12 volt automotive sealed beam lamps in series

klem kedidelhopper · 2011-01-04T18:08:03+00:00

I have a 24 volt military truck that I use for snow plowing. In thepast I've had trouble finding 6000 series 24 volt sealed beam lampsfor the plow frame.. And when I did I have found them to be veryexpensive. So I came up with a circuit using a DPDT switch in whichboth the high and low circuit lamp filaments are wired in series whenpower is applied. I was very careful to initially select two lampsthat drew exactly the same current when tested on my bench powersupply. The arrangement has worked flawlessly for the past few years.The other night I had occaision to look at the lights from outside thetruck while it was running. Charging voltage on a 24 volt system canrun as high as 28 volts on a typical 24 volt system. Although I didn'ttry to measure the voltage accross each lamp, I noticed that one lampis slightly brighter than the other on the low circuit. I'm assumingthat filament is getting weaker and thinner and will likely failshortly. And of course when that happens I'll lose the low circuit. Ican rematch two more lamps but before I do the thought occurred to meif there was any practical easy way the equalise the voltage accrossboth lamps in order to compensate for any minute differences infilament resistance. I think that the total current, (two lamps inseries) is about 5.0 amps. Thanks for any suggestions. Lenny

Jan 04, 2011 25 Replies

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Michael A. Terrell 15 years ago

Probably, but it's 14 years old and I've not spent more than $100 in repairs in the 3 years I've owned it. :)

You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated.

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Michael A. Terrell 15 years ago

As a guest? Probably.

You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated.

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Spehro Pefhany 15 years ago

Okay, then, if $170 is too much, how about $7.56 including shipping?

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They also have 15A/20A for 14.89/16.42 including shipping.

Best regards, Spehro Pefhany

"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

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Spehro Pefhany 15 years ago

Or this one for $11.72 shipped which is claimed to be 20A

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Best regards, Spehro Pefhany

"it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com

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Angelo Campanella 15 years ago

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I'd go for that in a heart beat. you could set it in series with the fuse feeding the head lights.

I'd get two; one as a spare since you have NO idea of its practical service life in a road truck and you'd like to have a spare along.

Later, if #1 proves flawless, use #2 for the tail lights and swap them out too when called for...

Ange

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Michael A. Terrell 15 years ago

That would be good for people wanting a car radio on a 24 v golf cart. :)

You can't fix stupid. You can't even put a band-aid on it, because it's Teflon coated.

Vote

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