[RE-wrenches] Hidden corrosion caused catastrophic battery system failure

Sat Jan 21 14:16:48 PST 2017

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

On Sat, Jan 21, 2017 at 7:54 AM, cwarfel <cwarfel at 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 <(802)%20371-8678> cell
>
> 802-888-4917 <(802)%20888-4917> home
>
>
>
>
>
>
>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html
>
> List rules & etiquette:www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:www.members.re-wrenches.org
>
>
> --
> Christopher Warfel, PE
> Entech Engineering, Inc.401-466-8978 <(401)%20466-8978>
>
>
> _______________________________________________
> List sponsored by Redwood Alliance
>
> List Address: RE-wrenches at lists.re-wrenches.org
>
> Change listserver email address & settings:
> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org
>
> List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.or
> g/maillist.html
>
> List rules & etiquette:
> www.re-wrenches.org/etiquette.htm
>
> Check out or update participant bios:
> www.members.re-wrenches.org
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20170121/759d436d/attachment-0002.html>