Want to use Phillips 5761 bulb- dont want blown bulbs: how to set up?

What is a nice, easy to set up way (minimal soldering) of building a 5761 based light? Would like to go with either 18650s, AW IMR C cells and AAs, in that order of preference. Might use AW's soft starter (wish there wasn't the dimming modes), unless there is an easier way. Would like to keep internal resistance to a minimum.
Thanks!

If you used 2x A123's or LiFePO4 batteries I don't believe you would need a softstart at all. Is that an option?

Yeah, LiFePO4 cells won't blow the bulb. It won't be a bright as possible, but still plenty bright.

Batteryspace has some available in differing sizes.

Deck out a 2D mag with a KUI socket and you should be good to go (along with reflector and lens swap).

Cheers,
Nova

What is the proper charger for them? Thanks

To be honest, I am not entirely sure. I have heard some reports that regular Li-ion chargers work fine, although it seems setting the charger to 4.1v termination not the normal.4.2v is better. There are proper LiFePO4 chargers around though, this may be a better option.

I would find out a definite answer before purchasing anything though.

Cheers,
Nova

Is there a switch with soft start only? (I'll get the AW if theres no other way)
Now to decide if I want the compact 2C size or the 2D size

I have a 2c 5761 powered by two 26500 lifepo4's and it will never blow the bulb. The problem is it doesn't even drive it to specs. I measured 6.4v at first turn on and 5.7 after 1 min. I didn't check to see where it stabilized because I was so dissapointed already. This bulb is really shines when overdriven and I'm already planning a build with a regulator to push it to the max.

There is the JM-PhD-D1 PWM Hotwire Regulator.

Other than that you could try using an NTC. Northern Lights did some work with them and found that there can be a lot of variation from component to component. Still, it has been done. Of course, there is always a power resistor. They waste energy, but they work!

If you use LiCo 18650s you really don't need soft start, but you can't use protected cells either because the current draw is too high and trips the protection circuit. You would have to use high quality cells like LG.

If I was going to use 18650, I'll do IMR, which means POOF
I wish I could install a second switch that cuts in a resistor to start it before giving it full power

That is sort of how NTC's work. They offer more resistance when they are cold and the resistance drops to almost nothing when they are hot. There are some threads on using them, but most of them were for AW C cells (LiCo) with the 5761. I would contact Northern Lights for recommendations pertaining to the use of IMR 18650s with the 5761. This may be one of those situations that also requires the use of a resistor in combination with the NTC to get it working, but you would spend a lot less than on a regulator or AW soft start, it would not have a delay like the AW switch, and it would be pretty efficient too. You already said runtime was not a concern, so I assumed a resistor solution was acceptable.

Runtime is not a concern, though I do want maxiumum "safe" brightness

Anyone else using LiFePO4 cells? Curious about how bad the under drive is

So if I use IMR 26650 cells in a C M@g, it'll be a tight fit or will I need it bored out?
If I use 18650s, do I need to sleeve the batteries?
In both cases, I'll need to mod the tail cap spring in some way or form, right?

GarageBoy said:

If I use 18650s, do I need to sleeve the batteries?
In both cases, I'll need to mod the tail cap spring in some way or form, right?

Click to expand...

You don't have to sleeve 18650s, I've got one without a sleeve. I'll probably end up sleeving all 3 of mine before it's over, if for no other reason than to keep the cells from rattling.

For 2 18650s you'll need to deanodize the tailcap. I used a dremel with a grinding stone. All you have to do is work it til you see bare aluminum. Then you'll need something to make contact between the tailcap and the batteries. I've used a minimag tailspring for my lights.

I don't have anything currently running a 26650 so I can't answer about them.

oops, I meant 26500 IMR

Love the IMR26500, but won't fit in a MagC.


2x18650 is a typical setup for a MagC. And as you can get the AW p26 cells, you can get more capacity out of them then the IMR cells.

I would recommend the WA1111 or ROP bulbs.
Both are configs you can run in a 2C with the 18650 without an Incan Driver and without

Also, there are more reflector options for the Rop and 1111.

Sleeving the batteries is recommended, and really easy. You can make a decent sleeve out of papertowel tube and electrical tape.

THIS CHART will give you a good idea what a 5761 can handle.
Seems you'll gain a good 700 lumens going from Lifepo4 to Li-ion.

As the bulb flashes at 7.9v you'll def need a softstart to run it off 2 Lions. And at 5+ amps it will exceed the P-26 output ability.
Are you sure you want to go 5761, it's a much more complicated build?
A Rop54 High will rival its output, and according to THIS CHART you SHOULD be able to build one with the P-26 cells and without the need for a softstart.



If you are willing to buy a softstart, you could go Mag85 in a 2D with 3xIMR cells. This would be the best config in my opinion for that output level. And I've personally tested it.


Within the next days I'll be writing up a Rop/11 tutorial, and a tutorial for easy sleeves.

I dunno how much you're after a hot Mag61, and how much you're after the experience of building one. If it's the former, Northern Lights has an absolute steal right now.

The other option for a 5761 in 2C is the DX 25500 -- actually capacity is 3Ah or so, so no worries about overdischarge, and it fits easily in a C Mag. You may need a shortened tailspring; I'm using a special shortened and widened tailspring that lets me run 2x18650 (down through the spring, into a copper-braid-over-foam contact in the bottom of the tailcap) or 2x25500, with the 2x18650 obviously being intermittent duty only.

I have this setup, and have run over 10 hours with only one burnt bulb. No soft-start, but also no real resistance fixes. I started with a stock switch and cammed reflector, but eventually (as a result of an hour continuous burn) the focusing spring annealed and collapsed, and the switch was somewhat melted; when I replaced the switch, I used a steel braid from cheap TV cable to bypass the spring, in fears that the usual copper bypass would blow bulbs.

I want the extra brightness of the 5761, but I like the 2C form factor
Will the 18650-26 light up the bulb, or will it blow?

I just acquired a 2C Mag with a 5761. I've been running it on 2 unprotected 2600mAh Samsung 18650's with no

As mentioned before, you'll need to make space in the tailcap, and there are a few options for that.

It has a Kiu socket, and no resistance mods.

GarageBoy said:

I want the extra brightness of the 5761, but I like the 2C form factor
Will the 18650-26 light up the bulb, or will it blow?

Click to expand...

I haven't tried with AW's newer cells, but would be willing to bet that the 5761 would trip the protection circuit, hence the use of unprotected 18650s for the 5761. That is of course a riskier approach and pushes the cells to their absolute limit.

mvyrmnd said:

I just acquired a 2C Mag with a 5761. I've been running it on 2 unprotected 2600mAh Samsung 18650's with no

As mentioned before, you'll need to make space in the tailcap, and there are a few options for that.

It has a Kiu socket, and no resistance mods.

Click to expand...

Just a little follow-up: I killed my bulb.

Turns out a full charge of the batteries was too much to take...