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	<title>Ham Radio Help Desk &#187; gel cell</title>
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	<description>Hams helping hams make the most of the hobby of amateur radio.  (This site is moving from www.hamhelpdesk.com to www.hamradio.me)</description>
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		<title>Battery Energy Density: Gel Cell</title>
		<link>http://www.hamradio.me/power-supply/battery-energy-density-gel-cell.html</link>
		<comments>http://www.hamradio.me/power-supply/battery-energy-density-gel-cell.html#comments</comments>
		<pubDate>Tue, 16 Jun 2009 22:07:14 +0000</pubDate>
		<dc:creator>kx4o</dc:creator>
				<category><![CDATA[Power Supply]]></category>
		<category><![CDATA[battery]]></category>
		<category><![CDATA[gel cell]]></category>

		<guid isPermaLink="false">http://www.hamhelpdesk.com/?p=814</guid>
		<description><![CDATA[For backpacking is a Gel Cell battery the logical choice?]]></description>
			<content:encoded><![CDATA[<p>Working at an airplane company as an EE certainly puts energy density of electrical storage components at the top of the list of important things.</p>
<p>Of course the buzz word of the decade when talking about batteries is Lithium, Lithium, Lithium.<br />
<span id="more-814"></span><br />
Sure enough batteries based on Lithium chemistry yield energy densities exceeding 100 Wh/kg and quite often much higher.  That&#8217;s great.  However, let&#8217;s compare it with a typical gel cell type lead acid battery.</p>
<p>My example battery is a Yuasa NP7-12.  Complete specs include:</p>
<ul>
<li>Make: Yuasa</li>
<li>Model: NP7-12</li>
<li>Voltage: 12V</li>
<li>Amp-Hours: 7 AH</li>
<li>Calculated Watt Hours: 84 Whrs</li>
</ul>
<p>I weighed the battery and it came to about 6 pounds or 2.7 kilo-grams.</p>
<p>Thus, the energy density is about&#8230;</p>
<div align="center">
84 Whrs / 2.7kg = 31 Whrs per kg.
</div>
<p>This is less than one third the capacity of most Lithium battery types.</p>
<p>On the other hand, it is not that radiacally different and the good old Gel Cell is a battery type very well understood by a great many folks.</p>
<p>Weight matters in my application because I have to carry this power source up a few thousand feet of steep trails to reach the White Rock Cliff Station 6 of the Appalachian Trail Golden Packet (ATGP) attempt.</p>
<p>A 7 AH battery is probably good enough for the Kenwood D710 in this particular project, but I am not yet convinced this is true.  Calculations for the energy needed for the ATGP is for a future post.  Stay tuned.</p>
<p>If I can trade battery weight for water supply I think I will be much happier.</p>
<p>John</p>
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