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Buck driver question

Nute

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Hello, I am currently running a a140 diode on a 1.25a fixed current driver, using 2 3.7v 16340's. My question is, would running 3 3.7v 16340's instead of 2 cause any issues? Would the driver produce more heat, mA output, or possibly damage the driver? The reason I ask is the host I am in the process of swapping over requires 3 16340's.
Thanks,
Nute
 

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NO DON'T DO THAT! You will fry the driver and probably the diode too. Look up the specs for the driver, they all have a min-max input voltage. Yours should require 2 batteries for that diode. 3 and its fried. If your using a host that takes 3 then you need a spacer to fill in for one battery.

Alan
 

Lifetime17

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Hi to bad it's not the M140 diode then you can run it at1.8a with 2-18650's . Your 1.25a driver might over heat and the a140's are different than the M140 . Search the forum I'm sure there's alot of info on that.

That's alot of Volt from three 16340's it will run but not for long life of the diode. If you don't know plat it safe. There is a diode heaven lol!!
 
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Nute

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Thank you so much! I appreciate that! I'm glad I asked before I assembled it.
 

Lifetime17

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Nite I built a C6 for two 18650's with a M140 the newer diode. And get around 2.2 Wats . That little build burns like crazy.

Correction :: Nute
Anyway check out Mcrouse for hosts this guy is awesome and builds them on the 18650 platform and the price is right affordable. I'm sure you'll like what he has,,
 
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Nute

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I just received a call from the manufacturer of the driver and got some conflicting news. However, I am going to stay in the x2 16340 configuration to be safe.



Yes, you should be able to run the driver with 3 x 16340s without damage and the output current shouldn't change within the voltage tolerance of the driver (which is 3-18V).
 

Lifetime17

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Well that sounds great Nute . The driver passes now how about the diode max voltage input. Check with DTR :: Jordan Ramey send him an email . Another M 140 just got here today for me I run it at1.8A with two 18650's with a G2 divergence is nice burns at long distance to gives me 2.2 to 2.4 w
 
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crazyspaz

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Hi to bad it's not the M140 diode then you can run it at1.8a with 2-18650's . Your 1.25a driver might over heat and the a140's are different than the M140 . Search the forum I'm sure there's alot of info on that.

That's alot of Volt from three 16340's it will run but not for long life of the diode. If you don't know plat it safe. There is a diode heaven lol!!
Nite I built a C6 for two 18650's with a M140 the newer diode. And get around 2.2 Wats . That little build burns like crazy.

Correction :: Nute
Anyway check out Mcrouse for hosts this guy is awesome and builds them on the 18650 platform and the price is right affordable. I'm sure you'll like what he has,,
Well that sounds great Nute . The driver passes now how about the diode max voltage input. Check with DTR :: Jordan Ramey send him an email . Another M 140 just got here today for me I run it at1.8A with two 18650's with a G2 divergence is nice burns at long distance to gives me 2.2 to 2.4 w
What do any of these posts have to do with the question Nute asked in the OP?
 

rhd

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What do any of these posts have to do with the question Nute asked in the OP?
Nute -

Ignore everything everyone in this thread (except crazyspaz) has said. That includes the manufacturer. Assuming you're talking about the Survival Laser in your signature, I don't think they really make their own driver and I'm not sure they actually understand how their driver works.

I think I do - it's a 300-500 khz switch with a relatively low value inductor, small caps, but an IC that on the datasheet can handle a bit over 20V of input. Hence their comment that up to 18V is fine.

It's not.

At three cells of input, the driver will still work, will have the same output current, and it won't burn out or catch on fire. But with the relatively low frequency of their IC, the anemic inductor, and the relatively small caps, you're going to end up with bad voltage ripple.

If my math is correct, you'll probably triple the ripple, by going to 3 cells instead of 2. It will still work, and your diode will still see the same average current, but it will take a much bigger beating in the process. Again, SL probably doesn't know this, and they've probably tested with three cells and saw that the diode worked, so they think it's fine - but it's not.
 

Nute

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Thanks brother, I really appreciate the way you broke that down for me. I kind of figured that it was rated for higher, but will not push my luck. I have a vague memory of a thread that said something about the change of frequencies when adding more voltage, resulting in a hum or decreased diode life. I hate asking these kind of unorthodox questions, but I was unable to find the info I needed searching the bottom search bar. Again, thanks guys for taking the time out to educate me!
-Nute
 




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