do I EQ longer or just let it ride?

AND if I should just let it ride... Where do I charge to? To 100%/1.277 sg of the highest cell or the lowest cell? What is considered fully charged?

Any ideas?

[NEOH]

Matrix ,

You should charge your battery bank until the SG stops rising, not when the SG hits a specific value.
You want to remove all sulfate from the plates daily, which means maximum SG reading.
During the daily charge is the electrolyte bubbling in every cell for about an hour?
If not then you are under-charging on a daily basis - not a good idea.

[Matrix]

Matrix ,

You should charge your battery bank until the SG stops rising, not when the SG hits a specific value.
You want to remove all sulfate from the plates daily, which means maximum SG reading.
During the daily charge is the electrolyte bubbling in every cell for about an hour?
If not then you are under-charging on a daily basis - not a good idea.

So taking the cells that are rising to nearly 1.300 is not a problem?

Yes, I am getting daily "bubbling" or gassing, and I believe it to be every cell, but I will check more closely.

[NEOH]

Charge the battery until the SG reading stops rising for two consecutive readings, taken 1 hour apart.
That proves that all of the sulfate is removed from the plates and is dissolved into the electrolyte - where it belongs.
Hardened Sulfate is like cancer.
You should see a slowly rising SG readings as the charge tapers.
If you are seeing wildly varying SG readings as the charge tapers then you have a sticky float or bubbles or ??? = Bad Readings = unreliable.
The ability / skill to get very consistent readings in the same cell as the charge tapers is extremely important.

Note: no where in the above is any absolute SG reading ever specified.


From your Trojan Users Guide ...

Equalizing Charge
===============
It reverses the buildup of negative chemical effects like stratification, a condition where acid concentration is greater at the bottom of the battery than at the top.
Equalizing also helps to remove sulfate crystals that might have built up on the plates.
If left unchecked, this condition, called sulfation, will reduce the overall capacity of the battery.

Trojan only recommends equalizing when low or wide ranging specific gravity (>0.030) are detected after fully charging a battery.

1) Remove all loads from the batteries.
2) Connect battery charger.
3) Set charger for the equalizing voltage
4) Start charging batteries
5) Batteries will begin gassing and bubbling vigorously.
6) Take specific gravity readings every hour.
7) Equalization is complete when SG values no longer rise during the gassing stage.

I do not see any SG value stated in the above instructions.
Do you?

I find it hard to believe that you are bubbling all of the cells for an hour during Daily Charge, and yet those cells have a low SG readings.
20 Points low is 90% SOC

[Matrix]

Charge the battery until the SG reading stops rising

I find it hard to believe that you are bubbling all of the cells for an hour during Daily Charge, and yet those cells have a low SG readings.
20 Points low is 90% SOC

No I dont see any SG numbers in the EQ section from Trojan, but they do note that a fully charge battery reading is 1.277.

I am not seeing 20 points low with some cells stopping at 1.260.... I can have gotten even the lowest cells to 1.282 ... but then the highest cells are at 1.295 to 1.300. So there is a 15-20 point gap. Is the gap a problem if all the cells rise to Trojans 1.277 or above? But I guess not. Just charge fully to the lowest cell to get rid of all Sulfate.

I am going to do as u suggest and charge and watch the SG every hour in all cells. Thanks for the advice.