[TR] alternator conversion in a tr3

Randall TR3driver at ca.rr.com
Tue Jun 2 23:49:02 MDT 2015


> It is a long story, (don't ask it hurts,) but in reality a 
> LED bulb will not 
> complete the charging circuit at low engine revs under 2000- 
> 2500rpm. Fact.

An easy solution for that problem (sorry, Dixie) is to add a resistor in parallel with the lamp.  The resistor is a good idea anyway
(IMO) in case the bulb ever burns out (or fails to make contact).  I had one on my TR3A with alternator conversion, simply soldered
to the back of the bulb holder but sticking out a bit to keep the heat away from the plastic.

Also, some alternators (the ones that can be used in a "one wire" configuration) will not exhibit the above problem.

However, there is another potential problem with the ignition warning lamp; which is that it can see substantial reverse voltage.
Not all LEDs can withstand that much reverse voltage without damage.  So a series diode may also be required.  The diode may also be
needed if you have an electronic ignition that has it's own power feed, like an MSD 6A.

There are also some TRs where the turn indicator lamp operates with both polarities (eg 69 TR6).  They will also need some
modification to use an LED for the indicator (in addition to the mods to use LEDs as turn signals).

-- Randall  



More information about the Triumphs mailing list