Brightening the Headlights

[Charles Levien]

Hi Colin
Have you checked the voltage at the bulb? for a healthy circuit there should be hardly any drop in voltage.  You would find a distinct difference in upgrading to LED's, easily 100% brighter as long as your reflectors are doing there job properly.I was amazed at the difference front and back, well worth the outlay if you are doing a lot of night driving.You can always pop the normal bulbs back in for the purists. cheers.

The Ruby certainly lends itself to this conversion to LEDs as the front indicators share with the side lights and the rears fit into the pork pies. Heads are much brighter and you can take stress off the dynamo as you will need less charge. 
As has been said, you can retain the original bits for restoration to original at a later date but I suspect it won’t be you that does it.
One of the advantages is being able to drive with all lights on anytime you wish without having to cast anxious looks at the ammeter— this was useful to us when we did an extended tour a couple of years ago. It’s not so much about seeing where you’re going — more about other motorists seeing you’re there!

Charles ( currently in sunny San Francisco— sorry!)

[Colin Morgan]

Thank you for the advice - finally had a quick measure of voltages, but the garage is cold again today.

With an analogue voltmeter, the battery reads just over 6 volts - say 6.1 - of which about 5v is reaching the o/s headlight bulb contacts with the bulb removed, and the other light turned on.  As would be expected, the removed bulb is brighter when connected directly across the battery, but I can believe that new bulbs might be even brighter as the old one is not dazzling.  It must be at least 20 years old.  The ancient bulb holder contacts are a bit corroded - no longer shiny.

I have not yet checked the earthing voltage drop or seen if a direct earth back to the battery helps.  There is a return wire from the each light to a wing bolt.  It looks as if there may be some corrosion of the wire where it is trapped under the nut - so this might be improved.  The main earth cable runs from a bolt at the back of the starter motor to the positive battery terminal via a 'red key' isolation switch. However, there is no extra strap between the body and the rubber mounted engine.  There is no measurable voltage drop across the isolation switch - this is not so old, being a replacement for the one that failed without warning a few years back.  

When it warms up a bit, I plan to have a look point to point to see if the voltage drop is occurring mainly at a single location, or is accumulated through the various switches, connections and wiring.  

Colin

[Colin Morgan]

The light output from a bulb will decay as it ages, just fitting brand-new bulbs may restore their brilliance.

Just fitted new Lucas 6v headlight bulbs today - the old ones must have been in for donkey's years as I had never changed them - and, yes, the new ones are much brighter.  Thank you - good call.

Colin

[Bob Culver]

The original bulbs were only 18w and the charging system can safely match only this. Most now have much larger bulbs and especially with these if the battery is lowish the sytem voltage can dwindle below 6v. With the 3 brush system as volts dwindle so does the charge so get into a downward spiral.  If stuck far from home disconnect one lamp). Vintage car owners often report worse lights with larger bulbs.
For any who may be unclear, when measuring volts at some point of interest doing so under working conditons at that point is important. If there is no local current being drawn you are effectively measuring the voltage at some distant point. The 5v with other light on would be volts at switch output or any later last point of shared current (and somewhat low for whatever reason, esp for one lamp)
I ran my car with 6v 21w BPF motorcylce bulbs (vertical dip to upset the wof inspectors) but may not now be available

[Colin Morgan]

In this case, the bulbs that went in were the same wattage as those that came out - 30/24Watts - a standard type for the Lucas 7" reflectors often fitted to Rubies?

(As they will take 8 or 10 amps and the side and rear lights take up to an amp each more, the battery is, of course, needed to keep the lights on.)

[Colin Morgan]

Finally got around to checking the wiring (and voltage drop) to the still somewhat dim headlights (despite the new bulbs). Traced back from the lights to the dip-switch, ignition switch, through the ammeter and finally back to starter motor. Turned out that there was resistence at a poor joint where the wire from the starter motor went into the ammeter - this was obvious on inspection, as it had been running hot at high currents. The voltage seen at the dipswitch was only 5v with the headlights on. Fixing this has restored the headlights to a sensible brightness.

As it was me that replaced the ammeter years ago this was my fault, not Austin's! (However, I am not going to admit that I also discovered that all the dip switch did was swap the main beam from one side to the other - this is now fixed.)

[Bob Culver]

For purposes of tracing junction to junction voltgae drops it matters little if it is from 6v or 6.5 reference as measuring the drop and not the total. Much more constant with the motor off and no confusion from spark hash which Sevens generate like the Titanic radio transmitter. On many cars the dip switch was just to handle the momentary high but mostly low current of the solenoid reflector and is not suited constant filament load of rearranged systems. On the cars with focussable bulbs the beams can be "bright" but very sharp for modern roads with distant edges and marked lanes.

[Derek Sheldon]

I have on each of my cars, installed dedicated Earth returns directly to the battery for each and every electrical component.