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>On Fri, 8 Sep 1995, GEORGE M IRVINE III wrote: > >> A friend of mine asked me about backup lights. I use >> two, Oceanic 3 - c battery "hilites". The trick to backup lights >> is no rechageables, use the 3-c battery lights, and make sure that >> the voltage of the bulb matches the combined voltage of the >> batteries. Check the batteries - some manufacturers think they >> are doing you a facor to pump the voltage up to 1.6 - too much. >> If there is not a match, go get new bulbs. If you can't get the >> right >> bulb, don;t use the light. Another nice feaure is that they have >> an attachment pint at the end of the cannister. If you are using >> Princeton Tec lights , for example , change the bulb. If you >> are using those little Q 40's , throw them away. - George > >George, what do you think of 4 C cell lights like the Ikelite Mini C's as >backups? How about the ACR Firefly Plus as a third (Fourth) light? Combo >lame light for jams, and a strobe, small enough to stash easily, light >and good as a surface marker? (Available at Boater's World.) > >What are your sources for bulbs? You seem to be able to get a wider >voltage range than I can - I'm interested in where you get them? I feel >like I'm stuck with what the manufacturer gives me. > >Nick Simicich The "correct" voltage rating (itself a compromise between maximum expected life and color temp. distribution of the light emitted) will depend on the types of batteries used and the current drawn by the filament. High currents and alkaline batteries don't go well together (Lithiums don't like high currents either). NiCds and gelled lead-acids are way better in this respect because of their low-internal impedances: the terminal voltage remains about the same irrespective of the current drawn. It's hard however to to beat the alkalines in capacity: You'd be hard pressed to find NiCds of the C persuation push much above 2.5 Ah at 250 mA discharge currents. Also, rechargeables demand more care and insight into such issues as proper charging, discharging and storage. We slugged out the alkaline vs. NiCDs debate in Scubal-l not long ago. With the above information in hand you might have luck picking lamps from the following table (created and distributed by Willie Hunt for a PWM controller he created): bulb volts amps watts ohms HPR36 Halogen 5.5 1.00 5.5 5.5 K-18 Krypton 7.2 0.7 5.0 10.3 HPR50 Halogen 5.2 0.88 4.6 5.9 HPR51 Halogen 6.5 0.70 4.5 9.3 HPR40 Halogen 6.0 0.67 4.0 9.0 K-12 Krypton 6.0 0.65 3.9 9.2 HPR53 Halogen 4.0 0.85 3.4 4.7 K-15 Krypton 4.8 0.7 3.4 6.9 605 Vacuum 6.0 0.5 3.0 12.0 K-3 Krypton 3.6 0.8 2.9 4.5 HPR41 Halogen 3.75 0.75 2.8 5.0 425 Vacuum 5.0 0.5 2.5 10.0 HPR52 Halogen 2.8 0.85 2.4 3.3 Petzl Halogen 3.75 0.5 1.9 7.5 K-2 Krypton 2.4 0.8 1.9 3.0 PR-3 Vacuum 3.57 0.5 1.8 7.1 K-1 Krypton 2.4 0.6 1.4 4.0 K-222 Krypton 2.33 0.6 1.4 3.9 PR-2 Vacuum 2.38 0.5 1.2 4.8 K-4 Krypton 2.33 0.48 1.1 4.9 Petzl Vacuum 3.75 0.22 0.8 17.0 243 Vacuum 2.33 0.22 0.5 10.6 Don't snort at the Kryptons. In actual use you might find the Kryptons plenty bright. john
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