Re: battery rating question
From: Glenn Ashmore (gashmore_at_cox.net)
Date: 03/16/05
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Date: Wed, 16 Mar 2005 07:34:34 -0500
The Amp Hour rating on wet and AGM batteries is the number of amps that can
be drawn over a 20 hour time period before the voltage drops to 10.5V. To
get the actual rate that can be constantly drawn divide by 20 so your 14 amp
hour battery can supply .7 amps. The total available amps drops a lot if
you increase the rate of draw. That 14 AH battery would last less than 30
minutes on a 15 amp load. The voltage would start out above 13V and drop.
It would be within 10% of 12 V (13.2V to 10.8V) for maybe 20 minutes.
Also to get the most use out of the battery it should not be discharged more
than 50-60%. AGMs can be drawn a little lower so the actuall usable amp
hours is about 7.
-- Glenn Ashmore I'm building a 45' cutter in strip/composite. Watch my progress (or lack there of) at: http://www.rutuonline.com Shameless Commercial Division: http://www.spade-anchor-us.com "tom" <cyberhun@shaw.ca> wrote in message news:UMUZd.693696$8l.239853@pd7tw1no... > If a 12 volt battery is rated at '14 amp hours', does that mean it is > capable of powering a load that draws 14 amps, at 12 volts, for one hour > before the voltage starts to sag below 12 volts? Or does it just mean that > if the battery was completely exhausted using a custom load that continued > to pull current out of it even as the voltage tapered off, and the total > power added up and restated in terms of 'amp-hours', it would be the > equivalent of 14, but the reality is that if you had a load that drew 14amps > at 12 volts, long before the hour was up, the voltage would drop below 12. > > How long would a typical 14 'amp hour' gel-cell run a 12volt, 15amp load > before the voltage dropped 10%? > > If you had a 12 volt gel-cell that was partially (say 1/3 )depleted, and you > simply hooked it straight up to a 12 volt ac/dc power supply, would it > recharge? What would happen when the battery was fully charged? > > > > >
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