does bb700 get hot under the collar?

[across the pond]

Does anyone know if a bb700 converter board (just the board driving a remote led) requires its own heatsinking? Cheers. /ubbthreads/images/graemlins/smile.gif

 

[flash....]

Why yes, yes it will.
Even more so as the batterys deplete.
The regulator pulls more current than it gives.
The delta is energy spent and generates heat as all current regulators are not 100% efficient.

 

[dw_1984]

So flash, you're saying that the actual BB converter board has to be heatsinked in addition to the LED?

I haven't bought the BB700 yet but could you show me where I would put a heaksink on the convertor board. I'm a little confused on that part.

 

[FalconFX]

I would just make sure the board has some way of contact with the side, metal body of the flashlight. I'd just apply a dab of Arctic Silver onto the sides as it contacts the aluminum walls, and it should do the trick...

In a nutshell, think of it like a BB400/500 dropin for an MM and how it dissipates heat...

 

[tvodrd]

across the pond,

You might consider cutting/filing some aluminum pieces to thermal-epoxy to the IC and diode. On the 2 750s I have, Wayne didn't have the ICs down against the ground plane(?) real well- there's compound in there, but it's too thick to do as good a job as it might. (Don't shoot, Wayne, I still love 'em! /ubbthreads/images/graemlins/grin.gif)

Larry

 

[flash....]

dw_1984...
Yes, the BB700's & 750's require special treatment vs. the 400's & 500's (which should also get some kind of heat sink as well.)
tvodrd said it best with: [ QUOTE ]
You might consider cutting/filing some aluminum pieces to thermal-epoxy to the IC and diode.

[/ QUOTE ]
That would also be my reccomendation.

 

[dw_1984]

Ah. That helps a lot. Thanks!

 

[dat2zip]

The Badboy converter boards especially the higher current outputs will run fine in free air. Although, that too is not recommended.

The IC thermal to air is aweful. It's not good at all. Altering this every so slighty makes a huge impact since it is terrible to begin with. As such, using your finger on the IC would be more than sufficient to keep the IC happy.

The thermal paste (Arctic Alumina) does more than an ample job to keep the IC happy. The problem here is at 85% efficiency and driving a 5W means the board is dissipating nearly a Watt of power.

So, what am I babbling about... What I think I'm saying is the IC with goop is OK. But, the converter board needs to move some of the 1W of heat away from the board. That really means some thermal path is needed besides air. Any epoxy, goop, RTV is sufficient to pull some heat away from the board to keep it happy.

I hope this helps.

Wayne

 

[ElektroLumens]

I hooked up a BB750 to 3 'D' cells in a Blaster II, and mounted a 5 watt LS. I had thermal shutdown. The board needs to somehow be sinked. I never followed through with a few ideas I have to sink the heat. I made the mistake of putting it in the switch holder, and covering it with electrical tape. This is a bad idea. Somehow the board, or, the chip, needs to be sinked to the aluminum body. The circuit is a great circuit, but the way I used it was lousy. Good consideraton should be taken to cool the board. IMHO.

Wayne Johnson

 

[Christoph]

Wayne
So the bb700 driving a 1 watter and my bb750 driving a five watter that I've built into drop in replaceable modules that are potted in rtv should do a fair job sinking the heat to the nexstar AA bodies they are in. I've measured temps on the one watter of 48 C with no more than a one or two degree differential between the sink itself and the bulk of the body.These temps were arrived at within the first 15 to 20 minutes of operation. The five watter I have not run for more than 5 to 10 minutes at a time because of the expensive cr-v3 batteries but it seemes to get a good deal hotter quicker. These two nexstars start gettin warm within the first minute or two of opperation so my pills must have a somewhat efficient heat path, they are held in place with internal circle clips surrounded with artic silver grease the fit is snug about .008 in.clearance to the body.
Chris /ubbthreads/images/graemlins/grin.gif Wayne thanks for the converters. looking forward to your next generation converters./ubbthreads/images/graemlins/thumbsup.gif

 

[dw_1984]

I have a 20mm washer from Home Depot and it has an inner diamter of 1.1mm. The inside opening is large enough that all the metal connectors on the bottom of the BB700 are visible. Would this make a good heatsink for the board if the BB700 was mounted on top of it with some AS? Or should I go for a larger washer that actually touches the walls of the Mag-lite?

I'll try and post some pictures when I find my camerea.

-Daniel

 

[Bullzeyebill]

The MM+ is pulling about 1 Amp from the batteries. How come there is no thermal shutdown? To led is still getting high amperage. Bill

 

[tvodrd]

I filed an aluminum washer to rest against the IC and diode on a BB750, and come to the same height as the inductor for my "KL4." I potted the thing with Arctic Alumina epoxy, and potted the ***'y in the copper slug of my "KL4," with an E2 body. Unless I am holding it, the sucker starts flashing at about 5 minutes! When I get around to it, I hope to publish the ultimate heatsink for a BadBoy.

Larry

 

[dw_1984]

Can anyone tell me what part on the BB is the diode? I'm assuming it's the large green coloured thing? As you can tell I'm a complete newbie.

My plan is to heatsink the bottom onto a washer and connect it to the body. Should I do something with the diode? And I know this has probably been discussed but RTV means room temperature vulcanizing but is this a property of an epoxy in that it solidifies atroom temp?

Thanks.
-Daniel

 

[dat2zip]

tvodrd,

What battery voltage are you using? If it's around 4V, expect bad things from Badboy 750 as it'll be sucking nearly 2A from the batteries. Hey, there's no magic bullet.

dw_1984,

There sound be a little rectangular black thing near the IC off to one side. That would be the diode. The two black things are the ones that need the heat sink.

Hmm, As I can recall, as long as I pressed my finger on the IC everything was fine... Seriously, driving the 5W LED is pushing the IC to it's limits in many ways.

Why doesn't the Madmax @ 1A get hot? For one, the Madmax has a more efficient switch element inside the IC and 1A is is not near the 2A the Badboy can switch.

Wayne

 

[dw_1984]

Thanks Wayne!

I've been thinking about potting the converter. I just need to know how to do it and what to use. Can anybody help?

Thanks,
Daniel