When I'm evaluating an old system, one thing I do is really yank on all
the battery connections. If it turns, tighten it down, and in several
cases, the cable just pulls loose from the connector. They are time
consuming to do right. Cable has to be stripped long enough, the
crimper needs to be set correctly, and be the right crimper for the
particular lug.
Below is an example of:
the wrong cable (THHN, not X Flex)
Not enough cable stripped
Wrong Size Lug
Not Crimped Properly
Not Vaselined
Now let's put 150 amps continuous through that garbage and see if we
have some long term issues......
R.Ray Walters
CTO, Solarray, Inc
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 1/21/2017 3:16 PM, Dan Fink wrote:
Last weekend. 3-year old, 24v battery bank, series/parallel.
6v Trojan L-16 in an 8-battery bank, one battery on one string showing
4v. Negative end of string. Replaced the one upstream of it last
summer, same problem. Aha! I say, and folks here on the Wrenches list
(including me) complaining about Trojan cell failures, factory defects
(I've had one too) and that the battery on the negative end fails
first. Darn you Trojan. Up your game.
3yr - 3yr - 3yr - 3yr
4v - new - bubbling - 3yr
So as I am disconnecting this string so the homeowner has at least
half a battery bank, I can hear the next battery upstream of the NEW
one bubbling, with no power in or out, system shut down. Didn't need
the thermal imager this time, we could feel it was hot.
And, as we are doing this disconnect and pulling off interconnects,
the cable between the 4v battery and the new one pulled right out of
the ring terminal lug. Bad crimp. Cause of problem now known. These
were factory interconnects purchased from AltEDirect.com.
Never again...I have the tools to make up interconnects and do it on
small projects, it's just they are so time consuming to do right
(crimper, glue-melt heat shrink, etc) that it costs me more in labor
(unless I have student interns working for free) than buying them from
AltE.
That crappy crimp cost my customer 3 Trojan L-16s. I have notified
AltE. They should be ashamed.
I believe it was Mr. Tom Duffy, SolarBiz, on this list who pointed out
during the Trojan thread that cell failures were rare, most failures
are due bad connections. I've had a real cell failure (Trojan J185)
but in this case, Mr. Duffy was spot-on.
Best regards;
Dan Fink
Adjunct Professor of Solar Energy Technology, Ecotech Institute
IREC Certified Instructor™ for:
~ PV Installation Professional
~ Small Wind Installer
Executive Director, Buckville Energy
NABCEP Registered Continuing Education Providers™
970.672.4342 <tel:970.672.4342>
On Sat, Jan 21, 2017 at 7:54 AM, cwarfel
<cwar...@entech-engineering.com
<mailto:cwar...@entech-engineering.com>> wrote:
Hi David, do you have any pictures of this that could be shared?
Chris
On 1/20/2017 12:52 PM, Dave Palumbo wrote:
Following is an entry from a Backwoods Solar email that I
received today. I would like to share this as a teachable point
for RE techs not familiar enough with proper battery bank care
and as a reminder for those of us with years of storage battery
experience.
I have underlined the two issues in the Backwoods email copied
below my bullet points to highlight the teachable issues.
·Checking wiring connections: Check not only for tightness but
also for temperature. There are two simple methods that work
well: #1) Use an IR Thermometer to ensure all connections are of
a similar moderate temperature. #2) Use your fingers to check
temperatures. I'm practiced at this second method because
inexpensive IR thermometers were not available when I began to
care for storage batteries. I simply use my bare fingers (with a
light coating of petroleum jelly) to wiggle test each battery
cable at the battery terminal. Fingers are sensitive enough to
gauge proper temperature. I have easily found several warm or hot
connection points over the years caused by loose or corroded
hardware. Do this as preventive maintenance every time you water
the batteries or bi-monthly with sealed cells. Corrective
measures (tightening, or taking apart and cleaning, or replacing,
and reinstalling) are taken immediately when a warmer than usual
connection is identified.
·It is not recommended by most veteran wrenches to use any
"anti-corrosion paste" on the terminal connections. This has been
discussed a few times over the years on the Wrenches list. Most
of us have found that a thin coating of petroleum jelly (Vaseline
is one brand) does the best job of protecting against corrosion
while still allowing some visual inspection.
from Backwoods Solar 1/20/17. << This past summer Backwoods had
a visit from one of our retired co-workers, xxxxx. While it is
always good to have friends visit, the circumstances for his
dropping by were less than ideal.
A small, catastrophic failure had led to the loss of a battery
bank, two inverters, and a voltage converter. Ultimately, the
failure was traced back to a single nut and bolt in the battery
bank cable connections, that had developed hidden corrosion over
time. Corrosion causes resistance to the flow of electricity,
which in turn generates heat. With enough corrosion, and enough
current flow, the amount of heat generated can be sufficient to
melt battery terminal connections; which is exactly what happened
in xxxxx’s case. The melted metal flowed between the negative and
positive terminals of his industrial battery, causing a high
power short that was beyond the capabilities of any of the
circuit protection, resulting in the damage to the equipment.
Now keep in mind, xxxxx is one of the more detail-oriented people
we’ve had here at Backwoods. The discipline of a military
background, along with critical thinking of an engineer, were
still not enough to overlook one very tiny detail. xxxxx does
his mechanical maintenance on a routine schedule; _checking for
tightness in wiring connections_, cleaning accumulated spray off
battery tops, cleaning out dust and spider webs, _and keeping his
battery terminal posts coated with anti-corrosion paste._ This
is not the type of person you’d expect to see such a failure.
So what happened? It all boiled down to the battery terminal
connections. What xxxxx had NOT done, was dissembled the nut and
bolts from the battery terminals and cables to check for
internal, hidden corrosion. It had been about 6 years since he
had done that level of inspection. When previously reviewed, the
hardware had been thoroughly inspected, cleaned, and
re-assembled, and then coated with _anti-corrosion paste on the
exterior_. In one of the 16 nut/bolt pairs, a small bit of
contamination or moisture must have been left trapped inside.
Over the course of the next six years, the corrosion grew,
contaminating the entire connection; but was NOT visible
externally at all! >>
Best regards,
Dave
David Palumbo
Independent Power LLC
462 Solar Way Drive
Hyde Park, VT 05655
802-371-8678 <tel:%28802%29%20371-8678> cell
802-888-4917 <tel:%28802%29%20888-4917> home
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