Head Light Problem

[imacrazy]

I have a 6 volt alternator with halogen headlights, while the engine is idling the lights are dim.
When I rev the engine the lights are bright. What do I need to do to fix this problem?

Thanks for your input.

Bill

 

[TomInCologne]

Paul Shinn has posted a video on youtube about a 'zero rpm alternator'

 

[alexiskai]

The low-rpm alternator only solves the problem of the alternator needing to be excited before it starts charging. But even a normal alternator should charge at idle once excited. I wonder if it’s a low-voltage issue.

 

[Ted Duke]

Any light problem, ever, check your grounds. Don't ask me how I know. Seriously, check grounds to lights and to frame.

 

[AzBob]

Halogen bulbs draw a lot of amps.
My 55w halogen bulbs drew 4.4 amps each on low beam and this was on a 12 volt system. 6 volt system would draw more amps ~ 8A ea.

The issue is simply the alternator not spinning fast enough at idle to provide the required load at the required voltage.

Solution, switch to LEDs.

 

[alexiskai]

Might also try the Nu-Rex undersize pulley for more amps at idle.

https://www.nurex.com/alternator-pulley

 

[TomInCologne]

The low-rpm alternator only solves the problem of the alternator needing to be excited before it starts charging. But even a normal alternator should charge at idle once excited. I wonder if it’s a low-voltage issue.

"Zero RPM" Alternator for Ford Model A Cars is HERE!




https://www.youtube.com/watch?v=u6mh1TDA7I4

 

[AzBob]

Just because it is a "Zero RPM" alternator does not mean it will supply the load demand at the required voltage at the less than 400 rpm idle speed most Model A's run at. Smaller alternator pulley could help unless the OP already has one installed.

 

[Werner]

Hi Bill,

I turned a considerably smaller pulley for the alternator. (Oak wood with steel disc insert.)


So I already have plenty battery charging current at idle speed.

 

[imacrazy]

Thanks fellows, I found out some things that I will try.

Bill

 

[nkaminar]

The sockets in my halogen headlight were changed to accommodate the bulbs, so I cannot run the self-focusing LED bulbs without changing the sockets back to stock.

 

[Phil Brown]

Yes, a smaller pulley will turn the alternator faster at idle so that its output starts sooner and is a little higher. Rember your "A" idles probably around 400-500 rpm and the modern car that your alternator came from would idle around 800-850 rpm.

 

[Synchro909]

Sidetracking here and I hope most people already know already that when running a smaller alternator pulley, it is best to use a notched belt. They go around the small pulley more easily and last longer. Because the pulley is smaller, you will probably need a belt a little shorter than the original.