Mysterious Surrette Behavior (was: More on battery management) [RE-wrenches]

Travis Creswell, Ozark Solar ozsolar at ipa.net
Thu May 11 06:59:51 PDT 2006


Hello Rob,

Something similar happened to me with some new 1400 AH Surrette KS series
batteries several years ago. (one string @ 24 volts)  The TriMetric would
tell us that the batteries were full but the SG would be way down there.
Sorry I can't remember specifics.

I'll skip past all the things we tried (per Surrette suggestions) with no
result but it turns out the Surrette KS really needs to be charged with a
lot amps regularly.  Way harder then most any off grid array could charge
them. Which they admitted only after I explained to them that I wanted to
return these batteries since the SG continued to stay low regardless of what
we tried.  Turns out they are really fork lift plates in cases that say
"solar".  If you followed Surrettes recommendations your battery couldn't be
larger then one day of solar charging and that might to big.  I explained to
them that my generator powered battery charger was capable of over 200 amps
(2 x SW4024) they told me that was a little light.  They offered no
explanation why they marketed them as "solar batteries".

Thankfully the customer could afford to increase the size of the array by
50% (from 1kW to 1.5 kW) and that seemed to solve the problem but probably
just barely.  I'm up there every 6 months or so and things are going fine so
far.  We have the absorption time on the MX60 set to 4hrs and the voltage
set to 29.6.  As the batteries age the array will probably be too small
again.

So what I theorize is happening with your batteries is they aren't being
charged hard enough.  How large is the array?

Best,

Travis Creswell
Ozark Energy Services


-----Original Message-----
From: Jay Peltz, Peltz Power [mailto:jay at asis.com] 
Sent: Thursday, May 11, 2006 12:17 AM
To: RE-wrenches at topica.com
Subject: Re: Low electrolyte levels (was: More on battery management)
[RE-wrenches [RE-w


HI Rob,

I have seen more battery mysteries with Surrette's than any other  
battery.

I  have seen lots of batteries that don't seem to hold charge, won't  
come up to charge, etc.

I know that the common fix's, and tests that work with other  
batteries just dont seem to do the same thing with Surrettes'

jay

Peltz Power


On May 10, 2006, at 11:09 PM, Rob Harlan wrote:

>
> Windy and Company
>
> We have been scratching our heads over a particular battery mystery:
> It is an installation with eight new (now 4 months old) Surrette  
> 530AH 6V
> in 24V config.
> We first were alerted that the Trimetric state of charge readings were
> consistently sustantially over optimistic in relation to both  
> voltage and
> specific gravity data. This had resulted in maybe 3-4 weeks during  
> which the
> batteries stayed at pretty reduced charge levels.  The specific  
> gravity
> readings at this point showed a .020 spread between cells.
> Since these were new batteries we suspected the Trimetric or the  
> wiring.  We
> proceeded to verify Trimetric settings as well as voltage and amperage
> calibration (all OK), tighten all connections to the shunt, verify  
> that all
> amperage in and out was passing through the shunt, and insure that  
> the owner
> was bringing the batteries to 100% State of Charge ( based on 29.2V  
> and 10
> amps) every 5-10 days so the Trimetric has the opportunity to  
> recalibrate
> itself. We also installed a second Trimetric closer to the  
> batteries to
> provide comparative data (identical). At this point we don't think  
> it is the
> Trimetric.
> Upon discovering the undercharged batteries with a 20 point sg  
> spread we
> assumed a sulfated condition and
> initiated a generator-driven corrective equilization charge  
> (bringing the sg
> to 1.265 and holding the
> batteries there for three  hours).  This resulted in a reduction of  
> the cell
> spread to
> .013.
> The next two and a half months consistently showed:
>     1) Very inacurrate Trimetric state of charge readings (still
> optimistic).
>     2) A variance of 10 to 40 points in cell sg numbers.
> During that 21/2 months we carried out two more equilization  
> charges. The 40
> pt spread has ocurred most recently.
> SG readings are being taken with a refractometer which, by the way,  
> we find
> to be far easier to use than a hydrometer (order from
> http://www.misco.com/traditional-hand-refractometer.html Glycol and  
> Battery
> Tester $135 part # 7084VP+)
> The spread in cell readings do not reveal one outstandingly bad cell.
> Unfortunately baseline specific gravity readings were not taken at
> installation.  We have not been physically stirring the electrolyte  
> before
> taking refractometer readings. The other possibly pertinent  
> information is
> that the cells were slightly overfilled at installation with some  
> degree
> of electrolyte (probably not a lot lost during early charging cycles.
>
> Can these symptoms be indicative of  a a low acid condition?    
> Wouldn't a
> low acid condition prevent the sg readings from reaching 1.270?   
> How does
> one determine electrolyte pH? Can a loss in electrolyte cause these
> symptoms? Any other thoughts on this chronic wierdness?
> Thanks in advance for this whole battery discussion and I look  
> forward to
> Windy's article.
>
> Rob Harlan
> Harlan Electric
> NABCEP Certified
>


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