life expectancy of sealed & wet batteries [RE-wrenches]

Thu Jan 10 11:52:16 PST 2008

HI Dave see you at AEE in Feb
Darryl
--- "David Palumbo, Independent Power & Light"
<ipl at sover.net> wrote:

> 
> Wrenches,
> My experiences mirror Travis' on the sealed bats.
> But I have seen
> significantly longer life spans with wet cell
> batteries over my 23 years
> working with them. With L-16 size 10 to 13 years not
> that unusual in our
> off-grid systems. Golf Cart size we have seen a few
> systems get 12 useful
> years out of them which amazed me. We also have a
> number of systems with
> large 2v cells with no problems yet in 12 years so
> far. Properly sized
> systems with attentive homeowners is the common
> thread with all of these
> long lived battery banks. But I do have a theory
> about battery temperature
> also prolonging the life of these cells. Here in
> Vermont these batteries are
> 65 F in the summer and 55 F in the winter. We do
> know that higher battery
> temperatures yield higher storage capacity but
> reduce life cycles. Please
> note that we also have folks that use up an L-16
> bank in 3 to 5 years.
> 
> I have kept a set of Hoppecke FNC's (Fibered NiCads)
> going in my off-grid
> rental house for over 17 years now. Old timers will
> remember that our old
> friend Rob Wills (Skyline Engineering back then)
> brought these in from
> Germany as an improvement over the standard NiCads
> cells that many of us
> were frustrated with in the early 90's. The FNC's do
> not require the mineral
> oil float on the electrolyte's surface to reduce the
> onset of oxidation and
> electrolyte contamination. It appears that claim may
> be true, I have not had
> to recycle the potassium hydroxide electrolyte yet
> (in hard service since
> 1990). BUT the FNC's still had the same issues as
> the old technology Edison
> Cell NiCads, mostly amp hour capacity related
> problems due to the fact it
> was difficult charging them to 1.7 volts per cell
> and still operate an
> inverter. If they did not reach the 1.7v they lost
> most of their rated
> capacity. One or two cells would suddenly lose
> voltage and crash the
> inverter when it was assumed that the bank was
> reasonably well charged. You
> may remember trying 19 cells on a 24v system etc.
> trying to lick this
> problem, it didn't help very much, all things
> considered. The FNC's were
> very expensive and I had a lot of them that I
> removed from every one of the
> dozen systems that I sold FNC's with. Add that to
> several more systems that
> had the old reconditioned Edison NiCads (remember
> Pacific West, the NiCad
> reconditioning company? Now there's a story for
> another day) where not a one
> of them lasted more than a couple of years before I
> swapped them out for
> lead acids. I slept better after biting that bullet.
> The FNC's in my rental
> house are working really well for me after I figured
> out that you really
> needed three times the amp hour capacity as Rob
> originally recommended and
> have charged them to screaming high voltages. They
> are in a cold mudroom and
> work well there, one of the advantages of NiCads
> being that they do not
> loose as much storage capacity due to cold temps as
> lead acid cells do. I
> water them once per year and use an OutBack FX2012
> inverter that can
> tolerate the 17+ volts input that they get when the
> sun is out.
> 
> Will I see any of you in Arizona for the AEE dealer
> conference in early
> February? I'm looking forward to a change of scenery
> for a few days.
> -Dave
> 
> 
> <<We did about the same number of systems about the
> same time, many with
> Concorde AGMS and only one set still remains.  The
> others all died at or
> before 5 years.  Oddly, pretty much, the opposite of
> William's experience.
> We learned that even using the manufacturer's
> specifications for charging
> that grid tied systems (Trace SW's) are particularly
> hard on sealed
> batteries.  Our assumption was that since they
> constantly are charging the
> battery it dries the battery out.  One manufacturer
> essentially confirmed
> this but would not admit that maybe they needed to
> publish different specs
> for grid tied system.  It makes sense when you think
> about it...charging a
> battery for years on end can't be good for it even
> if it's just a tiny
> charge.  The one set of Concords that remains is
> probably still alive
> because we turned down the float setting to just
> above 12.7v (per 12v) after
> we started seeing all the other sets go.
> 
> In over 15 years in this business I've never seen a
> battery go anywhere near
> its rated cycle life.  Of course it's not like
> there's a "cycle counter"
> built into the battery so it's just the best I could
> estimate.  I've
> personally never seen a battery bank that I've
> installed last more the 10
> years.  We installed our first set of HUP's (a
> serious flooded battery)
> about 5 years ago and have no problems with them to
> date.  We've got a few
> sets of the big Surrettes out there on off grid
> systems.  While they are
> still alive after 5 years they are very much in need
> of what most would
> consider very high charge rates (over 200 amps) else
> they will quickly
> become severely sulfated.
> 
> I've seen T105'a go over 7 years and I've seen them
> die in just a few.  Same
> for L16's.  Owner involvement is absolutely critical
> to flooded batteries
> while there's not much they can do with sealed other
> then pay a twice what a
> flooded bank of the same capacity then watch it die
> sooner.
> 
> Travis Creswell
> Ozark Energy Services >>
> 
> 
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