High Specific Gravity- how to "fix" it

System

Does anybody have experience with "fixing" a battery that has too high of a specific gravity. I am dealing with a new set (6) of 8L16's that are sitting at 13.1 (in pairs) and after a deep discharge they steady out at 12.8

These batteries are in PNG, and we dont always get good acid over there ;(

Currently the S.G. is off the chart.
Can the electolyte be dumped out of the batteries, water added, charged up, and then add acid as needed to reach 1.275 S.G.?

Any ideas (preferably ones that you know work)?

Can anyone give a general prediction about how much this will shorten the life of the batteries to run them like this... can we get 7 months out of them?

Thanks!

Windsun

Re: High Specific Gravity- how to "fix" it

It could be done, but if you only need them for 7 months not sure it is worth the effort.

What you would have to do is make sure they are fully charged, then dump all the acid into something safe (good luck on that..). Make sure it is fully mixed, and measure the SG with a good hydrometer. Then dilute it down as needed with distilled water.

And then the fun part of putting it all back into the batteries, you would have to make sure you get an equal amount in each cell.

Vic

Re: High Specific Gravity- how to "fix" it

My wonderment is HOW you are measuring the SG of the batts ?

Are you certain that the hygrometer is accurate ?

And, if the electrolyte is low due to evaporation or reduction of the water in the electrolyte, then the measured SG would rise. Also be certain to compensate for the temperature of the electrolyte, unless the hygrometer is already compensating.

My random thoughts YMMV so on. Good Luck Vic

niel

Re: High Specific Gravity- how to "fix" it

if the batteries are new then let it go as they are under warranty. they will often be high when new, but off of the charts is questionable and i suggest you contact the manufacturer if the hydrometer is reading accurately and too high.

BB.

Re: High Specific Gravity- how to "fix" it

And just to confirm, your hydrometer is clean (no oil on float), accurate (pure water = 1.0), and that there are no gas bubbles on the float (if batteries are freshly charged, the electrolyte may be "hydrogenated" and small gas bubbles collect on the float).

And if you check another battery (car, truck) it gives "reasonable" readings.

-Bill

icarus

Re: High Specific Gravity- how to "fix" it

How high is "off the chart"?

I would lean toward a funky instrument. I had a hydrometer once where the float would stick on the bulb and give me real odd readings until I figured out what was going on.

Tony

System2

Re: High Specific Gravity- how to "fix" it

Looks like they may have been filled with 1.300 SG at sea level. i havent been able to find a chart that adjusts for elevation... 5000 ft. Anybody? The hydro calibration tests are forthcoming.

BB.

Re: High Specific Gravity- how to "fix" it

There should not be any altitude offset for specific gravity... The only correction is temperature (and battery state of charge which depletes the acid in solution, leaving water behind with a spg of 1.0 ).

Since water/electrolyte/acid is not compressible, the local air pressure/altitude will not make any difference.

-Bill

BB.

Re: High Specific Gravity- how to "fix" it

If you want to try and dilute the battery electrolyte to normal specifications--this is some math that should help (as always, check the math yourself--never trust anything you read on the Internet).

Example #1 (assume you dump the entire battery contents of 1.30 electrolyte into a clean plastic or glass container and want to dilute with 1.00 spg distilled water down to 1.275 spg):

Let X=amount of 1.00 water you want to add, and assume 1,000ml / 1.0 Liters is the amount of 1.300 liquid electrolyte per cell; the result will be 1.275 spg electrolyte--ready to pour back in battery:

1000ml*1.30 + X*1.00 = (1000ml+X)*1.275
1300ml + X = 1275ml + 1.275*X
1300ml - 1275ml = 1.275*X - X
25ml = 0.275*X
25ml/0.275 = X = 90.9ml of 1.0 spg distilled water per 1,000ml of 1.30 electrolyte

The other method, assume you know that the battery has a capacity of 1,000ml per cell. The cell/battery is charged, and the spg of the electrolyte is 1.300. And you want to remove Xml of 1.30 electrolyte and add Xml of 1.00 spg distilled water to the cell to get 1.275 spg electrolyte (basically, draw out just enough of the existing electrolyte and then add back 1.00 distilled water):

(1000ml - X)*1.300 + 1.00*X = 1000ml*1.275
1300ml -1.3*X + X = 1275ml
1300ml - 1275ml = 1.3*X - X
25ml = 0.3*X
25ml/0.3 = X = 83.3ml (draw 83.3 ml from charged battery, add 83.3ml of 1.00 distilled water for 1.275 spg)

So, charge the battery, draw 83.3ml per 1,000ml of battery cell capacity, then add back in 83.3ml of 1.0 distilled water. Put battery on equalize (for an hour or two--whatever is the Mfg. recommendation) to generate some hydrogen to "stir/mix" the electrolyte with the distilled water.

The numbers look "sane"--so I think I did everything correctly.

But, again with the warning. I have forgotten most of my 7th grade math--so double check my equations and math to your satisfaction before doing attempting the work.

Also, I used a place holder for battery capacity (1,000 ml / 1.0 Liters)--you will have to either measure the amount of electrolyte you drain, or ask the vendor for the cell fluid capacity.

-Bill