Driver help needed for 2C mag TWOJ Mod

I was asked by a friends mom to make her a 2C mag mod.

A 2C or 3C mag is the largest she can handle comfortably.

I was first, thinking of 2 C cells and a Fatman driver, with TWOJ emitter.

But, the fatman wants a 2.7Vin Minimum, and thats about 1.35V each cell.
They might drop below that under load. She also wants to eventually get rechargable C cells.

Would 3 C cells be too much with a fatman?
I know the fatman can handle that, it will go into direct drive, but, would 3 Nimh c cells blow the TWOJ ?

I would use an nflex, but she like the potimeter (knob) on the side for adjustment, better than the button interface of the nflex.

Plus, the nflex wouldnt have alot of Vin to work with, not much to buck.

What do you guys think?
I need 2 or 3C size, dimmable, and use easy to get batteries.

~John

How about the VIP driver? The tech info on taskled doesn't specify a minimum Vin for that.

Hey John, the VIP driver will work on two 1.5 or nimh cells and is dimmable with an external pot like Fatman. I'll email you tomorrow on how to set it up.

george

Yes John, the VIP driver is what you need.
I've build some Mag2C's using VIP drivers.
Runs great one two alkalines or two NiMH batteries.

Yeah, the VIP driver is great. I'm in the process of doing that exact same mod now. And since it doesn't need any heatsinking, you don't need to pot it. I don't like my drivers bouncing around in there, so I cut the bulb post down a bit and superglued the VIP to it. No more bouncing! /ubbthreads/images/graemlins/grin.gif
I wish George made more VIP drivers... /ubbthreads/images/graemlins/icon23.gif
GOOD LUCK!

[ QUOTE ]
Kryosphinx said:
I wish George made more VIP drivers... /ubbthreads/images/graemlins/icon23.gif
GOOD LUCK!

[/ QUOTE ]

I still have some left. And I can build about 30 more (blank PCBs) and then they are all gone. There's not been enough demand to do a new run of VIP PCB's.

I actually have a proto PCB I did quite a while ago that is a VIP driver with a tiny trimpot (like Fatman) that would allow the user to adjust the driver to whatever output they needed. The trimpot could also be used in conjunction with an external Pot to adjust the full output level (like Fatman). This was one of the proto drivers for the VIP light before we decided to stick with a 3 way switch rather than a Pot. If there was enough demand then I could run a batch of those PCB's...

george.

Thanks alot guys, !

email recieved George, ill read over it alittle later and get back to you.

Seems this will do what I need it to /ubbthreads/images/graemlins/smile.gif

I am not real firmilar with C cells.

Anyone have a rough Idea of runtime on alks and Nimhs ?
Running the led at about an amp. ?

thanks
~John

John,

Using a TWOK and 2x Memorex C size 4000mAh NiMh batteries runtime was:

VIP750 => 2hours 33minutes
VIP1000 => 1hour 20minutes.

/ubbthreads/images/graemlins/happy23.gif

Ticy,

I don't recall the efficiency specs of the VIP driver but a very conservative SWAG it should run a hour or so on the alkies and a very long time on some of the newer 4000 and 4500mAh NiMH cells.

I looking foward to your runtime plot /ubbthreads/images/graemlins/grinser2.gif

Later
Kelly

Edit

I see Thomas Distributing has the new 5000mAh MAHA's but they are a little pricy at $22.97 a pair.

glad somebody asked about this.. funny i've used fatman and vip drivers for my mods.. but i'm almost always using rechargeable LiON cells so the VIP is not suitable.. but two NiMH cells works great... two NiMH in a 2c would make a great mod.. run it at 1A and you'll have a killer light.. with the capability of using Alkalines in a pinch.

-awr

From what George has told me, it may not be a good idea to try 1000mA with alks.

Heres what George said...

"If the alkalines can't run 1A - their voltage will drop rapidly and you might get the classic flash-flash-flash effect when a boost converter pulls a battery so low that it goes out of regulation, the battery then recovers, the converter fires up & the cycle repeats."

go look at energizer's site to see what C's can handle.. it's always best to use rechargeables when operating high-power devices anyhow.. why waste money?

look into sub-c sized.. or look into using (2) 18650s ore 18500s.. they will push a lot of power.

-awr

awr,

For MY lights, I use 18650, Pila, and other nimhs.

But this is for someone else, and she wants to be able to use batts right out of a store if need be.
I told her its best to get some nimh C cells for it later though.

oh yeah that's right.. i remember that requirement now..

looking at the energizer data sheet it looks like you can get about 1 1/2W for about an hour per cell.. if you used the VIP driver and de-tuned just a bit to keep the draw below 1 1/2W per cell i think you'd have a mighty fine solution that would work with both alkaline and NiMH.. I am not sure what the minimum voltage is for the VIP driver.. when using 123s i set my vip drivers to 600mA and they work pretty well.. i've tried to use 700 or 800 and they get blinky really fast.. if you put a tiny trimpot in vs a resistor to set the current, you can try say 800mA and see how you like it.. 830 is my favorite setting for a lux 3 because it works out to about exactly 3.0W

-awr

i just re-read the initial post.. and you mentioned possibly using 3cells.. 3C and a fatman might be a better solution.. if you don't care to have 'dimming' that combination should not be a problem.. you probably can't dial it down much lower than 600-700mA with a 'J' bin emitter.. a problem i've had with 1 LiON solutions with 1 lux3 J bin.. i keep forgetting about the direct-drive aspect when Vbat is as high at Vf.. there is a little headroom because of the series diode, so you can probably get away with 3 series alkalines even though they are 'supposed to' be 4.5V.. i doubt highly they'd be that under load.. you could run 1A from 3 series batts.. and especially using NiMH they would just laugh at you asking for 1W each.. an AA NiMH can do a watt.

-awr