need boost for 2d mag

i want to run a p4 off a 2d mag. what circuit do you guys recommend. im thinking about an amp, if i can get a high and low thats great, but i'll take a single mode light over 5 modes any day of the week. obviously gonna need a boost circuit. what has proven reliable and efficent. i'm looking at $10 tops if possible.

How about just converting to 3C and direct drive?

wildstar87 said:

How about just converting to 3C and direct drive?

Click to expand...

Or 2p 18650 (similar capacity, but lighter), but either way you suffer about a 25% capacity hit -- so if your driver's better than 75% efficient, you will get longer runtime on the boost driver.

If you are interested in a 2 parallel 18650 in a 2D maglite i sell an adapter

https://www.candlepowerforums.com/threads/226320

Badboy Next Gen 1000mA Step Up Converter

http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=730

wildstar87 said:

How about just converting to 3C and direct drive?

Click to expand...

i already have built a few direct drive lights. i have a few more planned too. i need to fill a couple 2d bodies, and a couple 4d bodies, but we'll work on the later together or i'll just slap a 7135 circuit in that one. easier to go down in voltage than it is to go up.

as of last night, i was thinking of dx skew 4735 or 4382. i'll check out that bad boy and post back tonight. thanks for the advise.

no 18650 on this one. not a terrible thought though. i want one or two "in stock" as an option for friends to purchase (for the cost of the build). i've had so many friends see a light and finally say, "i need a good light like that"

i like the efficency of that badboy. can you tell me whats the difference between all the ones listed there. did they mention the output was variable? how does that work?

I am working on two 2Ds at the moment, one with 5 R2s, 8 AA and a MaxFlex, the other I wanted to try and do without making any alterations to the Mag and still be able to use 2Ds (NiMH or primary).

With the BadBoy, would this drive the Crees in 2S2P, or would I need 2 one for each pair in parallel?

jasonsmaglites said:

i like the efficency of that badboy. can you tell me whats the difference between all the ones listed there. did they mention the output was variable? how does that work?

Click to expand...

There are 5 different BB Next Gen configurations and this one is for the 1000mA version:

http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=730

It's a single mode driver.

thanks, now for my 4d mag, which resistor do you guys like to drive a p7?

http://theledguy.chainreactionweb.com/index.php?cPath=48_49_62_31

jasonsmaglites said:

thanks, now for my 4d mag, which resistor do you guys like to drive a p7?

http://theledguy.chainreactionweb.com/index.php?cPath=48_49_62_31

Click to expand...

Depends on your chemistry. For Alkaline only, I'd just DD it; for an alkaline/NiMH light, though, you have to design around the NiMH, as they'll slaughter a P7 in DD, and when you load alkalines, you'll just have to live with it being dimmer.

But really, I wouldn't advise a resistor at all for a 4D P7 -- if you're after full current, use a 2.8A amc7135 board (or 2 1.4A boards in parallel) for the same efficiency and brightness as the resistor on fresh cells, and better efficiency and constant brightness the rest of the way down.

jasonsmaglites said:

thanks, now for my 4d mag, which resistor do you guys like to drive a p7?

http://theledguy.chainreactionweb.com/index.php?cPath=48_49_62_31

Click to expand...

P7 in a 4D would need a buck driver:

http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=1244

https://www.candlepowerforums.com/threads/201981

http://www.taskled.com/hipcc.html


or if you want to go cheap:

http://www.kaidomain.com/ProductDetails.aspx?ProductId=1770

cool. i got 6 more builds on the table. i am debating direct driving one of my builds off 2 d batteries. i thought it couldnt be done through advice given me before but i saw a graph bigwaffles did on running 2d alkalines on a malkoff 4-6d dropin. i dont know if that had any boost build in but it was basicly low brightness for a really long time. i was thinking what a great emergency light that would make.

If the extra cost doesn't dissuade you, you may consider using a P7 or MC-E in 4P instead of the P4, while still driving the LED with the BBNG1000. With that level of drive current, the P7 or MC-E will be underdriven by a lot (only 250ma drive current per die). But you should get a significantly lower Vf vs. the P4 at 1000ma drive current. That should ease the current draw from your 2D batteries, make it easier to run in regulation, extend your run time, and get more lumens than from the P4.

ok, i was considering using a p7 for its efficiency, since this is suppose to be a long runtime, high efficiency project. but i was going for dd, as opposed to BBNG1000. is that not going to work? im getting conflicting information. i think im gonna wire one and see what happens. worst case scenerio i can always move the heatsink to a 3d mag and have a proper build. i just like the efficency and reliability of direct drive.

I'm confused. I thought your thread was what boost driver for a P4 in a 2D Mag.

In a 2D Mag, you have ~2.4V on the input to the driver board. To drive a P4 to the max, your driver board needs to deliver 1A drive current. Vf is about 3.5V at that drive current, so your board has to deliver ~3.5W of power to the P4.

