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

[Matt Tritt]

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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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