From: muratlanne@gmail.com   
      
    wrote in message   
   news:7uovladf7j2kutbf192hv5jk20h5l7si36@4ax.com...   
   > On Fri, 22 May 2015 17:19:05 -0400, "Jim Wilkins"   
   >  wrote:   
   >   
   >   
   > A different story with a bank of 8 batteries to charge on a daily   
   > basis. I had a rather expensive "intelligent" 4 mode charger.   
   > Didn't help when over the winter the power got disconnected, the   
   > batteries got low, and they froze. AGMs are much more tollerant that   
   > way.   
      
   I agree that AGMs are less fussy. When I was the battery tech at   
   Segway I learned how to charge and maintain new-tech sample batteries,   
   mainly various types of Lithium, with voltage and current controlled   
   lab power supplies. At another contract job I had some medical   
   instrument lead-acids to repair, and the battery makers' data sheets   
   showed that the same methods would work well. The procedure is simply   
   to follow the data sheet's recommended voltages and currents.   
      
   Automatic chargers are faster, of course. Manual charging allows   
   higher voltage at limited current to prolong the life of old   
   batteries.   
      
   I've built my own metered power supplies for this and similar tasks   
   like reforming old electrolytic caps, and haven't looked very hard at   
   commercial "intelligent" chargers with equalizing and desulfating   
   functions. My quick impression of them is that they employ an   
   open-loop brute-force method since they can't track electrolyte   
   specific gravity to know when to stop. Also they could destroy   
   attached equipment if they applied an effective voltage to a bad   
   battery that was still connected to it. This task can be dangerous and   
   requires some care and knowledge.   
      
   One of the Segway engineers left his very sophisticated charger for RC   
   airplane LIPO batteries in the lab. Other than balancing multicell   
   packs it did the same things we could with the lab supplies, but   
   faster since it could monitor voltage and terminate a fast charge. It   
   wasn't any better than a lab power supply when we needed to set the   
   top-off voltage and current limits from a battery supplier's data   
   sheet.   
      
   http://tec.gov.in/pdf/PlanningGuide/MonitoringofVRLAbatteries.pdf   
      
   >>The battery in my truck is from 2002 ...   
   >   
   > For normal SLA duty I've gotten over 12 years service out of flooded   
   > batteries too, in daily use.   
   >>   
   >>Flooded batteries require more attention, but they also allow it   
   >>since   
   >>I can add water and check specific gravity. Equalizing has been less   
   >>effective for me on second-hand VRLAs.   
   >>   
   >   
   > And how old were the "second hand" vlra batteries?   
      
   The handwritten dates on the PowerSonic 12V 18A VRLAs are from 2009 to   
   2011. I think that's when they were checked after scheduled removal   
   from service.   
      
   -jsw   
      
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