EC4S is Apart, Which Resistor to Stack Onto R010? Help the Noob

:???: Maybe I should have titled this thread “Help with resistors! Help with resistors! Help with resistors!

So I have a question about resistors. I have mostly taken my EC4S apart as seen in the pic. I’ve located a single R010 resistor as a prime suspect for a current mod. It is located inside of the two story driver at an angle that just might be negotiable for stacking another resistor. However the only resistors I have are R120. While I believe they would be appropriate for adding a fair amount of current without overdoing it, I certainly don’t have the facts on this.

Thing also is, my R120s are WAY tiny compared with the R010 on which to stack. ok, Can you get different sizes for the R120 resistors? I guess by extension I’m asking all the resistors come in different sizes? I purchased R120s from Mouser and these are the ones they sent me. And that my friends, is the extent of my resistor knowledge. See why I need help? I have already however current modded three different lights with these with good results…. L6, eagle Eye X7, and can’t remember.

Essentially, if you want to skip everything above, I’m asking what is the right resistor to stack onto the EC4S’s R010?

blind leading the blind.

let me see if i can help.

often one can double the factory resistor (sounds right to me but i may be off) so you could look for another 010 resistor.

Also yes they do come in physical sizes i think it is the dimensions in mm 6x3, 8x5 expressed as a code. maybe like 0603 or 0805

I love the nitecore lights and wish i could find how to modify my p36 correctly.

consider that factory lights are designed designed to exploit the sweet spot of runtime, lumens etc etc.

i might be wrong here also, but…

as lumens are like decibels in that you need to double the sound presure to get 3db more sound, it takes a lot more power to make a “noticable” difference in light output.

my point here is that decreasing the resistor value by 10% may not make a noticable difference. while adding the same resistor is not unheard of.

i hope i did not confuse you or your issue.

Not more confused from reading your post. It’s actually exactly the type information I was hoping to receive, at least for the most part. If all the extra numbers in the resistor specification are code for dimensions then I can go back now and make sense enough to know which resistor I’m actually buying.

So although I still don’t have a definitive answer as to what exactly I want to do with my EC4S at this stage, I have a lot more to go on. I’ll probably order a few R010s and use one over the existing R010. However, seeing your mention of bypassing the resistor with solder (never even knew), is quite tempting to try. Without knowing specifically the expected result however, I’m too afraid of ruining the light somehow.

I’ll have to gather a bit more information before moving forward with this mod. Thanks Ronin42, your reply was quite helpful.

I suggest not to bypass with solder. I’ve ruined a couple drivers doing this. Some were fine with it but it’s a lottery not in your favor. However, I am resistor moddedmany lights as well as the XML version of this light. I only added an r100 over the r050 but gave noticeable increase in brightness.

Thanks for the helpful info. I’m thinking this one’s an xhp-50, so maybe double r120 on top of the r010 would work ok. I assume it’s ok to put two resistors on top of the one like that. It’s a bit of a tough angle so I hope I don’t mess the thing up whatever I end up doing.

papaslightsaber, since the sense voltage across those resistors is kept constant and I = V / R, it is clear the additional current through each additional resistor is inversely proportional to its value.

So, a couple R120s stacked over the R010 will ramp up the driving current by 16'6̅6̅6̅% (one-sixth).

Cheers ^:)

Ok thanks Barkuti. So let me then attempt to make sure I’m understanding what you’re saying. Any added resistance is only proportional to any resistance that is already present? So for example, if I had an R005 resistor to begin with then the addition of 2x R120 add only half as much proportional resistance as the R 010 example? 8.333% or 1/12?

However, as far as lumens to additional current goes, the relation is no longer clean correct? Aside from more=more and less=less. 12% more current not necessarily = 12% more lumens. But it should = more, assuming thumbs aren’t included in the eqation. Thank you.

Of course, the impact of any each additional resistance in parallel with the current sense “stack” is proportional to its value. Each additional resistor is, in fact, like an additional current “hose” whose section is proportional to the inverse of its resistance, thereby reducing the overall path flow resistance.

A couple R120s is equal to 60mΩ. Obviously, in order to achieve the same current pathway section increase over a 5mΩ resistor stack, half of that resistance value is required: 10/60 = 5/30.

A borrowed pic:

With regards to your second question, bear in mind that beyond peak efficiency driving current level, which to my knowledge is a pretty low value, the harder you drive a led the lesser the efficiency it displays.

Cheers ^:)

I personally would be afraid of damaging that driver with the extra current. This light is pretty maxxed out for what it is already and if you mod it will the minimal lumen gain be worth the risk? If you manage to bump it up 200 lumens it will not be noticeable but it may be enough extra current and heat to destroy the light.

as far as the resistor details i am no expert.

as far as pushing more current through above the near/at max factory spec:

emitter efficiency drops

and the raw number of lumens increases rapidly needed to make a noticable difference.

for example add 100 lumes to 50 lumens (big difference )
add 100 lumens to 1500 lumens (no difference )

so depending on design requirements there is definitely a point of diminishing returns.