Driving the P7

Since the P7 is the newest hot item at the moment, particularly for modders, I wanted to make a thread discussing driver options and developments for this beast.

Here are the current options that I know of that have been done:

++ A simple option is to direct drive off of 3 NiMh's or 1 LiIon/Emoli/A123, possibly adding a resistor, like the one that Mac did here (Emoli), and StefanFS here (3x D Nimhs).

++ KaiDomain's 8xAMC7135 - Linear 'buck' driver, best to use with 1 LiIon or 4 Nimh's. More info on these here.

++ Tri Flupic - Wire the leads in parallel. Provides multi-mode functionality.

++ A regulated option is to use two drivers in parallel such as this set up by Icarus utilizing 2xDB1500 here (buck converters). To get info on DB/SOB 1500 look here. You could do the same with GDxxx converters which are buck/boost converters. Both are available from Sandwich Shoppe.




My current build will be 2 of the 1400mAh AMC7135's (same as the KD above, just mounted separately). This was done by NetKidz here. The problem with linear boards is that they aren't efficient (*edit- depending on voltage), they simply bleed off extra power as heat. But it's cheap and I think it's better than direct driving with a resistor.


My hopes are that someone (*cough, Wayne) would make a driver specifically for the P7 with a trim pot.


Please point out any corrections needed to the above info.

I think that Multi-level driver for SSC P7 under $8 is another good option.

Today I bought 2 Mags 2D Lime Green color for my first mods. One with SSC P4 and one with SSC P7. I am just figuring out how will I drive LEDS. I am thinking about direct driving SSC P7 and 16-mode driver for SSC P4.

If you are direct driving, please let us know which batteries you go with.

Here's one made by StefanFS using 3 D NiMh's:
http://candlepowerforums.com/vb/showthread.php?t=192740

Supernam said:

The problem with linear boards is that they aren't efficient, they simply bleed off extra power as heat.

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I'm getting tired of saying it: Rubbish. They may not be, like any driver used outside its sweet spot, but if your average input voltage isn't hugely greater than your LED operating voltage, linear regulators can be very efficient, even better than most buck and/or boost regulators.

TorchBoy said:

I'm getting tired of saying it: Rubbish. They may not be, like any driver used outside its sweet spot, but if your average input voltage isn't hugely greater than your LED operating voltage, linear regulators can be very efficient, even better than most buck and/or boost regulators.

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Read carefully. That's exactly what I am saying. They bleed off EXTRA power as heat. Clearly if the "input voltage isn't hugely greater than your LED operating voltage", then it wouldn't be considered EXTRA. The linear driver isn't really doing anything when the input voltage is the same as or less than the output voltage so of course it's going to be more efficient AS IT APPROACHES THAT POINT. But that's not the reason why we use them. We use them to bleed off extra power as heat. When it is doing so, it is NOT efficient. The less it has to work, the less heat is being dissipated, the more efficient it is, and conversely, the more it has to work, the more heat it is giving off, the less efficient it is. In a way, we can say it is efficient at doing nothing (litterally)!

I choose to use these drivers simply because 1) they are cheap, 2) they are more efficient than using a resistor, and 3) they keep the LED from being overdriven BECAUSE THEY BLEED OFF EXTRA POWER AS HEAT.

With respect Supernam, you seem to know what you're talking about but you appear to have been a tad careless in your wording in a couple of spots.

Supernam said:

Clearly if the "input voltage isn't hugely greater than your LED operating voltage", then it wouldn't be considered EXTRA.

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If the input voltage is greater than the LED voltage by any amount it's extra. It doesn't have to be hugely greater.

Supernam said:

We use them to bleed off extra power as heat. When it is doing so, it is NOT efficient.

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Did you know that you are saying that dissipating any excess volts as heat is by definition not efficient? You know that's not so.

Supernam said:

I choose to use these drivers simply because 1) they are cheap, 2) they are more efficient than using a resistor, and 3) they keep the LED from being overdriven BECAUSE THEY BLEED OFF EXTRA POWER AS HEAT.

