<div dir="ltr">I'm concerned about the battery you're planning to use. The small UPS batteries are usually 9AHr -- or said differently, can nominally store 108 watt hours. Each XO1 battery requires about 30 Watthrs.<div>
<br></div><div>And lead acid batteries should not be completely discharged, or they last a very short time -- maybe much less than a year.</div><div><br></div><div>So, say you had 5 hours of really good sun, and you got 80 watts from your panels. You'd need to store 400 watt hours of energy. The battery you're planning to use will not do what you need.</div>
<div><br></div><div>I am imagining that a "charger squid/bank" might include the MPPT controller, and the small battery to limit the voltage applied directly to the XO's (with the help of the MPPT controller, and it's DC-DC converter). The power from the solar panels will pass through the controller, go through a dc-dc down conversion, for the most part bypass the lead acid battery, and charge the XO's.</div>
<div><br></div><div>There is no low voltage cutoff, or even any voltage readout on the controller. I'm thinking that we nead a creative way to prevent excessive discharge of the battery. (I understand that UPS devices will quit when the voltage goes below 11.5. But the level of discharge is better indicated by a combination of voltage and current.</div>
<div><br></div><div>George</div><div><br></div><div><br></div><div>George</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Jul 23, 2013 at 7:27 PM, James Murdza <span dir="ltr"><<a href="mailto:james.murdza@dresden.us" target="_blank">james.murdza@dresden.us</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_extra">Thanks all for the outstanding amount of information. I think I will try a setup like so:</div>
<div class="gmail_extra"><br></div><div class="gmail_extra"><a href="http://www.ebay.com/itm/UNISOLAR-PVL-136-Watt-No-PeelNstick-SOLAR-PANEL-UNI-SOLAR-PVL136-PANELS-144-128/380679951769?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D62274773925413104%26pid%3D100011%26prg%3D1005%26rk%3D1%26rkt%3D5%26sd%3D231001584764%26" target="_blank">UNISOLAR PVL 136 Watt 24V Panel</a><br>
</div><div class="gmail_extra">-></div><div class="gmail_extra"><a href="http://www.amazon.com/Tracer1210RN-Solar-Charge-Controller-Regulator/dp/B008KWPGS6/ref=sr_1_5?ie=UTF8&qid=1374553109&sr=8-5&keywords=solar+controller+mppt" target="_blank">MPPT Tracer1210RN Solar Charge Controller Regulator 12/24V INPUT 10A</a><br>
</div><div class="gmail_extra">-></div><div class="gmail_extra">12V lead-acid battery. Originally a small UPS battery, but hopefully getting something more serious when everything else works and the funds are there.</div>
<div class="gmail_extra">
-></div><div class="gmail_extra">Directly to a bank of 5-10 XO 1s, using a charger squid/bank that I'm putting together myself.</div><div class="gmail_extra"><br></div><div class="gmail_extra">If I order the charge controller in the next 3 hours I can be sure that I will get it in time for my trip. Otherwise I'll have to fall back on my 12V controller. Please let me know—does this plan with the charge controller seem like a safe bet?</div>
<div class="gmail_extra"><br></div><div class="gmail_extra">Thanks!</div><span class="HOEnZb"><font color="#888888"><div class="gmail_extra">James</div></font></span><div class="im"><div class="gmail_extra"><br><div class="gmail_quote">
On Tue, Jul 23, 2013 at 1:38 PM, Richard A. Smith <span dir="ltr"><<a href="mailto:richard@laptop.org" target="_blank">richard@laptop.org</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><div style="overflow:hidden">So long story short is that if you want to use a PV panel with a voltage that is over about 2x your battery voltage you need a MPPT controller. While the Sunforce controller might work its going to be sub-optimal and I suspect will fail prematurely.<br>
</div></blockquote></div><br><br></div></div></div>
</blockquote></div><br></div>