From: w.j.markerink@a1.nl To: dtlc@helios.net Date sent: Sun, 4 Nov 2001 12:22:01 +0100 Subject: [DTLC] Dimming 24V bulbs to 12V Send reply to: dtlc@helios.net Dear group, What would happen if I implemented a dual-voltage/power system to my headlights? Tentative Ingredients: - 24V H4 bulbs, 100/170W high/low beam - switching between 12V feed for 50/85W, vs 24V for 100/170W, depending on weather & traffic conditions (including the concept of daytime running lights at half the (max) power; as well as 'friendly' headlight flash at night, yet strong flash during the day). Just pondering....not sure what 12V would do to 24V bulbs in terms of durability.... -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] Date sent: Sun, 4 Nov 2001 06:53:08 -0800 (PST) From: mike_ayukawa@yahoo.com Subject: Re: [DTLC] Dimming 24V bulbs to 12V To: dtlc@helios.net Send reply to: dtlc@helios.net --- w.j.markerink@a1.nl wrote: > Dear group, > > What would happen if I implemented a > dual-voltage/power system to my > headlights? > Tentative Ingredients: > - 24V H4 bulbs, 100/170W high/low beam > - switching between 12V feed for 50/85W, vs 24V for > 100/170W, depending > on weather & traffic conditions (including the > concept of daytime > running lights at half the (max) power; as well as > 'friendly' > headlight flash at night, yet strong flash during > the day). > > Just pondering....not sure what 12V would do to 24V > bulbs in terms of > durability.... WJM, I think they would pretty much last forever at the lower voltage. Luminosity would drop by more than 4x, since the output would shift towards the red. Mike From: "Jeff Zepp" To: dtlc@helios.net Date sent: Sun, 04 Nov 2001 08:13:25 -0700 Subject: Re: [DTLC] Dimming 24V bulbs to 12V Send reply to: dtlc@helios.net > What would happen if I implemented a dual-voltage/power system to my > headlights? > Tentative Ingredients: > - 24V H4 bulbs, 100/170W high/low beam > - switching between 12V feed for 50/85W, vs 24V for 100/170W, depending > on weather & traffic conditions (including the concept of daytime > running lights at half the (max) power; as well as 'friendly' > headlight flash at night, yet strong flash during the day). > > Just pondering....not sure what 12V would do to 24V bulbs in terms of > durability.... Incandecent lamps do not have linear resistance to input voltage due to substantial positive temperature coefficient. That is, the hotter the filament, the higher the resistance. Thus, half the voltage input would yield considerably more than half the current (and power) as full 24 volts. Offsetting this, luminosity is non linear with power, half power will be considerably less than half luminosity. That said, you can't hurt anuthing running at less than full power, go ahead and try it out and see if the luminosity is sufficient. I would guess that half voltage input will not yield enough luminosity to be useful though. Good luck and happy cruisin'! Jeff Zepp TLCA #4063 From: w.j.markerink@a1.nl To: dtlc@helios.net Date: Sat, 13 Mar 2004 19:51:21 +0100 Subject: Re: [DTLC] high wattage 24v H4 Reply-To: dtlc@helios.net On 13 Mar 2004 at 9:45, stwalsh@uniserve.com wrote: > http://www.rallylights.com/hella/H4.asp Interesting site, never seen those most of the spec's before in Hella literature. Yet I wonder whether their insane low 'life' spec of 150 for the top- listed 24v H4 is for the 'standard' version, instead of 'heavy duty', as listed below as a second model. My 24v H4 bulbs definitely don't fail sooner than those in 12v vehicles, au contraire actually (might very well be that 'heavy duty' exceeds the '500' or even '1500' of the 12v versions). But this 'heavy duty' claim might be confusing on itself too, since not all other brands list it on the box, while the letters 'HD' sometimes *do* show up on the socket of the lamp....and Toyota doesn't make lamps, nor do all Toyota distributors or dealers sell lamps in Toyota boxes (not even sure whether such a thing exists). -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!]