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

[Jerry Shafer]

Wrenches
I have been around batteries for many years and I have had poor battery
construction issues and installation issues but in most cases, failures can
be avoided by visual inspections and not the fire and forget that so many
people that think maintenance free means. The trogan pic is a result of a
over heated terminal as the plastic will not corrode but instead melt,
loose connection resulting from improper crimp, gauge of wire, over/under
torg of the terminal being the most common, not crimped is not a common
problem. Over torq of the stud will crack the lead and result in failure
down the road, under torq happens sooner and may just cause an open in the
circuit or god forbid a spark, both are installer issues not battery
manufactures. Over-filling of batteries attempting to reduce service
intervals is another common issue on flooded batteries and will boil over
of acid all over and a diluted SG both reducing the life of the battery
again not a manufacturing issue. Something that is commonly missed, is all
the cable must be at rest when installed and not under a sprung load, this
will prevent terminal moving as result, again causing a failure and
possible spark under the right conditions. Something that l did that I
think increased the life of my batteries was to rotate position in the 48
volt arrays. I did large scale events off grid and had individual volt
meters on each battery and at times there was an imbalance which rotating
corrected. because of the nature of what I did l would push the 48 volt
system to 38 volts before the LVD would shut me down (Gennys were in most
cases not wanted due to the smell and noise). Even with the hard cycling
along with being mobile, I would see 6 to 7 years out of my 8-D's and
L-16's.
FYI,  for who ever services FLA batteries get a one gallon weed sprayer,
label it for distilled water only, cut the nozzle tip off and you have a
easy watering system for your batteries.
Jerry

On Sat, Jan 21, 2017 at 5:58 AM, cwarfel <cwarfel at entech-engineering.com>
wrote:

> Thanks Dave, This is all helpful. We do 90% battery systems, and I need
> to emphasize periodic maintenance. This will help.  Chris
>
> On 1/21/2017 10:52 AM, Dave Palumbo wrote:
>
> Hi Chris,
>
>
>
> I don't have any pictures myself, the Backwoods email included a photo of
> a corroded bolt and a clean assembly which I've snipped and attached.
>
>
>
> Off the Wrenches list I have had a conversation with another wrench who
> shared his successful methods which I will share here.
>
>
>
> << The issue I remember from before on this thread was do you put the
> material between the lug and post or outside of it?
>
> And I’m not sure from the article if it was put on between or outside?
>
>
>
> Personally I’ve done between and  never had a problem. Yes I’ve seen
> corrosion around the lug, but take the lug off and its clean.   Outside
> seals the corrosion in, inside prevents it from forming IMO.
>
>
>
> However, if the bolt got lose, it would generate heat, which would melt
> out any and all material, creating oxidation, more heat and away you go to
> failure mode.
>
>
>
> Also the photo doesn’t show split/lock washer.  I think its really
> important as the lead does flow over time, so no matter how tight you make
> it,  it will loosen up over time especially with higher currents/heat.
>
> The lock washer will buy you some time before needing to retorque the
> fasteners.
>
>
>
>  I’m curious about the damage mode to the inverter and all that.  I don’t
> understand how a short on the battery would destroy all the electronics?
>
>
>
> I’ve gone to a battery angle grinder with flappy wheel to prep the
> terminal posts. - fast. >>
>
>
>
> My response to him.
>
> I wondered about the failure of those big expensive components too, but I
> have never had a dead short for more than a split second at the batteries
> (a few misplaced cables when working too quickly are easily dealt with). I
> have been installing a catastrophic class T fuse between the battery bank
> and the DC distribution center breaker also.
>
>
>
> I would always buff the cable ends with a green scrubbie and file the
> battery terminals to remove any corrosion and then lightly coat all
> surfaces,  including all the hardware thoroughly (incldng lock washer),
> with petroleum jelly before assembling and tightening (very tight - tight
> as I could without breaking the hardware, lead starts to compress). I've
> been very happy with doing it this way for 30+ years. Learned much of this
> from Peter Talmage and Rob Wills here back east as well as from Richard
> Perez (RIP).
>
>  Dave
>
>
>
>
>
> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org
> <re-wrenches-bounces at lists.re-wrenches.org>] *On Behalf Of *cwarfel
> *Sent:* Saturday, January 21, 2017 9:54 AM
> *To:* re-wrenches at lists.re-wrenches.org
> *Subject:* Re: [RE-wrenches] Hidden corrosion caused catastrophic battery
> system failure
>
>
>
> 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
>
>
>
>
>
>
>
>
>
>
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> --
>
> Christopher Warfel, PE
>
> Entech Engineering, Inc.
>
> 401-466-8978 <(401)%20466-8978>
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> --
> Christopher Warfel, PE
> Entech Engineering, Inc.401-466-8978 <(401)%20466-8978>
>
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