Battery Experience/Suggestions for Grid Tie? [RE-wrenches]

Roy Butler, Four Winds RE roy at four-winds-energy.com
Thu May 24 12:03:27 PDT 2007


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Matt,

This post will probably wind up in electron limbo...but here goes...

I have a bunch of Edison NiFe cells...made between 1932 and 1940 that 
Bob Ellison and I took off of a steam train in Virginia.
Some had been in continuous for a lot of years on the train and now 20 
of these form a 24 volt bank I use here in the shop.

Others from this same group had been discharged, shorted with jumpers 
and stored for about 20 years.
These are working quite well....accepting a charge and load testing to 
70-75% of their rated capacity.
As with the NiCads, the Edison manual says to change the electrolyte if 
the capacities drop over the years.

75 years and counting.....I'm thoroughly impressed!

Roy Butler
NABCEP Certified Solar PV Installer®
NYSERDA eligible PV & wind installer 
Four Winds Renewable Energy, LLC
8902 Route 46
Arkport, NY 14807
607-324-9747
www.four-winds-energy.com

Although no trees were killed in the sending of this message, 
a large number of electrons were terribly inconvenienced.




Matt Tritt wrote:

>
>
> It's hard to bead NiCads for longevity and robustness. I know someone 
> who has lived off-grid on a farm back East with a pair of small wind 
> turbines (Dunlite and a Swiss machine) for many years with a NiCad 
> bank from the 50's. This has to be some kind of record! They told me 
> that "all you have to do is replace the electrolyte every 10 or 20 
> years, and you're good to go. Jeeze Louize!
>
> Matt T
>
> Todd Cory, Mt. Shasta Energy Services wrote:
>
>> That is another advantage of lead calcium wet cells. They use next to 
>> no water. In the 20 years the bank I inherited were at our hydro 
>> plant, they had water added only twice. Equalizing is not recommended 
>> more than ever few years (if ever) either. They are robust and not 
>> easily damaged. They last a very long time and are specifically 
>> designed for float conditions. The only downside is the cost.
>> The price to replace those lead calcium wet cells down at the dam was
>> around $10K for 12 kW (20 X 6 volts X 100 a/h). By comparison 20 kW of
>> L-16's were at the time about $1.3K. And that is for about twice the 
>> a/h's. The life span is about 1/3 but still, even considering that 
>> the price differential is about 10X!!
>>
>> If you have a customer that tends to not pay close attention to the 
>> batteries in their backup system, AND price was not an issue... these 
>> are the cells I would choose.
>>
>> Todd
>>
>>
>>
>> Doug Pratt wrote:
>>  
>>
>>> Hey Travis. Grid tie and wet-cell batteries are not usually a happy 
>>> combo.
>>> Two primary problems. 1. Customers forget to service (water) them. I've
>>> never visited a grid-tied wet-cell battery pack without finding exposed
>>> plates. It's just too easy to forget them. 2. All the common deep-cycle
>>> wet-cell batteries on the market (T-105's, L-16's, Rolls-Surrette, and
>>> Hawker) expect to be used and cycled regularly. Their chemistry 
>>> isn't built
>>> for long, long periods of float charging. Think of them like the 
>>> muscles of
>>> your body. They need modest amounts of regular exercise to stay 
>>> healthy.
>>> Don't go to wet cells with grid-tie unless they're specially 
>>> constructed for
>>> emergency backup service, and you do some kind of automatic (or very 
>>> easy
>>> semi-automatic) watering system.
>>>
>>> Sealed batteries are usually expected to go into emergency backup 
>>> service,
>>> their chemistry is tweaked a bit so they're happier doing long 
>>> stretches of
>>> float service without becoming hopeless weaklings. AGM sealed types are
>>> easier to build (and therefore usually cheaper...Concorde's excepted,
>>> especially the past couple years!), but they're fluid starved so 
>>> have little
>>> tolerance for even the least overcharging. Gel sealed types are 
>>> trickier to
>>> build, but start out with greater fluid reserves, so they're a bit more
>>> tolerant of the occasional overcharge. Gels will usually last 10% to 
>>> 15%
>>> longer than AGMs.
>>>
>>> I've been selling the MK Gels (made by Deka I believe) for over a 
>>> decade.
>>> Service life is roughly 5 to 10 years. It depends a lot on the 
>>> customer's
>>> use and charging patterns. Set your charging voltages no higher than 
>>> 2.35
>>> volts per cell with sealed batteries. NO equalizing!
>>> Oh God! I've ventured into BATTERIES! A world with no black or white 
>>> but
>>> plenty of gray areas. Let the flames begin... (got my nomex shorts on).
>>>
>>> Cheers,
>>> Doug Pratt
>>> DC Power Systems
>>>
>>>
>>> -----Original Message-----
>>> From: Travis Creswell [mailto:tcreswell at ozarkenergyservices.com] 
>>> Sent: Wednesday, May 23, 2007 7:23 AM
>>>
>>> Hello All,
>>>
>>> We've got several grid tie customers with aging or dead Concorde AGM 
>>> battery
>>> banks.  They feel that they got pretty poor calendar (4-6 years) 
>>> life from
>>> these batteries and the customers are not that excited about going 
>>> back with
>>> another ~5 year battery bank.  We did about 20 systems in 1999 with
>>> Concordes and only one of them is still alive.  All in all we 
>>> weren't that
>>> impressed with Concordes.  How have MK AGMS been doing for folks?  
>>> We've got
>>> a few really small sets out there
>>>
>>> Both of these customers have budgets and I think would tolerate 
>>> paying more
>>> for batteries in exchange for getting a longed life battery bank.  Both
>>> banks are in the basement but with some construction we could 
>>> construct a
>>> venting system so flooded batteries are not out of the question.  
>>> But I'm
>>> not sure either of these customers would properly maintain flooded
>>> batteries.
>>>
>>> So what batteries should I be looking at?  I'm pretty sure we need 
>>> to just
>>> skip right past T-105 and L-16.  What about the HUP or similar in float
>>> service?  One customer has several multi day power outages 
>>> annually.  The
>>> other rarely looses power for more then a few hours a year.
>>>
>>> I'll look forward to suggestions.
>>>
>>> Regards,
>>>
>>> Travis Creswell
>>>
>>> Ozark Energy Services
>>>
>>>
>>>
>>>
>>>
>>>
>>>   
>>
>>
>>
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