Did you look for dead cells? I've seen many L 16 sets (including my
own) only last 4-1/2 years, so that set was already almost done. If she
started mixing new batteries in before, she knew she already had a
problem. Did this system change from 12 v to 24 v? The rule of thumb
for eons (or at least the long history of lead acid batteries) is that
a mixed set of new and old batteries will only last as long as the
oldest battery. The new batteries will be chronically undercharged,
while the old ones will be chronically over charged.
My guess is the higher charging rate available caused some already
heavily sulfated cells to go ahead and short out.
It's like giving a gasping man some oxygen, and then he goes into
cardiac arrest. You did what you could, but those batteries were on
their way out already.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 7/23/2013 3:36 PM, William wrote:
Brian:
I don't have the PV details handy but I will provide them.
Question: will a sulfated cell exhibit a SG of 1.26? I thought a
sulfated cell locked the acid onto the plates, minimizing the SG
readings below that of a healthy cell. 1.26 is a relatively high reading.
William
On Jul 23, 2013, at 1:28 PM, Brian Teitelbaum
<bteitelb...@aeesolar.com <mailto:bteitelb...@aeesolar.com>> wrote:
William,
What does the PV array consist of? What size and type, and how many,
modules?
Which TriStar? 45 or 60A?
What controller did she have before the upgrade?
The high charging voltage might be a sign of sulfation. Depending on
her load profile, that 8A charge rate might have caused chronic
undercharging. In a 5 peak sun-hour location, that's only 40Ah/day of
charging capacity.
Brian Teitelbaum
AEE Solar
*From:*re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*William Miller
*Sent:* Tuesday, July 23, 2013 1:13 PM
*To:* RE-wrenches
*Subject:* [RE-wrenches] Tri-Star MPPT
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
<image002.jpg>
17395 Oak Rd. Atascadero, CA 93422
www.millersolar.com <http://www.millersolar.com/>
805-438-5600 voice*
*Note: above number replaces cell number
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