Question for Lemlux on DB8AA

[Mr. Blue]

how long a time period have you used the light in operation with the current set up...I am curious about heat build up?

 

[lemlux]

Geoff:

I've run a total of about two hours on the setup, but I still haven't exceeded 5 to ten minutes per run. I now have a replacement reflector from my DB 6AA P91 conversion, so I think I'll walk a little further on the wild side.

I am encouraged enough about the DB's hear resistance that here's what I'm thinking of doing with one or more of my recently purchased DB 4AA's.

First, I'll run 6 123's in serial / parallel. (See recent posts in the DB 8AA string)

First I'll try my spare 13W 8 cell UKE bulb that is probably the WA 01171 that is rated at 9.60 V 1.33 amps 12.77 Watts 314.16 Lumens. At 8.64 V (the lowest level WA shows) this bulb draws 1.26 Amps (0.63 per cell) and generates 217 lumens. The voltage draw on this bulb with 6 123's will probably be lower than 8.64 V and may be an unattractive approach.

If I buy a bunch of WA bulbs (at least two per light) I'm tempted to try bulb #01274 designed for 7.2 Volts 2.77 amps (1.34 per cell) and 552 lumens with an extraordinary L/W rating of 27.7.

This 27.7 efficiency compares to only 16.7 =500 Lumens /30 Watts on the M6 with MN21. Brock says that the m6 with MN20 draws 7.2 V and 2.45 amps, so the 01274 bulb will probably draw closer to 7.0 V 2.74 Amps (1.37 A per cell) and 515 lumens.

The efficiency of the WA lamp compared to the MN21 is such that the the speced lumen output is the same on slightly less than 2/3 the wattage (19 vs. 30) and 4/7 the Amperage (2.7 vs 4.9) and wattage. Run time before battery exhaustion should greatly exceed the M6 HOLA as well.

This 19 watt WA 01274 isn't much more than the 16 watts I'm currently running successfully in my DB 8AA, but it generates considerably more lumens. The 19 Watt 6 @ 123 would make a poor man's M6 HOLA substitute useable for short periods assuming the amazing DB reflector and bexel continue to hold up. If and when heat distortion destroys it, all I've lost is a $7.99 light.

I wonder what aluminum replacement reflectors might be jury-rigged for the DB? I notice that Carley sells lots of reflectors in addition to their bulbs

 

[lemlux]

I've tried the 13 or 14 Watt UKE 8D cell bulb in a DB 4AA running 6 123's in serial / parallel. As expected, the voltage drop appears to be excessive. The light is much dimmer and yellower than the 18 W UKE 4 Cell bulb running in a DB8 8AA running 8 Nimhs in serial / parallel.

The 13 or 14 watt bulb is brighter and yellower than my 110 Lumen 8X and dimmer and yellower than my 140+ lumen Mag 4C with rechargeables and Carley KPR 1.7 amp bulb.

The 8 cell 14 Watt bulb is an inefficiently under-driven choice for the DB 4AA with this battery configuration. It would probably work well in a serial configuration with 3 123's in one barrel and 2 AA's in the other, but the drain on the 123's would be less efficient. The 123's would be drained much quicker than the AA's also. Nonetheless, it is an interesting way to get to 12 volts before voltage drop.

I'll have to wait before I convince myself to purchase $100 minimum bulb order from W/A. That point is approaching.

I think I'll have my second DB 8AA set up with Nimhs in serial and run the 14 Watt lamp there. It will obviously place less stress on the light than the underdriven 18 Watt bulb does in my current DB 8AA.