[RE-wrenches] weak voltage

[Kirpal Khalsa]

Mick.....we had this happen once too.....Luckily it had already become
standard procedure for us to check and notate voltage of each battery prior
to connecting battery cables....we had installed 11 of the 12 batteries and
the 12th battery turned out to have reversed polarity......While we didn't
send it back we made clear markings on the battery case and wired it
appropriately.....Whew!
lesson of the day: always check each battery for voltage and polarity at or
before installation......
OK, now time to go replace a customers battery bank, Note to self:- check
battery polarity!
Be safe, cheers!




-- 
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com


On Mon, Oct 15, 2012 at 6:24 AM, Mick Abraham <mick at abrahamsolar.com> wrote:

> 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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