Mysterious Surrette Behavior [RE-wrenches]

Fri May 12 13:55:14 PDT 2006

Hi,

I'd like to add some general comments about big batteries and off grid
systems. I've had occasions to discuss the matter of oversized batteries (or
undersized charging systems) with a few battery manufacturers. They have
been consistent in telling me that the ability to apply significant amounts
of minimum current to batteries is key to successfully charging them. As a
general rule of thumb they specify a minimum of the C10 rate for initial
(max bulk amps) charge rate and C5 if you can perhaps deliver it. In my
various jobs over the last twenty years I've also had the opportunity to see
countless battery systems which were oversized for the available charging
system, a very high percentage underperformed with respect to longevity
expectations. I think the battery manufacturers are correct in demanding
high capacity charging systems for their large batteries - especially those
offering long warranties. 

I've lived with large capacity batteries for years (the same set for the
last fourteen) and I can attest that the only time I really get them fully
charged from renewable is on those bright sunny days when the wind is
howling as well - I can get pretty close to the C10 rate of my batteries in
those conditions and they respond very nicely to the extra charge current.
I've even been known to start the generator early in one of these perfect
weather charge cycles to add an extra 80 amps or so to the initial rate.

Bottom line for me is that battery charging is a lot like cooking. Bring the
electrolyte up to temperature with current and the magic transformation of
water into acid occurs. Without sufficient current the electrolyte never
gets sufficiently warm for a full charge process to occur and the batteries
remain essentially "under cooked". I often compare battery charging to
cooking a pot of pasta. You can put the pasta in a pot of cold water and
leave it on the stove on low all day. At the end of the day you'll have
tepid mush but it won't be cooked pasta. You need to apply sufficient heat
to boil the water to cook the darn stuff, much like you have to apply
sufficient current to charge the batteries.

Best regards,

Ezra

Ezra Auerbach
DragonSun Consulting 
Morewater Road 
Lasqueti Island, B.C. V0R 2J0

Tel 250.333.8650
Email: ezra at lincsat.com

-----Original Message-----
From: Ray Walters [mailto:walters at taosnet.com] 
Sent: Friday, May 12, 2006 9:18 AM
To: RE-wrenches at topica.com
Subject: Re: Mysterious Surrette Behavior [RE-wrenches]

Travis, Rob, Dave, & All;

An interesting thread, considering I returned last night after 
installing a new set of Rolls Series 5000s to have the inverter shut off 
as soon as I plugged my sawzall in to the customer's new system. 1 cell 
was completely Dead (0 volts) and since I've been moving to single 
strings to avoid paralleling, the system is inoperable. So what is the 
current word on Rolls? I'm beginning to wonder, after reading everyones' 
experiences with them.
What is a better battery? I sold Bulldogs and Exides before, and those 
were all fork lift batteries without apologies. I found the Rolls easier 
to install, and easier to get cycle life data on. I'm sure not going 
back to L16s.

Ray
Solarray.com

>  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".
>
>
>Travis Creswell
>Ozark Energy Services
>
>
>  
>

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