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RE: trickle charge optima battery

To: "Triumphs List" <triumphs@autox.team.net>
Subject: RE: trickle charge optima battery
From: "Randall" <tr3driver@comcast.net>
Date: Fri, 23 Sep 2005 07:12:51 -0700
> AHA!  This makes much more sense to me.  I suppose the high rate
> chargers (i.e. not alternators) may run at a higher voltage then the
> automobile alternator.

Yes, definitely.  The peak voltage of even low rate chargers is higher than the
alternator.

> What is the nominal output voltage of a modern alternator ?

It's a curve, varies quite a bit with temperature.  ISTR 14.6 @ 70F is about
right, but I won't swear to that (and I'm too rushed to look it up at the
moment).

> I 'd have to check, but I seem to recall that when I set my voltage
> regulator for my generator on my 4A,

The regulator used on TR2-4A is a special case, because it uses a single relay
to regulate both current and voltage.

>  I would strongly
> suspct that the voltage at the battery terminal will NEVER reach the
> voltage to which the regulator was adjusted....  Do you agree?

Yes I do.  However, it's also true that the TR2-4A control box allows the
battery to be overcharged slightly under light load (and undercharged at heavy
load).  This is the compromise of the two-bobbin regulator that Triumph chose to
use on the TRs, likely to reduce costs.  Lucas did make a three-bobbin
regulator, which was used on some Triumphs (like Spitfires and my Sports 6), so
cost is the only reason I can think of for using the 2-bobbin.  Or possibly
Lucas hadn't offered the 3-bobbin yet when the TR2 was designed, and no one
thought it was worth switching for the later TRs.

How much the overcharge shortens battery life, I can't say.  But I do believe it
causes outgassing on long trips, which can lead to fine droplets of sulfuric
acid being spread around the battery and causing corrosion.

Randall




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