[RE-wrenches] Tri-Star MPPT

Tue Jul 23 14:48:55 PDT 2013

Hi William,

 If the SG was 1.26, of course the battery voltage would increase 
quickly to >30V (which is high for warm weather, BTW).
 It has been my experience that sulfation causes the voltage NOT to climb. 
Especially when you have a very large bank, and a
 relatively small amount of solar.
 Sometimes it is necessary to reduce the bank size into smaller sets to 
equalize them and recover their performance.
This method of reducing bank size is also effective to compare performance 
and weed out a potentially bad battery. 
 Systems that have a lot of capacity, with a relatively small amount of 
charge current usually creates problems, because
 the load demand exceeds solar production.
 This results in batteries that operate with partial SOC, which is when 
sulfation is most prevalent. With (8) L16s, you have approx
 800Ahrs of capacity (24V bank). It would take significantly more than 8A 
of charge current to properly care for a bank that size.

Rgds,
_____________________________________________________________________________________ 

Eric Bentsen  |   Schneider Electric   |  Solar Business  |   UNITED 
STATES  |   Technical Support Representative 
Phone: +(650) 351-8237 ext. 001#  |   
Email: eric.bentsen at schneider-electric.com  |   Site: 
www.schneider-electric.com/solar  |   Address: 250 South Vasco Rd., 
Livermore, CA 94551 

*** Please consider the environment before printing this e-mail 

From:
"William Miller" <william at millersolar.com>
To:
"RE-wrenches" <re-wrenches at lists.re-wrenches.org>
Date:
07/23/2013 01:13 PM
Subject:
[RE-wrenches] Tri-Star MPPT
Sent by:
re-wrenches-bounces at lists.re-wrenches.org

Friends:

I have a customer with a new Tristar MPPT controller.  The customer has 
some older L-16 batteries mixed with new and she thinks the controller has 
damaged her batteries.  I am trying to convince her that the batteries 
were already damaged and mixing old with new is a bad idea.

I removed the worst batteries from the array, leaving one string of older 
batteries with reasonable SG readings.  The CC still acts strangely:  When 
programmed to charge the L-16 batteries, the battery voltage shoots up to 
30.2 volts and the batteries boil a lot.  The green light on the 
controller blinks at variable rates, at one moment fast, the next slow, 
the next solid.

I believe the client started with bad batteries, 6 are 4 years old, 2 are 
1 year old.  She is convinced that the CC damaged her batteries.  She 
replaced panels and CC recently, installing the Tristar.  I believe the 
old PV system charged at such a slow rate (8 amps) that the battery 
deficiency was not apparent.  The higher charging rate has emphasized the 
problem.

Any one have any thing to add to my theory?

Thanks in advance.

William Miller

17395 Oak Rd. Atascadero, CA 93422
www.millersolar.com
805-438-5600 voice*
*Note: above number replaces cell number

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