Testing the charging system is pretty easy in this case to determine if the
problems you are experiencing are generator/alternator or battery related.
You'll need a volt meter to do the testing- not a test light.
With everything off, the voltage at the battery will be ideally around 13
volts. It can vary a bit though. Write that voltage with everything off
down. Now start the car. The volt meber should jump up to 14 volts or so
when you rev the engine up. At idle it may actually be below 12 volts due
to the design of the Lucas units- they just don't put out at low RPM's like
the more popular aftermarket AC-Delco units. That's still fine since you
don't sit idling forever. The
The battery needs at least 12.6 volts in order to charge. That half a volt
is the key. If you are finding the electrical system is at a lower voltage
with the car running versus when the car isn't, then you are actively power
discharging the battery! A coil needs at least 8 volts to run. 10 volts
at the battery will keep the coil alive.
Okay, so the electrical system keeps the voltage up at 12.6 volts or above.
Great! Now turn on the headlights. The voltage at the battery drops
again. It should not drop below that 12.6 volts though. If it does, rev
up the engine and make sure that it does increase above that threshold. If
it does not get above that, then you've got two possibilities:
1) The generator/alternator is no longer capable of supplying enough
current to keep the system up with the demand put on it (headlights, heater
motor, radio, etc).
2) The presence of a heavy short/sneak path to ground on the headlight
circuit that is putting a heavy load on the system and bringing it overall
down too low to keep up with the generator/alternator.
The fact that you have seen surges in current with the lights getting
brighter than even normal from time to time indicates a problem not with a
short circuit, but instead an electrical failure internally with the
alternator or the voltage regulator if it is a generator. I suspect you
have a generator from your email message. The voltage regulator would have
failed for the voltage cutoff to prevent overcharging. I have written up
an article on testing voltage regulators and Spitfire charging systems in
general if you wish to peruse it, though realistically it's easier to just
replace the unit. It has a lot of diagrams and test values to compare with
as well as adjustment information for the three coils found inside a
voltage regulator. I also have step by step instructions (with photos!) on
doing an alternator conversion there as well.
Voltage Regulator Testing / Adjustment:
http://www.ponypics.com/spitfire/regulator.html
GM Alternator Conversion:
http://www.ponypics.com/spitfire/alternator.html
-Vegaman Dan
-68 Mk III (Giles)
________________________________________________________________________
| | 1968 Triumph Spitfire Mk III * Furry Artist |
| Flinthoof |--------------------------------------------------------|
| | MINTMINTMINTMINTMINTMINTMINTMINTMINTMINTMINTMINT!! |
| Dan |--------------------------------------------------------|
| Canaan | ConiFur NorthWest 2001 - Furries in Seattle! |
| |--------------------------------------------------------|
| CONIFUR NW | Flinters@picarefy.com * http://jarmac.picarefy.com |
|_____________|________________________________________________________|
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