Healey electrical issues.....

[goodwoodweirdo]

Hey guys,

Looking for a few pointers with my Healey 3000 … when I drive her for say 100mks at a steady speed, at night so with everything on the main electrical fuse blows, change it, drive 10 minutes and again.. leave her for an hour or two, let everything cool down and she’s fine again.. but during the day I can drive mixed speeds for hundreds of km’s no problems..

The car is fitted with an alternator conversion… so I imagine it’s the voltage regulator unable to handle the current … any other ideas?

Cheers
Matt

[Xerstead]

Do you have the headlights on during the day?

[goodwoodweirdo]

Sometimes....

I'm thinking its a draw of current and heat, not a short, however its always possible as the roads are crap here...

cheers

[Tony2or4]

The alternator should have a built-in regulator. The original regulator, which controlled the output from the original dynamo, should have been removed with the dynamo(and of course the associated heavy-gauge wiring modified to suit).

[john2443]

Are we right to assume the headlights run off the fuse that blows? Not sure why I ask that, but if they don't then it's not the headlights causing it.

Halogen heads or filament? Spots/driving lights?

The alternator will provide enough power for halogens but if it's the same amp fuse that was there for filament it might be running close to its limit. Not sure why it would blow at night but not in the day, but have you driven for 100k in the day with the heads on and mainbeam part of the time?

If the fuse it running close to full capacity maybe the temperature at night makes enough difference? No I don't know why, but anyone got a better idea!?!?

Clutching at straws slightly, but my daft questions might trigger a thought in someone's head.

[Hooli]

Aren't car fuses 'slow blow'? so they can exceed their current limits for short times but running with too much current for too long melts them.
I wonder if the alternator can produce more charging current than the fuse can handle?

[john2443]

Charging current should be going direct to the battery not through the fuse, but what you say may well have something to do with it.

[felixlighter]

Upgrade your main fuse (the one thats blowing)by 10% and see what happens, with everything switched on at night it may simply be working outside it's maximum design parameters. It will still blow if there is a short.