I would agree with Richard that the off-grid people I work with are still using the lead-acid flooded batteries because they provide the most number of cycles for true deep discharging (50% -- we do all our calculations assuming only 50% discharge and about .88 system efficiency; with an inverter, the efficiency is more like .77). <br>
<br>I've heard that some of the VLRA batteries have seriously shortened life expectancy with temperatures other than 70F.<br><br>As for smaller charge controllers, I like the Morningstar line of controllers (<a href="http://www.morningstarcorp.com/en/products">http://www.morningstarcorp.com/en/products</a>). The little 4.5A one, the Sunguard, is in the $30 range. I recommend it to anyone buying 20-50W solar panels to charge a 12V battery (for instance). The Sunkeeper and SunSaver are the next size up (6-25A), $50-90.<br>
<br>Kim<br><br><br><div class="gmail_quote">On Sat, Mar 6, 2010 at 7:01 PM, Richard A. Smith <span dir="ltr"><<a href="mailto:richard@laptop.org">richard@laptop.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
On 03/06/2010 06:26 PM, Paul Fox wrote:<br>
<div class="im"><br>
> smith wrote:<br>
> > when you go into a large %DoD. If you take a LA battery below 50% DoD<br>
> > on a regular basis you will destroy it. So for 8Ah of juice you need a<br>
><br>
> is it this effect that so-called "deep discharge" batteries are<br>
> better at?<br>
<br>
</div>Consumer deep cycle LA batteries aka "Marine" batteries mean that you<br>
can pull them down on a semi-occasional basis and they won't die<br>
Opposed to say a car battery where 5 deep cycles and its toast.<br>
<br>
A consumer grade deep cycle battery is fine for running your trolling<br>
motor or your UPS but not in the same league as a LA battery designed<br>
for alternative power use. They are designed for discharge use on a<br>
daily basis.<br>
<br>
They are doing pretty fancy things these days with LA. I see a lot of<br>
VLRA [1] types when I've been doing searches for capacity pricing. The<br>
big big boys however are still flooded cell.<br>
<br>
Once LiFePO4 (LFP) batteries come down a bit more in price LA will be a<br>
thing of the past. LFP is superior in every category except price.<br>
Even now if you look at long term life and TCO LFP wins but its still a<br>
good bit more expensive on the front end.<br>
<br>
[1] <a href="http://en.wikipedia.org/wiki/VRLA_battery" target="_blank">http://en.wikipedia.org/wiki/VRLA_battery</a><br>
<br>
Funny the wikipedia article doesn't list alternative power under<br>
applications.<br>
<div class="im"><br>
--<br>
Richard A. Smith <<a href="mailto:richard@laptop.org">richard@laptop.org</a>><br>
One Laptop per Child<br>
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