G4 5761/7388 in Maglite 3C. Few questions.

Olumin

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Here is a shot of the 20W 7388 against a treeline across a field. The trees looks closer then they actually are due to the phone camera. Id say it was at least 200 meters (660 feet) but I cant be sure.
3C 20W.jpg

I dont have any other dedicated throwers, so just for comparison: Malkoff MD2 M61W 400 lumen. Predictably throw isnt that great. All 3 lights were aimed at the same Tree.
MD2.jpg

Surefire Fury 500 Lumen:
Fury.jpg

Much better throw with the Fury, obviously nowhere close to the MAG. 7388 is rated at about 500 Lumens, although on 2 Lithiums this should be brighter.

I wanted to do a 6Cell Maglite bulb shot but I still only have the frosted one at the moment to thats not really fair. 5761 will follow. Obviously this doesn't really show how far this setup can really throw but this is the best i can do at the moment. My guess would be around 400m (1300f) or at least approaching it.
 

vicv

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Nice. I may have to get one. I ordered the op one back in June. I'm still waiting for it to get here so I can try my tads 7218 bulb. Would be similar to a 7387
 

fivemega

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The 21700 15A cells seem to run the 7388 just fine but thats no surprise. 5761 are ordered and will arrive in a few days.
If your 21700 cells are protected, don't expect to run 5761 with first click.
I haven't seen any protected cell to power up spike of 5~5.5 Amps unless you have 2P/2S 18650 or 21700
 

Olumin

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5761 arrived. They power up on 2x Keeppower P2150R first click. Difference in brightness is not dramatic. Like vicv predicted due to larger filament throw is about the same maybe a little less then 7388. Close-up the increased brightness is more apparent. I am inclined to try the spring-bypass with desoldering braid and maybe ill get a bit more out of it. As-is I wouldnt say the upgrade from 7388 is worth it if throw is the priority.

As a side note: this time I let the new bulb run 10 minutes without head first and diddnt experience any fogging.

I currently have trouble uploading the image ill try again later.
 

Olumin

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As far as runtime goes: After total runtime on 7388 of ≈35min, and total of ≈20min on 5761, the protection circuit of the batteries kicked in and the light switched off. After turning the light off and on again it turned on but only dimly. Thats a generous total of about 1 hour. The batteries had become quite warm, I did not experience anything so extreme when running 7388. When putting the batteries in my charger they both initially showed 1% and voltage slightly below 3v (sadly my Fluke has yet to arrive in the post). I will continue to run 7388 for slightly better runtime but needless to say runtime will not be great. I will repeat this on 7388 only after a full charge and see what total runtime is.

For some some reason I diddnt think to check voltage with my cheap meter before throwing the batts in the charger. Oh well.
 

Olumin

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After having charged my batteries they blew both the 7388 & 5762 instantly... Thats even after having run a 6-cell bulb for a few minutes beforehand to "take the edge off". Im a little confused as this did not happen before. From what I read 7388 & 5762 should be fine on 2x li-ion and others have done so without problems. What am I doing wrong here? For how long will I have to run a 6-cell before I can safely use the halogens? I suppose that means I certainly can spare myself the trouble of doing a spring bypass.
 

vicv

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I'm surprised that happened with the 7388 but I did warn you about the 5761.
The reason why you're seeing this happen now but your research showed it works in the past, is because in the past we did not have excellent 21700 to feed the bulbs with. It was 2200mah 18650s and 6x eneloops. Your cells are not dropping nearly as much voltage.
I think you're going to need a soft start circuit. You can install a NTC in the tailcap. You definitely need to learn to solder though.
 

Olumin

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I'm surprised that happened with the 7388 but I did warn you about the 5761.
The reason why you're seeing this happen now but your research showed it works in the past, is because in the past we did not have excellent 21700 to feed the bulbs with. It was 2200mah 18650s and 6x eneloops. Your cells are not dropping nearly as much voltage.
I think you're going to need a soft start circuit. You can install a NTC in the tailcap. You definitely need to learn to solder though.
Yea I was curious about the NTC mod. What kind of NTC will I have to use and how will it be installed? Ive found my soldering gun. When it comes to DIY electrical stuff I need a bit of guidance tho.
 

Olumin

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I'm surprised that happened with the 7388 but I did warn you about the 5761.
The reason why you're seeing this happen now but your research showed it works in the past, is because in the past we did not have excellent 21700 to feed the bulbs with. It was 2200mah 18650s and 6x eneloops. Your cells are not dropping nearly as much voltage.
I think you're going to need a soft start circuit. You can install a NTC in the tailcap. You definitely need to learn to solder though.
What I found was:

Apparent the NTC that was used is: https://www.ametherm.com/datasheetspdf/SL121R010.pdf

I am still unclear on how to install it.
 

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