On 5/22/2015 12:56 PM, Ray Walters wrote:
Hi Bill;
If the battery is in an insulated box indoors, it definitely can over
heat. Also if ambient temps get into the 90s, the additional heat
from charging can push the battery into the danger zone. In hot
desert or tropical climates, it may actually be difficult to keep the
battery below 105F.
I'm very glad to hear Midnite added the high temp disconnect to their
system. They may have saved a life.
Bob, is battery temp logged, so we could see how often a system quits
charging for high temp, and just what the battery temps are running?
No, but that is on the list as are other things to data log.
Hopefully the temperature is adjusted higher than it would ever get to
under normal circumstances.
I could see some future systems wanting to be able to regulate Absorb on
battery temperature mixed with other
parameters some day. Could get REALLY complicated if you wanted to.
We're learning more and more
about what is good for batteries.
boB
Many of our systems may need additional cooling. A recent HUP install
in Haiti comes to mind.....
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 5/22/2015 8:28 AM, frenergy 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.pe...@gmail.com>
*To:* RE-wrenches <mailto:re-wrenches@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
<al...@sindelarsolar.com <mailto:al...@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*
al...@sindelarsolar.com <mailto:al...@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.pe...@gmail.com <mailto:jay.pe...@gmail.com>
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