Driver amp measurement questions

Hi All

Ive used the QLITE driver from Mountain Electronics with 8 extra 7135 chips added to all of them. Thus, I presume the spec on the driver should be 3.04 + 2.8 = 5.8 amps?

I did the following messurements and have the following questions:

1. Convoy S2. Ive used the standard flaslight body and the driver mentioned above. Ive built 2, one with xpg2 dedomed and xml2 dedomed, on copper. When I measure the amps without the flashlight body, thus, only with the pill assembly, using a 35a efest cell, I get 5.3 amps max. Im using a fluke meter to do the measurements, which Ive compared with using...

this...

Both measurements are very close, out with 0.1 amps. Thus I assume my readings are correct.

My first question. Is the reading of 5.3a acceptable, or should it be higher?

Then, if I measure amps at the tailcap, I cant get more than 4.0 amps? This is the case with both S2's.

Why am I loosing so much amps and is this acceptable. My aim with the builds was to get around 5+ amps.

2. Convoy C8. Same setup as in number 1. Here Ive only measured amps at the tailcap, 2.4 amps max! I still need to measure without the flashlight body. This is an enormous drop in amps? Why?

3. Convoy M1. Im using you QLITE-ZNR driver with 8+ 7135 chips with a mtg2 on copper. Running 2 x Efest purple 18350's. Here Ive also only measured amps at the tailcap. 2.2 amps max! Still need to measure without the flashlight body.

Can anybody shed some 'light' on these scenarios?

Thanks

With a setup like this, the smallest little voltage drops add up in a hurry to limit the performance. Especially at those high currents, the LED voltage is pretty close to the battery voltage so you have very little headroom. The 7135s need 0.12V, and at 5A even small resistances add up. At 5A, a piece of 12 AWG wire (what's on your power meter) drops 8mV per foot! The probes on your Fluke meter probably are no heavier than 18 AWG, which drops 32mV per foot. The meters also have a sense resistor that adds some more. Some part of the body must also add enough to matter.

My guess is you're just running out of voltage. You'd probably notice a difference in brightness between measuring tailcap current and just putting the light together. Taking the meter out of the circuit would improve things considerably.