Isetta generator/ignition warning light bezel

[AndyL]

Okay, funny one this. The Isetta has three warning lights on the dash. Two of the lenses are cast in an acrylic type plastic and work as they should. The third used for the ignition/generator tell-tale has chrome bezel with a red insert that appears to be completely opaque. I have two of these, and they're both the same. Surely they couldn't have been like that from the factory- did they use a resin that went opaque with age or something? I can easily machine a new lens, but I'm just curious if any other Isetta owners have witnessed this?

[Bob Purton]

Mine has three matching lights, none of them the same as the one in the picture but I do have a spare dash board with that kind of light some where in the workshop, I will check it for clarity. Is your car a German one or Brighton built?

[AndyL]

Brighton built and Brighton registered. Definitely original equipment. I think the German cars had something different.

[Rusty Chrome (Malcolm Parker)]

Looks the same pattern as the ignition light on my Bond, but mine is translucent. I have seen some other completely different warning lights from the same period that looked opaque till you shone a light through them, but they were green and blue

[Big Al]

The plastic lens will fail under heat from an incorrect and to bright bulb. A bright 'un from Brighton might have had a bright one to be a bright one. Just as well the cars were not made in Portslade.......

[AndyL]

The light just about shows itself with the standard bulb. The led replacements I have for the main beam and indicator telltale didn't shine through on the generator warning light, but owing to the way this is wired in, I don't think an LED will work well anyway.

I've been going round replacing all the lamps with LED units, this has freed up about 25 watts, and is an easy job, as they just plug in place of the old filament based bulbs. The remaining lamps are the headlights. These are the trickiest, as no direct LED replacements exist that would look period, so I'm working on some units that will take the place of the lamps.

If I can get those working well, the lighting system should draw about 25-30 watts max. Sweet.

[DaveMiller]

Andy - a couple of things to watch when using LEDS:

Incandescent bulbs emit a wide range of colours, all adding up to "white", so there's always some light that can get through a coloured filter such as a red, green, etc light lens.
"White" LEDs don't emit a wide range of colours, but emit just a few specific frequencies, and those tend to be rather blue.  Such light will not get through a red or green lens!   If you have a red, green, amber, etc lens, then you need a red, green, amber, etc LED bulb.  (Take particular care with rear lights and flashers:  "white" LED bulbs may appear to show some light, but it will be HUGELY less bright than the same current running red or amber LEDs.)

On headlights, there are quite a few LED "headlamp" bulbs on the market which are absolutely useless!  If you see a whole "basket" of LEDs mounted on a headlamp bulb base, be very suspicious.  The reflector and lens of the headlight will be expecting the light to come from a specific, tiny location (the filament), and the light from, say, a 24-LED array will come from 24 different locations far from that ... sending out 24 different beams that shoot off in all sorts of directions, and not particularly down the road in front of you.

I've gone over to LED wherever I can on my two Bonds, but have yet to find anything available on standard bulb bases that does a decent job as headlight.  Luckily, the other LEDs save so much that I can now run incandescent (halogen) headlights full on, and still be showing a slight charge.

[AndyL]

Thanks for the advice. All the lights are coloured to their respective lens type, red for red, amber for amber etc. The exception was the dash lights, where I have used generic white, but no problems at all on those when testing.

For the headlamp bulbs, nothing on the market as you say, but emitters are available. The ones I have are 200 lumen per watt Cree XP-L LED's. These are available in various colour temperatures e.g. warm white which emulates a conventional filament lamp, neutral which is rather like Xenons and finally cool white, which is a very  blue white.

They can punch out up to 1000 lumens at full blast, although I don't plan to use them at that rate because they give best efficiency at lower wattage levels. The footprint of the emitter is tiny, about 3/16" square. So that should work pretty well I think with a parabolic reflector.

The plan is to use four per headlamp. Two mounted in the position of the dipped beam filament, pointing upwards, then two behind, one pointing down, the other up to mimic the main beam filament. The LED's can be dimmed using pulse width modulation, and adjusted to give good luminance whilst limiting the current.

[DaveMiller]

Sounds interesting, Andy - do let us know how you get on!

[AndyL]

Okay. Well here's a couple of high power units I'm working with, with a penny used for scale.



The smallest unit is the Cree XP-L, as you can see truly tiny, but capable of almost 1000 lumens (about equivalent to a 60 watt tungsten filament lamp), but gives best efficiency when driven to provide about half that luminance. The unit does need to be heatsinked, so my idea is to soft solder the underside where the heat pad is located to a copper skeg, which will also act as the location arm. this will then connect to a larger heatsink which will be located further back.  They need to be run with a 3volt regulated and current limited source.

The larger unit is a 10Watt LED runs at about 1000 lumens (lower efficiency than the cree, but still about 6-7 times better than normal lamp). This one runs on 10 volts, and there are nine LED dies within the footprint. It's much cheaper than the smaller Cree unit, and a lot easier to work with. I have a feeling these may not work as well in a parabolic reflector, but may give them a try all the same. They will work very well in the Isetta's small pod/side lights, and the aluminium housings make a ready built heatsink.