I had an alternator conversion last summer, and the ammeter reading has been very stable at the middle position ever since. I de-hibernated my Mk2(1964 3.4 man/od) 2 weeks ago and drove it home; everything normal. 3 days later driving to the workshop; everything normal.
I collected it today, noticing the panel light switch was put in the UP/Bright position. The workshop boss has test-driven the car after a differential repair, and the panel lights has been left switched ON for 2 or 3 days while the battery cut-off switch NOT activated. I turned the panel light off and started just fine. So the battery has not been drained, but the ammeter is now acting very strange. It wobbles and sits halfway to right/Discharge when driving/revving, and reverts to middle when idling. The meter also react markedly when activating turn signals and headlights etc. Getting home I noticed the panel lights is not working at all any more.. Is it possible that leaving the light ON for several days has caused a short circuit/overload in a voltage regulator/stabilizer which is now further interfering with the entire electrical system?

 

I don't think so?

maybe if you look for any signs that the gauge itself was messed with while at the shop?

 

Thanks Jose, you are absolutely right. The manual states that the panel light can only be activated with the main lights switch is ON. good thing i didn`t make a fool of myself asking the workshop :-)
The panel light is still broken, though. Maybe the bulb just died?
Have to figure out why the ammeter is dancing, will check for stable charging voltage during the weekend.

 

try exercising the switch between the on and off positions, with the engine running, to see if the light comes on.

Lack of use causes these Lucas toggle switches to become erratic.

as a last resort, replace the bulb.

 

Are you using an ammeter or a voltmeter with your new alternator?
JP

 

My Mk2 has the original Lucas "AMPS" ammeter. I hace installed the SNG Barratt alternator conversion kit including the Lucas LRA300 [12Volts, 55Ampere]. The meter should not move to "discharge" while driving, nor move in time with the turn signal/lights?

 

Maybe this article will shed some light :-) on the problem:
In-car Amp meter with Alternator
My Mk2 has an alternator, but I replaced the original ammeter with a voltmeter to measure output voltage rather than current flow.
JP

 

Jose, working the toggle switch made the trick, the panel light is back;
FIAT LUX :-)
I drove ca. 50 km tonight, and the ammeter needle stays just above the middle position towards "Discharge" at 80 km/h cruising, but not that far above as a few days ago. I measured the charging voltage across the battery terminals at 800-2000 rpm. idling with different loads in 200 intervals. Compared to last year it has decreased with ca. 0.30 Volts, from an average of 14 to 13.7 Volts now.
Ideally, the minimum alternator charging voltage output should be 13.8, right? The battery is not yet 2 years old, but was not charged during the car`s 5 months hibernation. Maybe it needs a really long drive to be 100 charged?

JPG, I read about the "high current issue" before going for the alternator conversion last year. A guy at M&C Wilkinson talked about getting a buffer circuit to reduce alternator current, but my workshop told me not to worry as this conversion was tested and tried with no reported problems.

 

yeahh, that panel lights switch is famous, mine does the same thing if I do not exercise it.

bottom position is LIGHTS OFF
center position is LIGHTS DIMMED to about 50%
top position is LIGHTS AT MAX VOLTAGE.

is that how your is ?

 

Yes, exactly like yours, Jose.
But it is a slight exaggeration to describe the middle position as "light",
it is more like "not utterly & complete darkness" :-)
Top position is really useful when driving in the dark, though.
I will check the alternator charging voltage again next month.
If it is still dropping much further something may be wrong with it..?