[RE-wrenches] FLA battery setpoints with larger arrays
boB at midnitesolar.com
boB at midnitesolar.com
Fri May 22 11:47:20 PDT 2015
In addition, when someone leaves the system for long periods of time,
the ending amps can help BUT that is
not the same as giving them a good de-sulfating Absorb cycle once in a
while.
This is where it is nice to give them a good Absorb for some hours
without the ending amps but only
every so often. Maybe once per week or two ? Jay and I talked about a
"Vacation Mode" a while back..
The Classic can be set to skip a number of days of Bulk/Absorb cycles.
This works well.
You can also set a high battery temperature to stop charging at. It's in
one of the CHARGE menus.
There are all sorts of neat things you could do to keep FLA batteries
alive longer I think.
Like what Kent Osterberg in Oregon mentioned... Every so many days,
start a timed Absorb
after the current has fallen below ending amps.
So many good ideas, so little time !
boB
On 5/22/2015 10:17 AM, Dan Fink wrote:
> Bill; The Whizbang can mount on the main shunt, and has an included
> mounting option that lets you piggyback the wires from another
> amp-hourt meter on it. I have mine with a magnum ME-BMK piggybacked on it.
>
> Dan Fink
> Buckville Energy
> IREC Certified Instructor™ for:
> ~ PV Installation Professional
> ~ Small Wind Installer
> NABCEP / IREC / ISPQ Accredited Continuing Education Providers™
> 970.672.4342
>
>
> On Fri, May 22, 2015 at 8:28 AM, frenergy <frenergy at psln.com
> <mailto:frenergy at psln.com>> wrote:
>
> Hey Jay,
> From what I've heard form battery manus, the C rates
> likely even in a well PV-ed system still will not produce C-rates
> high enough to approach a high or "longevity reducing" internal
> battery temp, assuming a typical bulk, absorb, float cycle. Of
> course, battery environmental location (typical temps) would set a
> baseline from which batt temp would rise from. Here in the
> Sierra, ambients are not very high 95% of the time.
> Just curious, how does the wiz bang account for all
> loads...2 shunts?
> Thanks,
> Bill
> Feather River Solar Electric
>
> ----- Original Message -----
> *From:* jay peltz <mailto:jay.peltz at gmail.com>
> *To:* RE-wrenches <mailto:re-wrenches at lists.re-wrenches.org>
> *Sent:* Thursday, May 21, 2015 8:07 PM
> *Subject:* Re: [RE-wrenches] FLA battery setpoints with larger
> arrays
>
> Hi Allan,
>
> I like the classic/wiz bang jr. This allows really good end
> amp control as all loads are accounted for.
>
> Higher C rates equal higher internal temps which definitely
> will shorten the life.
>
> On Thu, May 21, 2015 at 10:56 AM, Allan Sindelar
> <allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>> wrote:
>
> Wrenches,
> In the last few years I have changed my approach to off
> grid system sizing, primarily due to higher battery costs
> and lower module costs. Rather than shooting for a
> traditional 80-90% of winter load profile target, I will
> size a larger array and smaller battery bank, figuring
> (especially here in the sunny Southwest) that batteries
> will recharge more quickly, will spend more of their time
> full (and thus last longer), and will be at least
> partially charged during cloudy weather. This even allows
> for smaller battery banks that are cycled more deeply (as
> long as there's a backup gennie in the mix); the lower
> cost of a smaller size may allow for a set of
> higher-quality industrial cells.
>
> I first began to rethink my design approach after reading
> Christopher Freitas' Solar Pro article on large battery
> banks a few years ago. Being able to refill in a day was
> part of his strategic approach to battery bank design. I
> used and wrote about this approach in my tiny house
> article in the current Home Power. However, I'm just
> beginning to get owner feedback about greater water
> consumption and the need for more frequent watering. This
> is especially the case when I add array to an existing
> system, and the old watering schedule is suddenly not enough.
>
> When I design new systems I now encourage larger arrays
> and smaller battery banks, as the batteries spend more of
> their time happily full and recover more quickly after a
> discharge period. But I am thinking that I will have to
> begin changing charging setpoints in response. Flooded
> batteries have a range of recommended bulk setpoints, from
> 28.8 to 29.6 volts on a 24V system. When arrays were
> smaller we set to the higher end of the range to take
> advantage of topping off when available, and a two hour or
> longer absorption was considered beneficial, as long as
> the CC could transition to float at 2% of capacity or so.
> With a larger array a better approach may be to lower the
> bulk/absorption setting, as well as reduce absorption time
> and raise the float transition current ("done amps").
>
> I'm writing to encourage a discussion among off grid
> Wrenches. Are you changing the relative relationship
> between array and battery capacities? If so, how are you
> adjusting charge controller setpoint programming? For
> example, how would you program a Midnite Classic, Outback
> FM or Schneider XW if you could achieve a C/10 or C/15
> charge rate?
>
> Thanks, Allan
>
> *Allan Sindelar*
> allan at sindelarsolar.com <mailto:allan at sindelarsolar.com>
> NABCEP Certified PV Installation Professional
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Founder (Retired), Positive Energy, Inc.
> *505 780-2738 <tel:505%20780-2738> cell*--
>
> Jay Peltz
> Peltz Power
> jay.peltz at gmail.com <mailto:jay.peltz at gmail.com>
>
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