[RE-wrenches] Sick pack

Thu Dec 19 12:02:19 PST 2013

Bill

With 4 parallel strings at 6 years you surely will have some bad cells. I would let the bank sit (with no load or charge) for at least 8 hours, or if you can 24 hours and simply do a voltage check. You can't get a good 6 volt battery below 6 volts (at rest) so eliminate the 4 lowest voltage batteries and EQ the other 3 strings individually (check voltage after to make sure that they did equalize) all batteries should now be equal voltage, if not, wait and EQ again.

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Kind regards

Tom Duffy
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From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Tump
Sent: Thursday, December 19, 2013 6:52 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Sick pack

What is the Spg (use a good refractometer)of each cell 1.11?1.15?  that temp is not to hi especially w/ the temp comp. Charging w/ the unit in bulk, the inverter will see voltage rise quickly and decide that they are charged. disconnect the batteries and check as individual units Eq at high voltage `32 v and a low charge rate 10 amps, watch the temp Spg .  I would suggest that if at all possible remove 2 sets and eq from the grid for ~week on /off.DO use a temp sensor and watch the spg. See Surrette's tech bulletin re/ highly sulfated batteries. www.surrette.com<http://www.surrette.com>.
Anything over 2 strings will cause a headache, BUT thats more the norm w/ the cheep off grid, I'm going to manage my gen run time kinda of folks!
On Dec 19, 2013, at 1:28 AM, frenergy wrote:

Gentlemen and women,

        I have been called in to deal with a pack of 16 (4 strings of 4 for 24V), L-16s, 6 years old.  She is having to run her generator 2 times a day.  Here in N.E. CA. its been cold, mostly clear, little wind.  Her inputs are about 1 KW of PV, and small wind machine and of course a serious generator.  Cables and terminals looked clean, were tight.  The bulk setting on the Trace 4024 was 28.0 V for 2 hrs with RTS, however, she would manually turn off the generator soon after it reached 28V.  Recipe for suphation.

        Rather than getting into too much detail, here's my quandary.  When I fired up the generator, the input amps in each of the 4 strings were.... string #1:29A, 2:34 A, 3:25 A, 4: 13 A.  A survey of IR temps throughout the pack gave temps ranging from 63 to 92 degrees.  The highest temps were in the string pulling highest amps.  In trying to find shorted/failed and/or sulphated cells which data are most relevant?  Temps, amp draw during charge, disconnect strings from each other and check volts of each 6 volt batt?, active bubbling? ...all the above?

        I'm thinking I should have (1) checked the amp draw with batts under load/genny off in each string AND (2) check amps between strings with the pack at rest, no input or output.  I would love to EQ the pack but with a temp already in the 90's and uneven currents in the strings I don't want to risk too high of temp or worse, a runaway situation and fire. I'm thinking I'd like to yank a few bad batts and run on 3 strings and then carefully EQ.

I appreciate any insights.

Thanks in advance,

Bill
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