Mailing List lml@lancaironline.net Message #6189
From: <RWolf99@aol.com>
Subject: Battery Capacity
Date: Wed, 2 Aug 2000 17:24:30 EDT
To: <lancair.list@olsusa.com>
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In a message dated 8/1/0 9:59:37 PM, you wrote:

<<Manufacturer's most commonly design their lead-acid batteries for a
ten hour discharge, but some are designed for shorter or longer discharge
times. I again spoke with Concorde and was surprised to learn that their
aircraft batteries are optimized (and rated) for one hour discharge>>

You need to look at the fine print on battery capacity.  The "rated capacity" is a function of discharge rate, although that rate is not always mentioned in the advertisement.  Here's how the secret code works:

A C/5 rate ("C over 5") is when the battery is fully discharged over a five hour period.  A C/10 rate ("C over 10") is when you suck out the power over a ten hour period.  We'd be interested in a C rate (one hour discharge).  The fine print may say C/2 or C/5 or something similar.  As Dan says, you get less if you suck it out faster.  I suppose there's a rule of thumb for how much less you get when you draw it out faster, but I don't have that info available to me.

- Rob Wolf

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