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Author Topic:   Spotlight: Short Bulb Life
montaukman posted 10-12-2005 12:30 AM ET (US)   Profile for montaukman   Send Email to montaukman  
I have gone out a few times at night using both a new 1,000,000 [something] and a new 2,000,000 [something] spot light, and, within five minutes, I have blown the lights each time. I was careful not to keep [the spotlight] on for more than 30 seconds at a time, yet I still blew them both.

Is it common for [spotlights] to go this quickly? The spotlight has a separate courtesy light built into it, and that still works so I know I am getting power.

Any suggestions? [Is there anything related to the 170 MONTAUK boat which affects this situation?]



ASIDE: I was fishing at about 3 a.m. and saw tremendous luminescence from my wake. When I dropped my lines, the water gave off a phospherous blue/green light as I moved the line in the water or disrupted it in any way. It was amazing and I am told it is from algae. Didn't catch any fish but it was a sight to see. Anyone ever experience this?

RocketMan posted 10-12-2005 01:42 AM ET (US)     Profile for RocketMan  Send Email to RocketMan     
Interesting about blowing the lights. I would imagine your engine alternator is powering a buss bar that is distributing power to various accessories, including the plug you mention. It would seem that measuring its voltage output would provide some insight. A reading near 12-volts would seem normal and if abnormal, other problems could develop in the system. If normal, then somehow you're drawing too much current and I would study how that plug is wired up as well as the light power requirement vs. the rated plug output. I usually clip my light right to the battery posts and have noticed that the wires warm pretty good, so they draw a relatively large wattage vs. your other 'lectrical components.

Also, its possible the lights were defective in some way? Plugging a light in and having it burn out in a very short time usually indicates to me that the vacuum in the bulb is lost and the filament is burning brightly in the air volume. This would signficantly shorten its life resulting in rapid failure. Just a hunch. Good luck.

ASIDE: I've seen the luminescence crossing the Gulfstream at night in sailboats. Kind of 'spellbinding' for a landlubber the first time you see it. I believe that swordfisherman utilize that principle with luminescence sticks to attract the fish at night.

Sheila posted 10-12-2005 04:29 AM ET (US)     Profile for Sheila  Send Email to Sheila     
Hi Alan,
Good to hear from you! We've been wondering where you were (there's a post in the Meta Forum asking your whereabouts)...

We have a number of 12v DC rechargeable spotlights that can be run either from their own battery or with a 12v accessory adapter. We've never blown a bulb on either of our boats. I don't know how to tell you to test the accessory outlet on your boat.

ASIDE: The blue-green color you see is called bioluminescense (maybe I spelled that right). It is an amazing sight, one I never tire of seeing.

poker13 posted 10-12-2005 09:54 AM ET (US)     Profile for poker13    
Could it be that the bulbs were very hot and were cracked by a splash of cold water?
Chuck Tribolet posted 10-12-2005 04:45 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
RocketMan has it right. Measure the voltage. It should be
about 13V with the engine running.

It's NOT the socket. The socket could make the voltage lower,
but not higher. I'd guess voltage regulator, or real bad


swist posted 10-12-2005 10:14 PM ET (US)     Profile for swist  Send Email to swist     
With the alternator running you've probably got closer to 14 volts than 12 at that outlet, but on the other hand most accessories, spotlights included, are usually designed to work over a broad range of voltages (11-15, for example).
jimh posted 10-12-2005 11:13 PM ET (US)     Profile for jimh  Send Email to jimh     
If the lamp has an incandescent bulb, it is probably failing due to too much voltage being used.
Dick posted 10-13-2005 07:45 PM ET (US)     Profile for Dick  Send Email to Dick     
If the only thing your are blowing is the spotlight, and the navigation lamps and other electronics are OK, I would would say that the spotlights are not up to quality and it is not an engine problem.
davej14 posted 10-13-2005 08:05 PM ET (US)     Profile for davej14  Send Email to davej14     
If you are getting 1 or 2 million candle power with an incandescent bulb at 12V it would be called a flash bulb and that would be your problem :-)

I vote for just bad luck or an out of control voltage regulator circuit, which should be pretty easy to test.

HawaiianWhaler posted 10-14-2005 07:01 AM ET (US)     Profile for HawaiianWhaler  Send Email to HawaiianWhaler     
Just out of curiosity, what make/model spotlight? Maybe I won't buy one of those after all ;)
swist posted 10-14-2005 05:52 PM ET (US)     Profile for swist  Send Email to swist     
I would note that most modern electronics and other devices use solid state voltage regulators that can accept a really wide range of input voltage (like 9 - 20 volts). This includes the ECM in the engine as well as stereos etc. So you could have a serious regulator problem and never notice it until you hook up a low tech device like a light bulb.

Your navigation lamps are also designed to operate on more than 12V, but if you are regularly [operating them at] over-voltage then their life will be reduced.

jimh posted 10-15-2005 01:16 PM ET (US)     Profile for jimh  Send Email to jimh     
The life span of an incandescent lamp is very much related to the voltage at which it is operated. If the voltage is too high, the lamp will draw excessive current, creating excessive heat which ultimately burns out the filament.

Also, the filament in the lamp is very fragile when it is hot. You must be careful when handling a high-intensity lamp like a spot light. Any mechanical jarring can damage the lamp.

As others have suggested, the power distribution system on your boat is quite simple and there is no reason to believe that the power available at the accessory connector on the 170 MONTAUK is in any way different than the power available at the battery. If there is a problem with the engine voltage regulator, it would affect the power at the accessory connector.

One thing about the connector and the connection which could affect the lamp is any electrical intermittent connection. Interrupting the power to a high-intensity lamp and quickly restoring it can cause damage. Check that the connector is firmly seated and there are no loose connections.

[This discussion was moved from another area.]

where2 posted 10-15-2005 10:39 PM ET (US)     Profile for where2  Send Email to where2     
If you remove the 1,000,000 candle power bulb from the lamp, you will probably find that it is a typical H3 or H1 bulb rated at 55w or 100w. Do yourself a favor and replace the bulb with a Hella bulb from your local auto parts store. H3 bulbs are generally used in automotive fog lights, and H1 bulbs are used in some high beam applications.
RocketMan posted 10-16-2005 08:08 AM ET (US)     Profile for RocketMan  Send Email to RocketMan     
Agree with the fragility of the filament point. I've lost a couple of spotlights to 'handling' when filament was hot. They seem to burn a lot hotter than a run-of-the-mill automobile headlight so the recommendation to go with one that is designed for automotive application seems like a good one.
montaukman posted 10-23-2005 07:47 PM ET (US)     Profile for montaukman  Send Email to montaukman     
Hi everyone.

Well, i found the culprit to my spotlight problem.....seems the connection at the trigger was lousy. The factory spotlight (West Marine) was faulty in that when you pressed the trigger, the switch was not making contact with

I bent the plate on the switch so that there isn't as much trigger travel required and all is fine now.

Lousy design if you ask can all rest easy as I know this dilema was keeping you up at

Thanks for you help in offering suggestions. Wonder who makes this for West Marine.

All the best,


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