I instaflashed a ROP bulb

Bummer. I built a 7C ROP in an old Mag 6D body. I'd been running the low output 11W SLA ROP bulb in this Mag on 6 alkaline D's for a while with the stock reflector for short runs only, but was itching for more power. So tonight I finally got around to cutting some 1" PVC and dropping in 7 NiMH C's for better performance (should be much less voltage sag, for better final output). Looked GREAT with the 11W bulb, so I dropped in a 24W high output ROP bulb and it instaflashed! D'OH! These cells are fully charged, but rested for a couple days. No load voltage at the bulb holder measures 9.8 V. I put the 11W bulb back in and it's working great. The 11W bulb with 7 C's is brighter than my 2D Mag ROP with 6 CBP 1650's in a fivemega battery holder drivning a 24W bulb.

Kinda weird that the low ouput bulb handles the overdrive better. Maybe I got a bad 24W bulb? Has anyone else successfully built a 7 C cell 24W ROP?

This is my truck light for now. Next step is drilling out my FM SMO cammed reflector to fit the over the bulb, as I want it to be a throw monster....

From what I have been reading while waiting for my bulbs to show up (3854's) and getting the rest together (need to pick up a glas lens still!) I am going to follow recommendations and go with 6 AA Nimh's. The 7th cell is the problem I believe because from my research 6 cells id the formula for a reliable light. Hope this helps.... someone tell me if I am mistaken please and why. Did a search for ROP and came up with a few good threads for lithium model and such, but one said 6 c half cells, or 6 AA's. Thanks.

I been running 7 AA on ROP with three of my flashlights without a problem. Perhaps the AA have more voltage sage than your C size batteries. :shrug:

Hey Yooper, sorry I can't help with your problem, I'm still kinda new to all this stuff, but something in your post has me confused. You said you need to ream your FM reflector so it fits over the bulb. The reflector should have an 8mm (.315") opening, roughly the same size opening that modamag is advertising in his reflector group buy. modamag said the Big D bulbs are compatible with his reflector, why wouldn't they fit in the FM relector if it has the same size opening.

Can you measure the diameter of a Big D bulb for me?

I run 7 Aero 1/2D cells good for 20+ amps and the 24 watt lamp. It rocks!!

From what I have read and my observation of the filaments, the Low output lamp looks more fragile. It does run VERY nicely on 2 LiIon 18650's.

Bill

i am currently running a 6D mag on a WA1274 potted bulb and 7c nimh. How much brighter would the ROP make it? Is it potted or do i need a bipin adapter? and will it fit in the same hole as a WA bulb?

Flakey said:

i am currently running a 6D mag on a WA1274 potted bulb and 7c nimh. How much brighter would the ROP make it? Is it potted or do i need a bipin adapter? and will it fit in the same hole as a WA bulb?

Click to expand...

From what I gather elsewhere in this forum, the WA1274 on 7 cells will give 618 output lumens while the ROP HOLA will give 550-600 output lumens so I guess they are pretty close.
The ROPs are potted.

The 3854 Big D "ROP" 11W bulb is .300 inches (7.62mm). The hole in my FM SMO cammed reflector (ordered from this thread: https://www.candlepowerforums.com/threads/102857 ) measured .290 inches (7.37 mm). I drilled it out in a few seconds with a drill press to .325 (8.26mm) and now it fits great.

Maybe I got a bad 24W bulb, or a particularly robust 11W, or these are particularly hot batteries (Titanium 5000 maH C's). I'm reluctant to try another 24W.

With the 11W bulb on 7 cells the beam is VERY white. Whiter than my 24W bulb in my 6AA ROP.

I have no experience with 1274, but I put a potted 1111 in my 6AA light and the 24W ROP bulb blew it away.

I'm thinking of switching to 6 11,0000 maH Titanium D's in this light with the 24W bulb for better reliability. 6.6 aH of battery capacity should give me a decent runtime!

Thanks for the measurements. I'm getting a reflector from modamag and planned on using FM's hi-temp socket with bi-pin bulbs, but he's sold out of them, so I'm just going to run Big D bulbs for now. At least now I know they'll fit.

I'll probably buy a pack of 3854's rated at 6V and a pack of 3853's rated at 7.2V and see if there is any difference in performance. I'll be using 7 or 8 NimH AA in a 2D host. First super light for me, so the learning curve is real steep.