T&T: 12 volt Charging options

[Gil Johnson]

Peter, right you are on RMS.  So, with the exception of an o'scope how would you read the actual p-p voltage?

Gil

----- Original Message ----
From: Peter Bennett <peterbb4@interchange.ubc.ca>
To: Gil Johnson <dogtrawler@yahoo.com>; trawlers-and-trawlering@lists.samurai.com
Sent: Tuesday, May 29, 2007 8:36:54 PM
Subject: Re: T&T: 12 volt Charging options


Tuesday, May 29, 2007, 3:52:28 PM, Gil wrote:

GJ> Jeff, I'm confused.  110VAC is 110-120VAC, meaning that it's
GJ> peak to peak voltage is 110.  Use any AC voltmeter and you'll
GJ> likely read something between 110 and 125 VAC.  If they are
GJ> suggesting a different method of measuring the voltage, it would
GJ> be helpful to understand.  Not having that point of reference
GJ> would make it impossible to troubleshoot a suspected voltage
GJ> problem.

No.  AC voltage is normally specified as the RMS (Root mean square)
value.  AC of a given RMS voltage will produce the same power as DC of
the same voltage.

The peak voltage of a sine wave is 1.4 times the RMS value - hence
120VAC RMS has a peak voltage of 168 volts.  Peak-to-peak voltage is
2.8 times the RMS value.

>From some previous comments (Arilds?), apparently some generators
produce a distorted waveform, with flattened (and therefore lower
voltage) peaks.

GJ> "In order to meet its ratings, 164 peak volts are required. A
GJ> battery charger uses only the top portion of the input sinewave.
GJ> Therefore, small variations in peak voltage results in large
GJ> variations in the amount of the waveform that the charger has to
GJ> work with. Standard public power of 117V has a peak voltage of
GJ> 164V."

GJ> Gil


-- 
Peter Bennett, VE7CEI    Vancouver, B.C., Canada
Lien Hwa 28 (AKA Polaris 30) "Sea Spray"
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