[RE-wrenches] Corrective EQ question

[Kent Osterberg]

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 at positiveenergysolar.com_ <mailto:Allan at 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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