If your board is 90% efficient, then your 2D batteries need to deliver

Iin = 3.5W/(0.9*2.4V) ~ 1.6A, which is well within the capabilities of D NiMH cells.

However, there is some question as to whether or not the BBNG1000 will run in full regulation or in safe mode. The TI docs for the TPS61030 IC regulator used in the BBNG state that the boost current switch limit is set to 40% of the nominal during "softstart", or about 1.6A. After charging the output capacitor to the input voltage, the regulator starts switching. Until the output voltage is reached, the boost switch current remains limited to the 40% level. When the output voltage is reached, the regulator takes control and the switch current limit is set back to 100%.

If you go with a DxxxI-bin P7, then your Vf is closer to 3.25V. If you use an MC-E, Vf could be about 3.1V. That reduces Iin to about 1.5A and 1.4A, respectively. And if your D NiMH can hold higher than 1.2V each under load, you'll be even better off.

If you want to DD a P7, you'll need a battery source that can deliver ~3A at ~Vf or slightly higher. That most likely means 3xD-NiMH. If you don't want to use a dropping resistor, then you'd probably be safest using a J voltage bin P7, to avoid the issue of getting 'lucky" with an I voltage bin P7 and ending up with Vf at the low end near 3.25V.

I've made a p7 M*G 3D using Nimh batteries. It works great and I may change it over to a regulated flashlight if I find a cheap regulated board.
I also want to build a 2D version for my neighbor who is the unofficial protector of our area. He looks after everyone and has a stock 2D light. I want to surprise him with a high output light.

Has anyone used the board that Shiningbeam has on his site? It looks like it would handle 2.5 amps but haven't seen any proof of it.

http://www.shiningbeam.com/servlet/the-132/3-dsh-Mode-Regulated-Circuit-Board/Detail

If it looks like a good regulator I am going to buy a couple and try them out.

It looks basically like a two-board sandwich, each with 4xAMC7135.

jasonsmaglites said:

cool. i got 6 more builds on the table. i am debating direct driving one of my builds off 2 d batteries. i thought it couldnt be done through advice given me before but i saw a graph bigwaffles did on running 2d alkalines on a malkoff 4-6d dropin. i dont know if that had any boost build in but it was basicly low brightness for a really long time. i was thinking what a great emergency light that would make.

Click to expand...

Maybe I misread that thread of bigwaffles's, but my understanding is that he ran tests on two different Malkoff Mag drop-ins -- the one for a 4-6D Mag and one for a 2-3 D Mag.

The 2D alkaline test was done using the Malkoff 2-3 D Mag drop-in, which uses a boost driver.

I don't see a 2D Mag in direct drive working very well for a P4 or P7. If you look at the P4 and P7 docs, the If vs Vf curve goes to a very low forward current at Vf~ 2.5V. The graph essentially shows zero forward current. I calculate maybe about 75ma, giving about 20 lumens for a U2xxxH-bin P4. For a DxxxI-bin P7, I calculate about 5ma drive current at a Vf of 2.5V, giving about 10 lumens out. What's the point of that?

This post contains actual measured data for a DSW0J P7, U2SW0H P4, and U2SV0H P4. For both P4s, if you deliver 2.5V to the LED via direct drive, I'd say the LED isn't going to light up or at best you'll get a moonglow. For the P7, maybe you'll get something but it isn't going to be much.

A BBNG1000 will work very nicely with either a P4 or P7 in a 2D Mag. With the P7, the LED will be underdriven by a lot. You'll get a very low Vf, very little heat generation, yet still get perhaps close to 300 lumens out. The P4 will also be very cool-running and give you around 200 lumens.

dspencer said:

I've made a p7 M*G 3D using Nimh batteries. It works great and I may change it over to a regulated flashlight if I find a cheap regulated board.
I also want to build a 2D version for my neighbor who is the unofficial protector of our area. He looks after everyone and has a stock 2D light. I want to surprise him with a high output light.

Has anyone used the board that Shiningbeam has on his site? It looks like it would handle 2.5 amps but haven't seen any proof of it.

http://www.shiningbeam.com/servlet/the-132/3-dsh-Mode-Regulated-Circuit-Board/Detail

If it looks like a good regulator I am going to buy a couple and try them out.

Click to expand...

Justin Case said:

It looks basically like a two-board sandwich, each with 4xAMC7135.

Click to expand...

The Shining beam driver is one that is often found on many of the Chinese made 1x18650 P7/MC-E flashlights. It's a single board with 8 L7135 chips on it with a controller chip. Running on a single 18650, Shining Beam says it reaches 2500mA. I would venture to guess that in a 3 NiMH C or D setup, it could hit 2800mA as each 7135 chip is suppose to handle 350mA. AMC7135 chips are specified to run on as much as 6V of input, but I've been told you can go up to 8.4V-9V with them. The thing is that you really need to find a way to heatsink the driver if you go beyond 4.8V of input. This driver should work great in a 3D or 4D P7 Mag.