[RE-wrenches] FLA battery setpoints with larger arrays

[boB at midnitesolar.com]

On 5/23/2015 11:37 AM, Luke Christy wrote:
> 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?


As long as some FLA battery systems use "vent fans", just arrange them so
that they move air past the batteries to cool them at the same time ?
That's when they're going to get hottest anyway.

FLA batteries will freeze easier if they are discharged.  I suppose that 
you could
use the battery temp sensor to make sure you charge them up good when
the temp gets cold enough.

boB



>
> 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
> Message-ID:
> 	<CAGr8+7chy-FBp8yzQbNp4T7+wKLyE2LjJ6zy97w=6dqJhKTLQA at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> 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
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>
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>