Boost driver to power an MC-E? Would this work?

[PCC]

I've been thinking of modifying a pair of 2D MagLites that I have for my kids to use. I want to keep the battery chemistry safe for them to use so I have decided to use NiMH batteries because I have a bunch of D NiMH cells already. The problem is that I ordered a pair of MC-E emitters without really thinking about where to use them. The thought occurred to me that it might work to power the MC-Es if they're wired 2S2P with a boost driver intended to be used with a single emitter like a Sandwich Shop Mad Max Plus or BB Nexgen 750. Would I blow up the driver if I tried this?

Also, I tried applying power momentarily to an MC-E that is wired 4P and I got 1400mA from three NiMH batteries. Does this mean that each emitter saw 350mA or each emitter saw 1400mA?

Thanks!

 

[PCC]

It's amazing what a few quiet minutes all to myself can do for my thought processes.

To answer my own questions: I can probably get away with running one of these small boost drivers but I would end up splitting the output four ways, one to each emitter. That means that a 1A driver will provide each die 250mA. Since there are few drivers out there that can push more than 1A from 3V I'm pretty much stuck with this. I think I'll set these lights up with XP-G R5s instead or wait for the XM-L.

As for the second question, 1400mA split four ways gives me 350mA to each die.

Does this look right?

 

[Justin Case]

Yes, the drive current divides.

The BadBoy Nexgen boost IC is rated to a max of 5.5V output. So you are going to push it at its limits with a 2S2P MC-E driven at 250mA per die.

Probably better to wire the MC-E in 4P and run it with a BBNG1000.

The XP-G is probably easier to deal with since you don't have to wire up a bunch of tiny terminals in 4P. And with an R5 bin, you'll probably get more lumens vs the MC-E, as well as get better throw.

Note that under load, your cells won't deliver 1.5V each. For ~1A-2A draws, big D NiMHs could hold 1.25V-1.3V, giving a total of about 2.5V-2.6V. Fortunately, the XP-G has a low Vf at 1000mA drive, and thus you should be well within the switch current limit of the BBNG's boost IC -- meaning you should reach full regulation for basically the full run time.

Make sure that you power the BBNG only with a load (e.g., an LED connected) applied. The BBNG will instantly fry if powered with an open load.

 

[PCC]

Thanks, JC. I'm actually leaning towards running an XP-G with a BBNexgen 750 for longer run times and about 90 less OTF lumens. Now I need to find a project for the pair of MC-Es that are going to show up in the mail soon.