Eco & Long-Life Bulbs - pmh2
Taken directly from an advert by a reputable manufacturer.

Eco & Long-Life Bulbs designed to use less power and have a longer life
H4 Philips EcoVision 12v 60/55w NEW! (pair)

EcoVision consumes up to 20% less energy than a standard car lamp while giving you twice the lifetime and 10% more light.
Price: £14.89 (inc. VAT)
RRP: £25.99 | Save: 43%
Taken directly from an advert.

Anybody care to explain how an eco bulb rated at 60/55W uses less energy than a standard 60/55W bulb?

A triumph of advertising over reality?

Eco & Long-Life Bulbs - J Bonington Jagworth
I think it's typical marketing spin. I sort of know what they mean, in that it has to have 60/55W (not too sure what that means, though) on the packet, but that it is actually using fewer watts while delivering more light. We have some halogen replacements for 40W indoor light bulbs that actually consume 28W, but as what you want to know is where to use them, they have both values on the packet.

I'm not sure that saving 12W per headlight is going to make a big difference to your fuel consumption, though...
Eco & Long-Life Bulbs - Hamsafar
Just looked at the Philips website, nauseating marketing cods-wallop.
Eco & Long-Life Bulbs - oldnotbold
Does it really make any odds that a car light bulb uses 20% less - I've never yet had anyone round to read the meter on my car, or received a bill for the electricity.
Eco & Long-Life Bulbs - Old Navy
Just looked at the Philips website nauseating marketing cods-wallop.

I like the help save the planet by using EcoVision bulbs pitch, lit by a 100+bhp powered alternator ?
Eco & Long-Life Bulbs - J Bonington Jagworth
"help save the planet"

Makes one wonder how the marketing men get around. Surely they couldn't be that insincere..?
Eco & Long-Life Bulbs - Red Baron

If you reduce the diameter of the filament the resistance increases and so the light emitted is 'hotter' (10% more light), and if you reduce the filament diameter even further and make the filament from even purer metal then less energy may be required to give you the same 'hotter' light.

However, a thinner filament that glows hotter requires a much purer (i.e. oxygen free) environment else it will oxidize rapidly, become brittle, and break. Which in reality is what is going to happen anyway considering the thump and crash that all cars are subjected to these days.

Eco my foot!
Eco & Long-Life Bulbs - L'escargot
It's probably just that the advert was composed by someone who doesn't realise the importance of being precise when talking about technical matters. I don't suppose there was any intention to deceive. I imagine the reality is that the bulbs give out the same light as conventional 60/55W bulbs, but don't actually consume 60/55W of power.

Incidentally, if you copied the advert word for word then the composer isn't aware that the unit of power is capital W (because it's named after an individual, James Watt) and not lower case w.

Clearly, the advert was composed by a marketing person not a qualified electrical engineer.

Edited by L'escargot on 19/03/2009 at 07:23

Eco & Long-Life Bulbs - pmh2

Well spotted. However I think that you have actually solved the mystery. The W is the official unit of power named after Watt - the w is actually only 90% of a W - named after w******(william?), the marketeer who launched the capaign for Phillips.

Makes the whole advert technically correct.

Eco & Long-Life Bulbs - madux
I thought that alternators produced the same output whatever the load, and that heatsinks are there to dissipate the excess?
Eco & Long-Life Bulbs - Hamsafar
"I thought that alternators produced the same output whatever the load, and that heatsinks are there to dissipate the excess?"

- No, there are no heatsinks, the output depends on the load, that's why if you turn on a rear heated screen, you may here the idle speed drop for a split second.
Eco & Long-Life Bulbs - J Bonington Jagworth
"there are no heatsinks"

There can be, but if so, they are only there to help dissipate heat from the generating process (itself maybe 80% efficient) and/or the rectifiers that turn the output into usable DC and which have to handle quite a lot of current - they're not 100% efficient either.

Hamsafar is quite right that only the current required is drawn. Just as well, really!

Edited by J Bonington Jagworth on 19/03/2009 at 19:59