[RE-wrenches] High specific gravity

[Brian Teitelbaum]

Mac,



Sounds to me that “someone” (ahem…) added some sulfuric acid to the cells
instead of plain distilled water.



Either that or there is some sort of contamination in there that is raising
the density or “weight” of the fluid beyond just what the proper amount of
acid would do. “Specific gravity” is just a measurement of how heavy the
fluid is compared to plain water (specific gravity of 1.00). Sulfuric acid
is heavier than water, so when mixed will increase the density and raise
the weight of the fluid. Temperature effects the measurement too of course.



If it turns out that acid was added, you can balance them out by removing
some of the electrolyte from the high cells and replacing it with distilled
water. It would be a process of trial and error to get them all the same.
Remove a little, add some water, equalize again, measure S.P. and repeat as
needed.



Leaving the electrolyte too strong will shorten the battery life, although
maybe not enough to go through this ritual.



Brian Teitelbaum

AEE Solar





*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Mac Lewis
*Sent:* Tuesday, August 12, 2014 6:55 PM
*To:* RE-wrenches
*Subject:* [RE-wrenches] High specific gravity



Hello wrenches,



I just went on a service call for a new client.  He had a bank of 4 year
old Interstate L16HCL batteries, 2 strings of 8, 48V system, 840Ahr.  We
went through the batteries and got specific gravity on all of the cells
post-equalization.  I was a bit surprised to see some very high numbers ie
over 1.32 for the specific gravities (higher than my refractometer goes).
 The specific gravities were all over the place, but I haven't seen numbers
this high.  I don't have a great explanation.  He has a stacked 3648 VFX
Outback system, and the set-points were 58.8V Absorb for 2 hours, and 62V
Equalize for 2 hours.  He has a decent amount of solar (about 3400W) and a
1000W wind generator.



Any ideas why the specific gravity is so high on some cells?  Also, is
there anything wrong with having SG this high, post-equalization?  For this
very standard battery, what settings do you go with (Bulk, Absorb, Float,
Eq, and times for Abs and Equalization).



Thanks in advance






-- 







Mac Lewis

"Yo solo sé que no sé nada." *-Sócrates*
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