Lead acid batteries won't freeze unless discharged more than 50%.

for winter, just insulate them well to shield them from severe temperature 
spikes and make sure you have more charging power than you need, and you're 
good to go.




++++++++++++++++++++++++++++++++
<insert witty tagline here>

----- Original Message ----- 
From: "Chuck McCown - 3" <[EMAIL PROTECTED]>
To: "WISPA General List" <wireless@wispa.org>
Sent: Wednesday, November 19, 2008 6:48 PM
Subject: Re: [WISPA] Remote Powered Access Pont


> We buy batts that are rated to give you the energy down to -20F.
> Survive being at-20F while discharged to a stone cold state.
> And recover when the next available bit of sunlight hits the panel 
> (perhaps days later).
> And last 2000 cycles.
> For that you pay 30 cents per watt hour.  And can sleep at night.
> (we used to get these for 20 cents, I don't know why they are so much more 
> now)
>
> I just found a website selling a T-105 for $160\each
> 6 volts, 225 aH  That comes to 11.8 cents per watt hour.
>
> The Trojan website says "avoid locations where freezing temperatures are 
> expected".
> It also says the must be kept fully charged when freezing.  Hard to do 
> with solar on a mountain top.
>
> http://www.trojan-battery.com/Tech-Support/documents/UsersGuide_0708_English_003.pdf
>
> So, if you have a nice warm place to keep the trojans then they are a very 
> good value.
> (assuming they are in an air conditioned place in the summer too, else 
> they won't last too many summers)
>
> But most solar powered sites don't have a heater to keep them from 
> freezing and splitting.
>
>
>  ----- Original Message ----- 
>  From: Blair Davis
>  To: WISPA General List
>  Sent: Wednesday, November 19, 2008 7:25 PM
>  Subject: Re: [WISPA] Remote Powered Access Pont
>
>
>  What type of battery's are you using?  That price sounds very high.
>
>  4x T-105 will provide 225Ah at 24V for a cost of about $500
>
>  Chuck McCoy's - 3 wrote:
> I would use a 100 watt panel minimum.
> And a one month battery.  5watts * 24hours * 30 days = 3600 watt hour
> battery
> If you are running a 24 volt system then you need 3600/24=150 aH battery.
> If you are running a 12 volt system, you need a 300 aH battery.
>
> You will pay about 30 cents per watt hour for a battery.  So $1080 for the
> battery.
> You will pay about $5/watt for the panel, so $500 for the panel.
> Charge controllers are about $100 or less.
>
> If you build it this way it will always work.  You can put in half the
> battery for half the price.  But then you have only two weeks of insurance
> against bad weather.
>
> Never ever go below 10X the load for the panel, that will just barely cut 
> it
> in the sunniest of climates.
> Even then you will probably have to put in a back up generator and you 
> will
> be cycling the crap out of your batts causing them to only last a couple 
> of
> years.
>
> If you want 99.999% reliability you have to use a panel 24X the size of 
> the
> load (unless you have a tracking mount, then you can reduce that).
> I try to always use 20X panels and no less than a 2 week battery.  But 
> even
> then, a week or two of snow on the panels and gray skies every day can 
> cause
> an outage.
>
>
> ----- Original Message ----- 
> From: "Scott Parsons" <[EMAIL PROTECTED]>
> To: "'WISPA General List'" <wireless@wispa.org>
> Sent: Wednesday, November 19, 2008 5:33 PM
> Subject: [WISPA] Remote Powered Access Pont
>
>
>  I'm looking into setting up a remote access point/repeater.
> Power requirements are 5W. No access to grid power.
>
> I was curious what you guys use for this type of thing?
> I figure I need a 30W solar panel, controller, battery and enclosure.
> How much should I expect to pay for a setup?
> Is there anything available off the shelf?
>
> Thanks for your help.
> Scott
>
>
>
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