For some reason, this was sent to me rather than mg-t@autox.team.net.
Reply to author, not me.
mjb.
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From: Roger Lewis <rlewis@tellumat.com>
Subject: TD Generator
Date: Wed, 29 Aug 2001 17:41:33 +0200
Andy, This mail is in response to the topic of fitting a TD with an
alternator in order to achieve the operation of halogen lamps.
In your case a number of modifications in the form of additional electronics
have been integrated with the electrical system based on the cars positive
earth arrangement, electronic ignition and the modified fuel pump to name a
few.
Depending on your priorities these items could be exchanged for those
appropriate to a negative earth system, and then you could continue with
your desire to fit an alternator. In fact the need for an alternator cannot
be substantiated, the real problem with the TD is not the generator but in
fact relates to the regulator. TC's,TD's and early MGA's where fitted with
the two pole regulator which if in good condition and set correctly just
does the job based on the original design criteria and setup of the system,
including the type of battery available at that time. As a point of interest
those running with the more modern non ventilated batteries could be looking
for trouble as these batteries are not ideal for applications which expose
them to consistent overcharging. That is with the regulator set as
originally specified.
is done in order to compensate for the voltage drops that occur in the
regulator under load operation, under light load conditions the battery
becomes overcharged, this as reported by others responding to your interest.
Under full load the voltage drops because the load current flowing through
the regulator is influencing the operation of the voltage coil. Simple put
lower the voltage to prevent the current exceeding the safe limits of the
generator. So if you drive a lot with head light on, you need the regulator
set high in an effort to restore any lost charge from the battery. A lot day
driving and the battery get overcharged.
The solution is in fact to either fit a more modern three pole regulator as
fitted, for example to the MGB. This type of regulator manages the voltage
and current control requirements separately and would be a simpler
modification than fitting an alternator.
I assume you are not an originality boffin. This type of modification has
been done with the newer type of regular being wired to the old regulator
terminals and then hidden inside the tool box, those responsible for such a
devious changes remaining anonymous, however the modification is a very
practical one.
What has also been achieved is the professionally design of an electronic
regulator which overcomes the limitation in place back in the 40's and 50's.
Such devises are currently undergoing trails in a number of T Types here in
South Africa. The unit is designed to fit inside the original regulator
casing. The stability of output from the generator is within 0,5 volt of
14,4 volts from no to full load which is controlled to 20 amps. It also
manages the correct operation of cutting in and out the generator without
the need of using large heat dissipating diodes, for those of you that
understand these things you will hopefully appreciate what I am talking
about.
In short the T type generator will supply a stable 14.4 volts at up to
20amps, more than enough to run the system.
Good luck with your chosen solution.
Roger Lewis
------- End of forwarded message -------
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