High output bulb for Maglite with 2 IMR?

[Mjolnir]

I recently "built" a 2D ROP maglite using 2 LiCo 18650s. I am planning on getting 2 4000 Mah 26650 LiMn (or IMR) cells from batteryspace. Apparently these will not destroy the 3854 low bulb, but their higher voltage off the charger will kill a 3854 High bulb.
One option would be the 7.2 Volt 3853 high bulb, but since it will not be overdriven as much as the 3854 would be, it wouldn't be as bright as a normal ROP high.
Apparently the Osram 64430 can stand up to the voltage. However, according to LuxLuthor's desctructive bulb tests, the estimated lumens are not very high for the 6-7 amps that the bulb is drawing, especially when compared to the 3853 High, which apparently draws about half the current at a given voltage, but has similar estimated output.

Also, my current reflector only has an 8.3MM opening. I am fine with getting a Bi-pin socket, but I'm pretty sure that many of the potential bulbs will not fit through the opening. However, the pins might, so is it practical (or recommended) to use a reflector with a small opening with a bi pin bulb (where the bulb body itself can't actually fit through), or is this a bad idea? I would hate to waste a perfectly good reflector, although I will get one with a wider opening if it really is necessary.

Are there any other bulbs that I should be considering for output equal to or greater than an ROP high bulb? I would like to keep the current draw under 10 amps, since that seems to be the limit for continuous draw for the cells. Also, it needs to withstand the voltage from 2 IMR cells fresh off the charger.

 

[R@ndom]

1111?

 

[Mjolnir]

It doesn't seem like the WA 1111 is any more tolerant of high voltages than the 3854-H is, at least according to the destructive bulb test info.

 

[R@ndom]

Resistor in tailcap spring mod?

 

[Mjolnir]

I would rather not do that, especially if I can get a bulb that will actually use the extra voltage of the cells.

 

[R@ndom]

Running out of ideas... Erm cell resting? Lctorana's graphs show that the 1274 should withstand 9 volts with good efficency.

 

[fivemega]

I am planning on getting 2 4000 Mah 26650 LiMn (or IMR) cells from batteryspace. Apparently these will not destroy the 3854 low bulb, but their higher voltage off the charger will kill a 3854 High bulb.

Are there any other bulbs that I should be considering for output equal to or greater than an ROP high bulb?

How about regulated 5761?

 

[Mjolnir]

I would prefer not to use a driver or regulator, especially since the cells are unprotected and I don't want to overdischarge them.

Part of what confuses me is this:
According the Luxluthor's lumens estimates, the 3853 H and 3854 L bulbs have very similar output at the same voltages, despite the fact that the 3853 draws 3+ amps, while the 3854 only draws 2, and at a lower voltage. However, the lux readings for the 3853 H bulb are almost double those of the 3854 L for the same voltages, which would seem to indicate to me that it is indeed significantly brighter. It also is much hotter according to the temperature, which might also indicate this. Basically, is the 3853 H bulb significantly brighter than the 3854 L bulb at about 8 volts? The numbers and estimates seem contradictory to me.

 

[fivemega]

According the Luxluthor's lumens estimates, the 3853 H and 3854 L bulbs have very similar output at the same voltages, despite the fact that the 3853 draws 3+ amps, while the 3854 only draws 2, and at a lower voltage.

We have very limited information about 3853 and 3854 bulbs.
There is no proof that 3854 bulbs are designed for 6 volts even if they are nominaly 6 volts.
These are designed to use with 3 cell lead acid batteries which may go up to 7 volts hot off the charger.
3853 is designed to work with 6 Nicad which is nominaly 7.2 volts but is the bulb designed for 7.2 volts?
Also we don't know designed bulb life which will indicate how hard bulb is working under certain voltage.
Lastly, 3853H and 3854H are halogen but 3853L and 3854L are Xenon and they act differently under same percentage of overdrive.

 

[LuxLuthor]

I would prefer not to use a driver or regulator, especially since the cells are unprotected and I don't want to overdischarge them.

Part of what confuses me is this:
According the Luxluthor's lumens estimates, the 3853 H and 3854 L bulbs have very similar output at the same voltages, despite the fact that the 3853 draws 3+ amps, while the 3854 only draws 2, and at a lower voltage. However, the lux readings for the 3853 H bulb are almost double those of the 3854 L for the same voltages, which would seem to indicate to me that it is indeed significantly brighter. It also is much hotter according to the temperature, which might also indicate this. Basically, is the 3853 H bulb significantly brighter than the 3854 L bulb at about 8 volts? The numbers and estimates seem contradictory to me.

As FM says, we really don't know much about the Pelican bulbs, other than label packaging. I answered your similar question with photo in the other thread comparing 3854 to 64430. Closeups of filaments certainly gives a better understanding for the differences, but it's not the whole story.

 

[325addict]

I would either try the:

WA 01274 (7.2V! exactly what you need) with a current draw of 2.77A and it throws out 553 Lumens then, with a life of 40 hours.

Alternatively, you COULD try the (now discontinued!) WA 01164:
This one is designed for 6 Volts, but has a very long life of 2500(!) hours.
It draws 3.28A and has "only" 301 Lumen this way.

Recalculating this for overdriving it on 7.2V:
Current draw about 3.6A
Output about 568 Lumen
life: still around 175 hours!

I would try that WA 01274 first, as this one is still readily available, AND it draws nearly 1 Amp less


Timmo.

 

[Starlight]

If you buy one of Jimmy's regulators, you can use any of the bulbs that have been mentioned, plus his regulator has a shut off for low voltage protection. You get the best of both worlds.

 

[ElectronGuru]

I've not yet made the switch to regulation and I love the 3853-H on a pair of IMR26500's. It stands up to 8.4 charger voltage without thought, offers screaming output for the size, and fits right through an 8.3mm reflector.

The thing to keep in mind is that overdrive is relative. 6.0v overdriven to 7.2 is the same amount of overdrive as 7.2v pushed to 8.4v. Its overdriving the 6.0 bulb to 8.4 that we get into trouble.

 

[Mjolnir]

I am thinking of just getting the 3853 bulb set for now, since it seems to work well. It will probably still be brighter than the 3854 H bulb with the 18650s that I am using, which probably sag a lot under load. If I am not satisfied with the 3853 bulb, then I suppose I could always get a 64430, or get a regulator and a 5671 or other bulb.

 

[ElectronGuru]

It will probably still be brighter than the 3854 H bulb with the 18650s that I am using, which probably sag a lot under load.

Yup. If IMR18650's are not blowing the 3854H, its because they are sagging - > reducing the overdrive factor.

I'm also quite happy with the 1185 on a -rested- trio of IMR26500's. These are about the top in output until you are ready to graduate to Orsams running 4+ cells (starting that now myself).

 

[Mjolnir]

I had been considering a Mag85, but my charger only has 2 bays/channels, so charging the cells would take twice as long. I also already have a 3D maglite, and I wanted something a little smaller.
Hopefully the 3853 will satisfy my brightness needs for now!

 

[Techjunkie]

I'm running a 5761 with an Amtherm NTC in the tail cap until my two Sony 26650VT (LiNiCoMn) batteries are down to 3.8v each, then I pop in a spring mod that bridges the battery -ve directly to the tailcap bypassing the NTC and direct drive's the bulb even brighter. Be careful though, more than 7.9V pops those $6 bulbs instantly.