[RE-wrenches] Electrolyte Dilution vs Voltage

[Dave Angelini Offgrid Solar]

Definitely agree and can't believe people still do multiple strings with
so much choice out there.
>From Red October, "one ping Vasili, one ping only"  --Dave

> One of the biggest issues I find w/ battery installations is  instead of
> using larger capacity 2 volt cell batteries, there are “installers”
> that install string after string of 6VDC batteries and wire them without
> buss bars, so the last string contributes very little during discharge &
> gets very little charging. Who really wants to take service 144 battery
> filler wells? (2100 Ahr when using L16s@ 350Ahr for 48 vdc.) Its no wonder
> why battery banks suffer from neglect. According to  Surrette's battery
> installation and warrantee guide for # of maximum strings per battery
> bank; Preferably 2 no more then 3 strings. ( Steve please correct me
> here). Buss bars  are cheap, when amortized over the life cycle of an
> installation and are easily configured W/ shunts if one choses to install
> multiple strings. Buss bars also improve battery performance both during
> discharging & charging, & they also facility the installation of an inline
> class “T” fuse
>> On Jul 18, 2018, at 9:33 PM, William Miller <william at millersolar.com>
>> wrote:
>>
>> Colleagues:
>>
>> I believe that circulating currents in multi-string battery
>> installations are a major cause of premature failure of such a system.
>> I think it is important to monitor these currents.  Most telling would
>> be checking these currents in an at-rest scenario.  It would be helpful
>> to have a baseline at install and then check periodically.
>>
>> Measuring these currents with any type of DC clamp-on meter can be
>> inaccurate at best.  In a conversation with Steve Higgins at a recent
>> trade show I came up with this idea that may have some merit:  If an
>> install has more than one string of batteries, install an appropriately
>> sized shunt in the negative lead of each string.  At any later date you
>> can apply any decent voltmeter with a millivolt scale and check for
>> battery string imbalance with some degree of accuracy.  Shunts are cheap
>> and readily available and if you avoid the brand that Outback uses in
>> the Radian GSLC cabinets, they are relatively rugged.
>>
>> We will be trying this in any future install with multiple strings,
>> although we avoid this if at all possible.
>>
>> William Miller
>>
>> <image002.jpg>
>> Lic 773985
>> millersolar.com <http://www.millersolar.com/>
>> 805-438-5600
>>
>> From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org
>> <mailto:re-wrenches-bounces at lists.re-wrenches.org>] On Behalf Of John
>> Blittersdorf
>> Sent: Wednesday, July 18, 2018 6:24 PM
>> To: RE-wrenches
>> Subject: Re: [RE-wrenches] Electrolyte Dilution vs Voltage
>>
>> Mac,
>>   I was about to ditto Ray with his more common than I would like
>> scenario of battery death when I saw your mention of the 2nd string
>> not connected.  It is always nice to see
>> a solution that is simple and should have been considered, but wasn't.
>> The assumption with battery issues usually is that they are actually
>> hooked up!  I often thought that it would be worth the money to supply a
>> cheap AC/DC clamp meter with every installation so that a phone
>> consultation could quickly determine if the strings were unbalanced and
>> what might be the reason.  Bad cells and bad connection  will usually
>> show up in a current check and then a quick voltage check of each
>> battery with a load on the system will show the culprit if a bad cell
>> and corrosion present might find the bad connection.  I use Interstate
>> L16's most of the time and find that the life is typically 6 years.  I
>> used to call them a 7 to 10 year battery but kept racheting back the
>> claim until I now call them a 5 to 7 year battery with more if properly
>> maintained.  I have seen 10 years but it is rare.
>>
>> John Blittersdorf
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Dave Angelini Offgrid Solar
"we go where powerlines don't"
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