Gel Cycle Life [RE-wrenches]

[Clive Wilkins, PowerSense]

Hi Doug, I'm a bit confussed here....so who make these batteries.....MK  ,
Concorde, or Sonnenschein ( now owned by Exide )
>From my experience the AGM  cells are good for instant rapid discharge duty,
but like to be  fully recharged, if not they fall over 100 plus cycles down
the line.
Gels are  better for cycling duty, however both suffer if over charged, both
have same self discharge characteristics which are much better than wet
L.A's
I  use Sonnenschein Dryfit 3 GMF 240  6 volt. TRACTION cells for R.E.
systems when I have doubts about maintenance, they'll give you 1000 cycles
to 80% discharge.
contact for these cells.....Dave Harris   gvanman at ameritech.net
Cheers Clive

PowerSense
Dunnose Head Farm
Falkland Islands
Tel  00 500 42202
Fax 00 500 42203
powersense at horizon.co.fk
http://www.falklandwool.com/powersense
Supply and Installation of 24-hour power systems
----- Original Message -----
From: "Doug Pratt" <dpratt at pacific.net>
To: <RE-wrenches at topica.com>
Sent: Thursday, April 10, 2003 4:22 AM
Subject: RE: Gel Cycle Life [RE-wrenches]


> Hi Travis,
>
>   Real Goods has been selling the MK gels under private label for 5-6
> years. I also seriously questioned those same somewhat amazing cycle
> curves before we took them on. The tests were NOT done by MK, or even by
> the German licensee, Sonenshein (sp?). These were true independent
> third-party tests of random batteries pulled off the assembly line. Get
> MK to cough up the original test results, they're impressive, and so far
> I can tell, totally impartial. (Memory is vague, and I'm writing from
> home without all my hard-copy files, but I think it was NREL decided
> these were the best batteries they'd ever tested.)
>   In the years we've been selling these batteries I've been nothing but
> impressed, with both the batteries and with MK's great service. They've
> bent over backwards warranting batteries that MIGHT have been defective,
> but MIGHT just as well have horribly abused. (Over the phone, everyone
> has treated their batteries like a religious object.) We started out
> telling folks to expect a 2-4 year life. With no (known) failures yet,
> I've upped that estimate to 5-10 years.
>   Hey, you think the smaller batteries have impressive curves? Check out
> the cycle curve on their golf-cart type battery. It went 1000 80% cycles
> and wasn't even fading yet when the tester gave up and shut the test
> off. (Pricey bastard however...)
>
> Cheers,
> Doug Pratt
> Real Goods Technical Editor
>
> -----Original Message-----
> From: Travis Creswell, Ozark Solar [mailto:ozsolar at ipa.net]
> Sent: Wednesday, April 09, 2003 12:34 PM
> To: RE-wrenches
> Subject: Gel Cycle Life [RE-wrenches]
>
> Hello All,
>
> I am looking at using some MK gel batteries on job where maintenance is
> likely to be a problem (and how is that different than any other job?).
> The
> customers seem interested in paying more for no battery maintenance.
> The MK
> batteries are priced very well if you know where to buy them.
>
> It's a weekend hunting camp that's likely to be heavily discharged, 80%
> or
> more DOD, when it's used approximately once per month.  Still, that's
> many
> years according to the factory cycle curve.  And yes, I'm worried about
> charge regulation which makes the NVRAM of the Outback equipment
> especially
> attractive.
>
> The MK Gel battery cycle curve shows
> 2500 cycles @ 25% DOD
> 1100 cycles @ 50% DOD
> 750 cycles @ 75% DOD
> 500 cycles @ 100% DOD
>
> The MK AGM battery cycle curve shows
> 1200 cycles @ 25% DOD
> 500 cycles @ 50% DOD
> 250 cycles @ 75% DOD
> 200 cycles @ 100% DOD
>
> I always thought AGM's were much better cycling batteries than GEL?  The
> GEL
> cycle curve is almost unbelievable.
>
> Anyone else think that GEL cycle curve is way out of line?
>
> Travis Creswell
> Ozark Energy Services
>
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