[RE-wrenches] weak voltage

[Mick Abraham]

Hello, Wrenchies~

Mac Lewis wrote about battery strangeness on the Sunny Island system for
his clients. Here is a theory to consider, Mac.

I once bought a 48v string of >famous brand< two volt cells in which one
cell had been loaded backwards into its case. When hooked up according to
the +/- markings on the case, this cell was discharging at the same time
the rest of the string was charging so even though the others were running
high during the charge, the end to end voltage immediately slumped to
relatively low values after the charge was ended. The one cell was
effectively missing in action.

My client was a DIY type who was distant from my location but he owned a
voltmeter that was still in the box. I coached him through a "voltage walk"
up the string and sure enough we found the one increment that was
subtracting from overall string voltage instead of adding to it. The
>famous< battery supplier said this was impossible, they are checked three
times, this never happens & can't happen, blah blah...and they were only
convinced when the cell was back in their shop and they could measure this
for themselves.

Even after they checked it, they said, "It's the first time in our 20 +
years with that brand that we have ever seen this." Black swan.

At my request, the company paid to ship back the entire string and ship all
new replacement cells to the client. This seemed important because the
other 23 cells had been subjected to a high voltage per cell and had gotten
a bit hot before the problem was discovered.

++++++++++++++++++++++++++++

Perhaps this theory is worth checking on site. Whatever you find to resolve
this problem, Mac, be sure to report back on list so we can all learn.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com

Voice: 970-731-4675
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