Maximum battery pack for 62138?

[^^Nova^^]

Hi,

I have checked out the graphs (thanks lctorana) and Lux's destructive testing and would like to know if I am on the right track or not.

I have a hand held spotlight that runs a 62138 bulb. I have run it off a 7ah SLA (12v) battery in the past, but it is quite dull so I would like to make it brighter. I would like to run a NiMH battery pack of decent capacity (sub-c or larger), and want to know what voltage to go before I will flash the bulb. The setup is very low resistance, one switch and bi-pin holder.

I assume a 14.4v pack will be too much (62138 flashes at 15v according to destructive data), so I will need a 11 cell 13.2v pack.

Cheers,
Nova

Actually, the other wild thought I had was swap to 64623 and run 14.4v sub-c pack. How would a 623 beam look in a 7" smooth reflector? The 138 is a beautiful round spot.

 

[TheInvader]

623's are 2mm larger than a 138, and the filament is a bit raised (I think) also.
Your output will be noticeably brighter, a bit less runtime, and floodier without focusing (shim)

 

[^^Nova^^]

Sounds like I may have to try a '623 and see what it looks like. I should have plenty of adjustment for the focus, I was just wondering how much a difference the horizontal filament would make.

If I like it then I can get the appropriate battery pack for the bulb.

Cheers,
Nova

 

[Starlight]

You need to spend the extra $40 and buy one of JimmyM's regulators. I also have hand held spotlights. I use his regulators because there is plenty of room and you never have to worry about voltage. A 62138 runs perfectly at 13.2v, at the bulb. You set the regulator for that voltage, then put in as many batteries as you want (up to 40v). The extra batteries just give you more runtime, but the bulb sees exactly the right voltage, never any blown bulbs. Use one regulator and you will never go back!

 

[^^Nova^^]

I have a regulated 5761 with one of Jimmy's regs. Simply amazing.

The only trouble I have with regulating this is the low battery selection. If I use car power (13.8v running, 12.5v engine off) and also NiMH batteries then the low voltage setting is going to be different for the battery pack than the car. Although if I go with 12 cells that gives me 12v low battery, may not be too bad, only rules out small SLA batteries (I think they would sag to less than 12v fairly quickly).

Cheers,
Nova

 

[Starlight]

I don't bother to try and set the low voltage cutoff to shut off the light. I do it the old fashioned way. I set the low voltage so low that it doesn't do anything and I turn the light off myself. It is more problem to me than help.