Negative experience with high-wattage low beam - BMW Luxury Touring Community
 
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post #1 of 5 Old Nov 14th, 2005, 7:29 pm Thread Starter
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Unhappy Negative experience with high-wattage low beam

Last year I installed a 70w low beam bulb. Today it burned out. A bit short on the longevity side, but more problematic was what I found when I wento change the bulb. The extra heat generated by this 70w bulb had caused the plastic that holds the two leads for the bulb to almost disintegrate. The spade connectors were almost welded to the lugs on the bulb.

55w bulbs look like the max for the low beam. I installed a Sylvania Silverstar bulb and subjectively it looks about the same as the 70w bulb.

I'm wondering now about removing the 85w high beam bulb. While the low beam is always on, the high beam is on much less. Not sure if there's enough heat for long enough to worry about with the high beam.

I toasted a car's headlight and had to replace the whole assembly a few years back -- EXPENSIVE! Anyone had a bad experience withan 85w high beam? I don't want to end up buying a new LT headlight assembly at BMW's prices.

Paul Browne
Reston, VA

'06 BMW R1200RT
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post #2 of 5 Old Nov 14th, 2005, 7:38 pm
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I ran 70 watt low for about a year, 30,000 miles, with no problems at all. I finally decided that was not enough so put in HID low beam. I ran the 85 watt high beam for the life of the bike, 4 years, 110,000 miles. Never had any problems with connections or housing overheating.

One of the keys is to use dielectric grease on the terminals. That keeps the terminals from corroding, making the connection worse and worse until the resistance gets high enough to cause heating.

The heating you saw was not from the bulb, but from higher than normal resistance in the connections. They either were not tight enough, or had started to oxidize, causing a resistance connection.

100 Watt bulbs however do over heat the headlight assembly, causing plasticizer outgassing, which clouds the reflector and lens, almost impossible to clean if it does.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
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post #3 of 5 Old Nov 14th, 2005, 7:56 pm
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Dave is right on with his diagnosis, I use dielectric grease on every connector I take off.

Brian Ley
WA State of mindless sheep
USA where everything is illegal
2007 K1200GT
2010 650GS
2000 k1200LT Sold but not forgotten
BMWOA 119892
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post #4 of 5 Old Nov 15th, 2005, 1:22 pm Thread Starter
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Thanks. I'll grease those connectors tonight and the rest as a winter maintenance project when the tupperware is off. The lugs and spade connectors were pretty ugly and I suspect that you're absolutely right that that was the cause of the heat.

Paul Browne
Reston, VA

'06 BMW R1200RT
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post #5 of 5 Old Nov 15th, 2005, 2:01 pm
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You may continue to have problems if the connector is already oxidized from overheating. If it is possible, I would clean the spades really good, and squeeze the slip-ons a little tighter, then push them on off a few times to burnish the contact surfaces. Make sure they fit pretty tight, then grease them.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
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