[RE-wrenches] intermittent battery problem; The Last Word

Tue Nov 22 09:26:00 PST 2011

I have a question.  The specific gravity is an indicator of the 
concentration of the sulphuric acid in the cell as I understand it. 
If the SG is very high (as reported) then the sulphate ions must be 
mostly in the electrolyte and not on the plates.  This makes me ask, 
how can it be that the plates are sulphated with high SG? (sorry for 
my quaint olde worlde spelling)

Another thing I would ask is why not give the customer a $10 
multimeter and instructions how to check each battery ("press hard 
with the tip of the probe" etc).  Then when the voltage plunges down, 
and before recharging, ask them to check each battery with this 
meter?  That would identify or rule out the intermittent internal 
resistance theory.  If it exists, it's just in one battery. 
Presumably.

Hugh

>Larry, the customer has been fully charging and equalizing every 
>week to two weeks for several years. They also are diligent about 
>checking the batteries with a hydrometer. It turns out then that I, 
>and the customer, have put too much faith in hydrometer readings to 
>give an accurate picture of battery health? Yes I agree (long time 
>ago) the battery monitor would have been helpful in catching the 
>problem - if this is the problem. A couple of other posters have 
>suggested another possibility: a fractured bus bar inside the 
>battery or a dead cell. Both of these suggestions came from people 
>who experienced almost identical problems that were extremely 
>difficult to detect. I have recovered several sets of sulphated 
>batteries, Surrettes, Trojans, Yuasa, so I know what they are like 
>and what they smell like when subjected to a high amp charge.
>
>I have several sets of these KS25's & 21's in the field and for the 
>most part they have worked very well but I've seen customers 
>sulphate L-16's in a few weeks of deficit charging, it just takes 
>longer with a big battery especially when they aren't really being 
>abused.
>
>I'm sure hoping the horse hasn't left the barn on this one.
>
>Ron Young
>
>On 2011-11-17, at 12:32 PM, Larry Crutcher, Starlight Solar Power 
>Systems wrote:
>
>>  Ron,
>>
>>  From what Daryl said below and the fact that your customer has 
>>about 15 amps of PV charge, you should deduct that the batteries 
>>have MOSTLY been deficit charged their entire life.  Here's what I 
>>told you on Oct 22 in my lengthy explanation about what the problem 
>>is and why it happened: "Undersized RE charging systems, or perhaps 
>>oversized batteries, is the culprit that contributes to this all 
>>too frequent phenomenon of chronic undercharging."
>>
>>  You said that the customer has been compensating for an undersized 
>>system by running a generator. They can not know this because there 
>>is no monitor. The batteries now have a sulfation problem, perhaps 
>>unrecoverable, that could have been prevented if the owner had a 
>>battery capacity monitor. This is not pleasant news, I know. I have 
>>to explain this bad news to people MANY times each week. This is a 
>>huge issue globally. And such waste of money, time and resources 
>>just bugs me!
>>
>>  Larry Crutcher
>>  Barer of Bad News
>>  Starlight Solar Power Systems
>>
>>  On Nov 17, 2011, at 5:17 AM, penobscotsolar at midmaine.com wrote:
>>
>>>  Ron,
>>>   I'm going to reiterate what Jeff says here. It is similar to what I had
>>>  said in my email. The charge rate must REGULARLY be C10 on the KS
>>>  (5000 series) batteries. This means, on KS 25's, a routine bulk
>>>  charging rate of 135 amps. I find that on these types of hybrid
>>>  systems, while the batteries might occasionally (sunny day, generator
>>>  running, etc.) that kind of charging, they do not regularly see C10. I
>>>  think if you gave Jamie Surrette a call he would give you the same
>>>  possible assessment.
>>>   I do think the problem is oversulfation, but none of this solves your
>>>  problem, I know. We have been installing KS series batteries since they
>>>  came out and this necessity of regular C10 charging has been an
>>>  integral  part of design for me for many years.
>  >>
>>>  Best,
>>>  Daryl
>>>
>>>
>>>
>>>
>>>>  Ron,
>>>>
>>>>
>>>>
>>>>  This reply a little late since I have been off line a few days.  I
>>>>  mentioned
>>>>  in a similar thread last year that I had an off grid home client I
>>>>  designed
>>>>  and installed in Idaho back in 1998 that had a Kohler 8.5 kw generator, a
>>>>  Trace 4024 inverter, two separate solar arrays and Outback charge
>>>>  controllers, and 16 Trojan "L-16" batteries.  This system worked
>>>>  flawlessly
>>>>  for 7 years and only required the generator a few hours per month, then it
>>>>  was time to change the batteries.  I replaced the Trojans with the same
>>>>  size
>>>>  battery made by Surrette and everything went to crap.  They had to run the
>>>>  generator hours and hours to get them past an 80% charge and we had lots
>>>>  of
>>>>  problems with overloading the generator even though we did not make any
>>>>  program changes and used the same generator.  The generator was replaced 2
>>>>  years later but this system  never worked like it did before the battery
>>>>  replacement.
>>>>
>>>>
>>>>
>>>>  When researching all this at that time I had talked with Surrette, Trojan,
>>>>  and anyone else that might help and this is what I found out.  Of course
>>>>  there are just my opinions based on these conversations, but it is my
>>>>  understanding that Surrette is a much longer life battery with much less
>>>>  water loss when comparing apples and apples, and I was told this was due
>>>>  to
>>>>  a different lead composition that Surrette uses than any other battery
>>>>  manufacturer.  However, this difference requires a much longer
>>>>  absorption/taper off charge process or you will never get it past 80%
>>>>  charged.  This of course is almost impossible to achieve with a generator
>>>>  or
>>>>  undersized solar array, and you really need a grid connection to fully
>>>>  charge these things.  No doubt these would be great in some standby grid
>>>>  connected system but I no longer use them in off grid.  This was also at a
>>>>  time when battery manufacturers were just discovering solar so maybe
>>>>  battery
>>>>  designs have changed.  Again, I think Surrette is a good company and makes
>>>>  a
>>>>  great battery, but just not sure you can fully recharge them with a
>>>>  mid-sized generator.
>>>>
>>>>
>>>>
>>>>  I also do not like using parallel battery layouts as its hard to keep one
>>>>  string from pulling down the other strings when there is a low performance
>>>>  cell so you might do a cell by cell check.
>>>>
>>>>
>>>>
>>>>  Good Luck,
>>>>
>>>>
>>>>
>>>>  Jeff Yago
>>>>
>>>>  DTI Solar Inc.
>>
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-- 
Hugh Piggott

Scoraig
http://www.scoraigwind.co.uk