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High wattage H4 bulb currents


No_Twilight

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I posted long ago that I had bought some high wattage bulbs on ebay and when I installed them I would report the current draw. Last night I installed both the bulbs and the Eastern Beaver relay kit. I was very impressed with the kit, easy install, quality workmanship. It relieved me of all worries about the wiring harness. I wasn't impressed by the wires going to the headlight from the BMW harness (yes, I'm challenging the fine German engineering again). I think anyone who is planning to keep their bike long term should buy the eastern beaver kit. Melting a wiring harness in the middle of nowhere (it'll happen in the desert on a hot day, of course) would not be fun.

 

Here are the currents in amps. I had an Osram Bilux stock bulb to compare them to. The cheap e-bay bulbs say 100/90W and are blue in color and are in a package that says "Halo" on them.

 

__________________ Low ________ High

 

Osram _____________ 4.4 ________ 5.3

 

High watt_________ 6.1 ________ 6.9

 

--Jerry

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Melting a wiring harness in the middle of nowhere (it'll happen in the desert on a hot day, of course) would not be fun.
I've ridden my 1100RT with an 90/100 watt H4 lamp installed using the stock harness in 100+ degree temps all summer long for years without the slightest issue. A relay is probably advisable for getting the best lighting performance out of the lamp but as far as I can tell there is no real danger of damaging the wiring harness.
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Melting a wiring harness in the middle of nowhere (it'll happen in the desert on a hot day, of course) would not be fun.
I've ridden my R1100 with an 90/100 watt H4 lamp installed using the stock harness in 100+ degree temps all summer long for years without the slightest issue. A relay is probably advisable for getting the best lighting performance out of the lamp but as far as I can tell there is no real danger of damaging the wiring harness.

 

Smiler, I've had the same experience as you but there have been several instances of melted harnesses reported here. The problem is that one day if your harness gets just a little too hot it will get into a positive feedback loop--as the wire heats up the resistance of the copper goes up causing it to heat up more and more until it eventually melts. I don't know where that point is where the positive feedback loop starts so I worried about it when I didn't have anything else to worry about. smile.gif

 

--Jerry

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Don_Eilenberger
I posted long ago that I had bought some high wattage bulbs on ebay and when I installed them I would report the current draw. Last night I installed both the bulbs and the Eastern Beaver relay kit. I was very impressed with the kit, easy install, quality workmanship. It relieved me of all worries about the wiring harness. I wasn't impressed by the wires going to the headlight from the BMW harness (yes, I'm challenging the fine German engineering again). I think anyone who is planning to keep their bike long term should buy the eastern beaver kit. Melting a wiring harness in the middle of nowhere (it'll happen in the desert on a hot day, of course) would not be fun.

 

Here are the currents in amps. I had an Osram Bilux stock bulb to compare them to. The cheap e-bay bulbs say 100/90W and are blue in color and are in a package that says "Halo" on them.

 

__________________ Low ________ High

 

Osram _____________ 4.4 ________ 5.3

 

High watt_________ 6.1 ________ 6.9

 

--Jerry

 

Jerry,

 

That makes the Osram, a 56/67W and the "high Watt" a 78/88W bulb. With the blue filter coating on the high-watt bulb, it wouldn't surprise me if it puts out less light than your Osram.

 

Not a surprise actually - in testing bulbs for an article I did for the BMW Car Club of America - the blue "high-Watt" bulbs I tested invariably didn't meet their rating.

 

What would have been interesting is knowing the voltage drop between your bulbs and the battery. Based on the rated Wattage of an Osram bulb, I can back-figure you're seeing close to 12.8V at the bulb. If that's within 0.1V of your battery voltage, your Eastern Beaver headlight wiring is just fine (I have it on my K bike.. actually the very first setup Jim sold in the US..)

 

For more info on bulbs than you ever wanted to know.. http://www.bmwcca.org/members/AM/Template.cfm?Section=Let_There_Be_E36_Light - the hot setup IMHO for a bike is the euro Osram 50% more bulbs - these can be found on Ebay, or are available from http://www.powerbulbs.com in the UK (they ship to the US for free.. and quickly..)

 

Best,

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Melting a wiring harness in the middle of nowhere (it'll happen in the desert on a hot day, of course) would not be fun.
I've ridden my 1100RT with an 90/100 watt H4 lamp installed using the stock harness in 100+ degree temps all summer long for years without the slightest issue. A relay is probably advisable for getting the best lighting performance out of the lamp but as far as I can tell there is no real danger of damaging the wiring harness.

 

Seth,

I wouldn't be as worried about the harness as I would be about that flimsy Hi/Lo switch. I've seen 4 of them fail and it isn't pretty. smile.gif I predict (here I go again) that one day your headlamp will ONLY light up when you press the push-to-pass side.

 

Mick

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The problem is that one day if your harness gets just a little too hot it will get into a positive feedback loop--as the wire heats up the resistance of the copper goes up causing it to heat up more and more until it eventually melts.
I'm not aware of the existence of any such phenomena. Any resistance change of a copper conductor caused by a few degress one way or the other would be far too low to even measure much less affect the integrity of the wire itself. If a connection is poor for one reason or another in the switch or lamp socket then there could possibly be a problem, but certainly not in the conductors themselves, and probably not anywhere if the system is in any kind of reasonably good condition.

 

I predict (here I go again) that one day your headlamp will ONLY light up when you press the push-to-pass side.
Hmmm... after ten years of constant operation I guess that day should be coming soon... wink.gif
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Don,

Thanks for the data. I agree with your analysis.

 

I like your article you linked me to. At least my blue bulb is pulling more current than the one in the test so I hope it is making more light. But light output isn't important to me because I ride in So cal where all the roads are well lit and I don't ride much at night. In fact, I have no idea how long my headlight had been burnt out when I finally noticed it two days ago.

 

What I hope the blue lights do is make me more noticable with their unuaual color. Another test I want to do it sit it in the driveway side by side with a conventional bulbed bike and take a look at it.

 

Also the Ebay bulbs were dirt cheap--about $5 each.

 

I don't see the Osram 50% bulb in the test (or did I overlook it?). Is your recommendation based on testing or personal experience.

 

Looks like the link you provided to the UK seller is a better deal that available on ebay.

 

Thanks,

Jerry

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Looks like the link you provided to the UK seller is a better deal that available on ebay.

 

Thanks,

Jerry

 

I have made several purchases from Powerbulbs in the UK. They have very good prices, fast shipping, and bulbs you cannot find in the U.S.

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