Mick,
While I fully agree on the importance of a monitor such as the
TriMetric, I'm confused by some of what you've written below. A TriMet
(or any similar monitor for LA) can measure amp-hours removed and
replaced, but it can't measure & display the battery bank's amp-hour
capacity. Only taking the time to drain the bank at a measured rate will
do that, and I have yet to have a customer want to pay me to do a
battery capacity test down to 1.75 vpc at the 20-hour rate - or any rate
for that matter. The TriMet is set up such that the installer tells the
TriMet the battery capacity. In a case such as this, what number would
you program into the TM as the amp-hour capacity? How would you
determine this value?
Thanks, Allan
--
*Allan Sindelar*
al...@sindelarsolar.com <mailto:al...@sindelarsolar.com>
NABCEP Certified PV Installation Professional
New Mexico EE98J Journeyman Electrician
Founder (Retired), Positive Energy, Inc.
*505 780-2738 cell*
On 11/20/2018 11:28 PM, Mick Abraham wrote:
> Hello, Drake & All~
>
> Drake described his service dilemma about batteries bought elsewhere
& whether to correct the original hinky pack wiring (copied below). My
reply below may seem cynical & I may seem too eager to declare the
existing battery as: "Failed". Call me jaded.
>
> Mick's $0.02 is: If there's no amp-hour monitor in the system, I
suggest you first try to persuade the homeowner to buy a metering shunt
& a modest amp-hour meter such as the Tri-Metric--which could be used to
measure & display the battery bank's amp-hour capacity. If the client
won't approve that expenditure (& hourly labor for explanations), the
service tech is hamstrung. Nobody can measure the health of a battery
bank by just looking at it or talking about it...and clients sometimes
receive the inevitable "battery bad news" if they are shown the
diminished capacity on a digital display after an equitably managed
"pump & dump".
>
> Your thought, Drake, of holding back on any re-wiring of the battery
pack...seems prudent...until the first set of amp-hour measurements are
recorded as a baseline. From there...a common pattern is a series of
attempted remediation efforts--all for pay, of course--until the
homeowner acknowledges that it's time to start afresh.
>
> Oops, I left out an important step: getting a read on whether the
client has the money for new batteries or not. I'm personally terrible
at getting that reconnaissance done early enough. If the client isn't
materially blessed to be able to get new batteries, they might be better
off spending limited funds on fuel for the engine generator instead of
on battery testing & tutorials.
>
> Mick Abraham, Proprietor
> www.abrahamsolar.com
>
> ---------- Forwarded message ----------
> From: Drake <drake.chamber...@redwoodalliance.org>
> To: RE-wrenches <re-wrenches@lists.re-wrenches.org>
> Cc:
> Bcc:
> Date: Tue, 20 Nov 2018 11:41:17 -0500
> Subject: [RE-wrenches] Batt Cap AGM
> Hello Wrenches,
>
> An owner of an existing system has a bank of twenty, 100 AH, 12 V
Deep cycle batteries of the Batcap brand.
>
> The bank is made up of four sets of 5 batteries in parallel to
produce 500 AH battery sets at 12 V. These four parallel sets are then
wired in series to give a 48 V nominal bank.
>
> The battery voltages vary from around 13 to 15 volts. The bank is
about 5 years old. The CEO of Batcap told the system owner that these
batteries have lasted up to 30 years in solar applications, so he has
high expectations for these batteries being around for a while.
>
> My first impulse is to rewire the bank in a normal series -
parallel configuration. But there are too many strings to do this
without a bus bar. Besides, the batteries are likely damaged, and
rewiring them might cause the bank to exhibit unsuspected problems. How
much money is worth putting into this bank? $0?
>
> The owner seems like a reliable guy who likely hired the wrong
installer. He could use some help. What would you do in this situation?
Rewire the bank, leave it well enough alone or run for the hills.
>
> Thanks,
>
> Drake
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