Allan,
My first thought about the high s.g. measurements is that the
electrolyte level may have been low when the measurements were made.
When full, there is about a liter of electrolyte above the plates in a
L16. The s.g. will rise by 0.03 if the electrolyte level is at the top
of the plates.
Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemountainsolar.com
t: 541-568-4882
On 6/1/2012 1:28 PM, Allan Sindelar wrote:
Wrenches,
A long-time off grid client has a 48V Outback VFX system, with 1,680
watts of PV and two strings (16 batteries total) of Deka L16s,
installed last October. The array is undersized, as the system is
running three households; one efficient home and two single-person
tiny homes, but still too much for the system. We learned a few weeks
ago that the system had apparently stayed at 30-50% SOC for the entire
winter (this is approximate, as her TriMetric monitors would
eventually drift away from % accuracy if never allowed to get full and
reset). Eventually the batteries became sufficiently sulfated that the
system began shutting down.
As the batteries were nearly new, we figured that the sulfation had
not yet become permanently crystallized, and they could recover. We
initiated a long "corrective equalization" from her combined generator
(45A DC from the single inverter) and MX60 controller, for a maximum
C/12.5 charge rate; less in proportion to any loads that were on while
charging. She ran this procedure for three hours/day for five days,
and when that offered only partial recovery (as measured by specific
gravity measured with a refractometer), ran for six hours/day for five
days. During this time the MX60 was also manually set to EQ each
morning, with a 62V EQ voltage and 3 hour EQ time, so that the array
would add its amperage to the gennie until the batteries had been
above this setting for three hours.
We went out there yesterday, arriving while the EQ was in process. All
of the cells had recovered, as measured by SG. SG readings were all in
the 1.280 - 1.300 range, with most above 1.290. We had never seen SG
readings this high before. Given the situation and the back story,
should we have any concern about the high SG readings?
Thank you,
Allan
--
*Allan Sindelar*
_Allan@positiveenergysolar.com_ <mailto:al...@positiveenergysolar.com>
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*
3209 Richards Lane (note new address)
Santa Fe, New Mexico 87507
*505 424-1112*
_www.positiveenergysolar.com_ <http://www.positiveenergysolar.com/>
*
*
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