<div>A little word of caution using "pop switch" tstats in a lead acid battery compartment, the gases produced during charging can be flammable, corrosive and explosive under the right conditions. Pop switches can produce sparks. </div>
<div>NEC Article 625 covers the external equipment to an electric vehicle that connect an electric vehicle for charging purposes. </div>
<div>A good rule of thumb is if you can smell the batteries charging you need to ventilate it.</div>
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<div>Steven Ray Webb </div>
<div>Texas Master Electrician 19870</div>
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<div class="gmail_quote">On Wed, Dec 17, 2008 at 8:01 AM, Ken Thomas <span dir="ltr"><<a href="mailto:kenscircus@aol.com">kenscircus@aol.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT: 1ex; MARGIN: 0px 0px 0px 0.8ex; BORDER-LEFT: #ccc 1px solid">I got some resistance wire, 25' of HWR-21168 from<br><a href="http://www.refrigeratorparts.com/" target="_blank">www.refrigeratorparts.com</a> and a couple pop-switch thermostats, stock<br>
number 802-STO-60, from <a href="http://www.mouser.com/" target="_blank">www.mouser.com</a>.<br><br>All 25' of the resistance wire was snaked around the batteries. The<br>batteries are split into two compartments so a thermostat is installed<br>
in series with each section of resistance wire. Each compartment gets<br>1/2 of the 25' but it is all wired in series. So, either thermostat<br>will turn the whole thing off.<br><br>The heater wire system draws 1.9 amps at 120 volts or 228 Watts. The<br>
wire is 2.5 Ohms per foot. The thermostats will keep the compartments<br>at about 50 degrees Fahrenheit. Still a bit cool but much better than<br>30 degrees. It will never turn on above 50 degrees.<br><br>The 1.9 Amps is low enough that it can be paralleled across the charger<br>
input without undue mains load while charging. I just leave it plugged<br>in all night (which I always do anyway) and it keeps the batteries from<br>getting lethargically cold.<br><br>Thanks,<br><font color="#888888"><br>
Ken<br></font>
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