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I was simply curious about this one. Are they more efficient than using a resistor? A linear regulator operates as basically a glorified resistor anyway, and they both bleed off extra power as heat. I ran some quick figures and they came out just 2% different - close enough to make me think that a more accurate analysis might be called for. They certainly provide a much more even output, no question there, so on my own list I'd probably say they provide a better regulated output than a resistor.

Have you seen the AMC7135 testing by Drewfus2101? He shows that with the right choice of battery you'll be over 90% the whole way. Not efficient? :shakehead I say again: Rubbish.

Edit: Yes, of course you've seen that thread - your post is the second to last.

Two more options for you. led-tech in Germany have a new driver specificaly for the P7 here no idea if it's any good. If you wanted to driver more than one I think you could use a CCHIPO for 2 and it would make good sence for 3 or 4. Personaly I want some more optics options before I start playing...

Ifor

TorchBoy said:

I was simply curious about this one. Are they more efficient than using a resistor? A linear regulator operates as basically a glorified resistor anyway, and they both bleed off extra power as heat. I ran some quick figures and they came out just 2% different - close enough to make me think that a more accurate analysis might be called for. They certainly provide a much more even output, no question there, so on my own list I'd probably say they provide a better regulated output than a resistor.

Click to expand...

I admit, after rereading, my wording was not careful. The way I conceptualize these regulators is that they act as a resistor up until the point that the Vin and Vout are close. I honestly don't know too much about resistors, but I believe that DD with resistors would burn off power throughout the whole battery life. I cannot support this assumption. However, when it comes down to it, I think we can agree that linear regulators are better than using resistors. Not to mention you get a flat output as you mentioned above. The way I look at it, you can't go wrong for a couple of bucks each. I'm hoping for a GD2800 or similar from the sandwich shoppe.

IcantC said:

If you are direct driving, please let us know which batteries you go with.

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I had one (vf=I) running direct drive off 3x C4500 NiMH. Current was 3a fresh off the charger then quickly dropped down to 2.8-2.7A.

darkzero said:

I had one (vf=I) running direct drive off 3x C4500 NiMH. Current was 3a fresh off the charger then quickly dropped down to 2.8-2.7A.

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Roughly what kind of runtime with a 3C NiMH set up like that ? ~1.5 hrs ?

Sounds about right. 4.5A/h / 2.8A = 1.6h (theoretically).

Supernam, remember to include the www. in your links. (It was an official recommendation a few months back after we had the big upgrade.)

Thanks for the heads up! I was simply copying and pasting from my address bar and didn't notice.

And I just found one in my list that didn't have it.

Thanks for your reply Supernam, I got a question, I was about to order 2 SOB at 1.5a at the sandwich shoppe, but can't seem to get the resistor values right.

Is it .05 R1 and 0.1 R2 = 1.5Amps?
or is it .05 R1 and .05 R2= 1.5 Amps?

Thanks!
AlexGT

I believe it's .05 and .10, can someone confirm this?

Supernam said:

I believe it's .05 and .10, can someone confirm this?

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Yes that is correct. Now that there are .05 resistors available at the shop, .05 & .10 will get you a parallel resistance of .033333 which will get you 1.5A. Before the .05 resistors were available, using 3x .10 resistors will get you 1.5A.

2x .05 would get you .02 parallel resistance which equals to 2.5A, doubt the SOBs could handle that.

ifor powell said:

Two more options for you. led-tech in Germany have a new driver specificaly for the P7 here no idea if it's any good. If you wanted to driver more than one I think you could use a CCHIPO for 2 and it would make good sence for 3 or 4. Personaly I want some more optics options before I start playing...

Ifor

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They say this: Max. input voltage: 2,0V over LED voltage

Makes for limited battery choices, imho.

hi guy's
any idea of the driver used here ?
http://www.qualitychinagoods.com/lumens-4xssc-bulbsfbp7-p-980.html
many thanks