Modding questions

LED Flashlights – General Info 18650 Flashlights
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Considering building an S2+ triple, maybe a C8 also, as my first foray into building/modding lights. (Previous experience lego-ing P60 pills).

Questions I’ve thought of so far, while browsing mtnelectronics:

When building a triple, emitters wired in parallel seems to be the standard? What scenario would series wiring be used?

In parallel, the amperage draw from the battery is equal to the sum of the amps across each emitter. So three XP-L HI at 3 amps each would need 9A from the battery? (Assuming the rest of the light can support 9A - springs bypassed, etc)

When spec’ing a driver, do you take into account losses in the circuit, and “overdrive” the LEDs assuming some amperage will be lost? For example, if I wanted to drive a triple with 1.5A across each emitter - would I spec a driver for exactly 4.5A - or spec a driver for 5A assuming there will be 10% (or whatever) loss in the system?

How can I predict what amperage from an LED, battery, and FET/DD driver? Are there high-amperage (say, 6+ amps) drivers that aren’t FET/DD designs?

How hot (and how quickly) will an S2+ light get with high amp/outputs? Or alternately, how hard could you run a light if I want it to still be hand-holdable after 3 or 4 minutes on its highest output? What about for a C8 sized light?

Thanks!

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Series LEDs are more often employed when using series batteries or when high current isn’t spec’d such as from 1.5v cells. For single liion cell hosts it’s not a very viable option since there aren’t any boost drivers that can supply as much wattage as direct drive to parallel LEDs. Even buck drivers with multiple cells cannot match direct drive which is simpler and requires fewer components that are less likely to fail. You will need to use a lower mode to keep an S2+ from getting hot, exactly which mode below turbo depends on the LEDs, modes, cell, etc. By their nature most FET drivers are hard to predict precisely what output you will see because LEDs are very voltage sensitive and differences in mV available can cause the current to vary greatly. That’s why so much attention is paid to reducing or eliminating possible sources of resistance that cause voltage drops. The bigger the light the longer it takes to heat up. The most critical component is the copper DTP mcpcb that allows the heat of the led die to more quickly move away from the source. Without it, these fet drivers quickly overheat the LEDs. Beyond that, how hot is too hot?