[Mg-t] Battery issue

[Bob Donahue]

MG originally set the charging voltage to 16 volts on the T cars. (Correct
me if I'm wrong. I base this statement on the operation of my original
voltage regulator, and the alignment procedure in the shop manual.) This is
too high, 16 volts will boil out the electrolyte. For the life of me, I
don't know why MG set it so high. I set my regulator to 14 volts at running
speed. (Apparently there are several different battery types now that
require slightly different charging voltages.14 volts is supposed to be good
for the AGM/Optima battery.)

Before I re-adjusted my regulator, and when I had a conventional non-sealed
battery, the battery consistently barfed up acid.

As for the Optima Red Top, I've had one for ten years now. I have no
accessories to drain the battery during storage (the original clock is
missing). I store the car during over the winter from October to April. The
battery maintains a full charge (12.6 volts) with out any charging at all
over that period.

BTW: Generators, like in our T cars, do not charge at idle speed. Our
batteries actually discharge waiting on the traffic light. Alternators do
charge at idle. I remember the old days when everyone had a generator, it
was possible to run down the battery in a traffic jam especially at night
with the headlights on.

Bob Donahue (Still Stuck in the '50s)
Email - bobmgtd at comcast.net
Cars:       52 MGTD - #17639
               71 MGB - #GHN5UB254361
Member:  NEMGTR #11470
               NAMGBR # 7-3336
               Hoosier MGB Club
               Olde Octagons of Indiana

----- Original Message ----- 
From: "Stuart C. Keen, Jr." <simbafish at comcast.net>
To: "MG" <mg-t at autox.team.net>
Sent: Thursday, January 15, 2009 10:12 AM
Subject: [Mg-t] Battery issue


> I9m having an issue with batteries in my TD. Hopefully someone has an
> answer. I am going though Optima batteries like they were the greatest
> thing
> since sliced bread. Why are Optima batteries failing so frequently (every
> 2.5 years or less) when placed in my TD?  Perhaps the below facts and data
> will reveal cause of problem. Please let me know of any other tests I
> should
> be making.
> MG @ 2000 - 3000 rpm    charging voltage 14.00 to 15.00  vdc  (seems to
> depend on how close the battery is to being fully charged)
>
>
> The Optima web site states the battery should maintain a voltage of 12.6
> to
> 12.8. It should NEVER be allowed to fall below 12.6 volts, otherwise it
> will
> start to sulfate. If I don9t drive for a couple of days, the battery will
> drop to 12.00 or lower! Is this normal?
>
> With ignition OFF, drain on battery in the MG is 16 MA (0.016 Amps). This
> is from a car alarm and standby voltage  for Radio and CD Player.  When
> driving (without lights) the dash ammeter charging amperage looks approx
> Plus 3 amps. With lights on, the dash ammeter reads basically ZERO.
>
> I checked this morning  the status of the battery in my General Motor9s
> CTS
> after non-use for 2.5 days. It reads 12.01 vdc. However, when I start the
> CTS, the charging voltage jumps to 14.5 vdc @750 rpm. The MG only shows a
> charging voltage of 11.9  at start up (idle) unless revved to 2000 rpm. Is
> the MG suppose to show full charging voltage (14 - 15 vdc) when starting
> and
> idling or is this normal for 3unsophisticated2 classic cars?