[RE-wrenches] FLA battery setpoints with larger arrays

[Luke Christy]

Jay's point about adding PV to offset daytime AC for the battery bank brings up the issue of active cooling. 

How many folks out there are installing some form of cooling for LA battery banks, and how are you implementing it? 

The issue of excess heat being an enemy of battery life has had me concerned for several years now, and I have started installing multiple fans in battery boxes to increase the cooling from air circulation, but I'm not sure I have the effectiveness dialed yet. 

Interested to hear what others are doing here.

As always, I appreciate the great resource that is this list. 

-Luke



Message: 2
Date: Fri, 22 May 2015 17:07:05 -0700
From: jay peltz <jay.peltz at gmail.com>
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: Re: [RE-wrenches] FLA battery setpoints with larger arrays
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	<CAGr8+7chy-FBp8yzQbNp4T7+wKLyE2LjJ6zy97w=6dqJhKTLQA at mail.gmail.com>
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Hi Ray,

Cold isn't a problem.  It reduces capacity and yes they could freeze, but
it doesn't shorten life ( I mean besides the freezing part) in fact cooler
batteries last longer.
But hot is a problem. Those max temps are not the same thing as reduced
life from running at a hotter temperature.


As to internal temps, its really hard to do this.  IR cameras are pretty
good.  Temp sensors which stick to the outside of the case's are not as
good as ones that bolt to the post.  The post is a good thermal conductor
vs the plastic case.  The glue/stick on ones come loose as we all know and
that means less accurate metering.

My premise for bring up the temp concern is that with a larger array and
smaller battery which equals higher C rates you will have higher internal
temps, no way around it.  How high, how much/will it shorten the life
unclear but probably, how much, ?

Let me rephrase it, do you think hotter temperatures are increasing the
lifespan of the battery?

While on this subject, I've done some quick calcs and with hot areas, its
cheaper to add PV for installing daytime AC vs battery life lost due to the
heat.  We can thank the cheap world of PV for that.

And while I've thought about what Allan started this conversion with in
regards to sizing batteries.
I continue to size my batteries around best life for the battery  ( best
daily average % DOD).
There are many ways to consider the size/cost etc of batteries:  For a
larger battery (less DOD)  you could view it as buying lead futures, longer
time between problems, etc.  For smaller bank ( higher DOD)  my only reason
for doing it at this point is a bridge battery to when Li-Ion/other
technologies will overtake LA for cost/ease/MX/capabilities.

I'd be curious to hear what others think about that last part,

jay




Luke Christy

NABCEP Certified PV Installation Professional™: Certification #031409-25 
NABCEP Certified Solar Heating Installer™: Certification #ST032611-03       
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