The emitter is probably seeing 2.8A. Each battery is supplying 1.6A so 3.2A and the driver is probably about 85% efficient so that brings it a little less than 2.8A.
I think that is a reasonable explanation.
The emitter is probably seeing 2.8A. Each battery is supplying 1.6A so 3.2A and the driver is probably about 85% efficient so that brings it a little less than 2.8A.
I think that is a reasonable explanation.
The short answer is no, but you can make an estimate.
Calculate the power used from the batteries, i.e. voltage * current, with two LiIon batteries and 1.6 ampere it is: 2*3.7*1.6 -> 11.84 watt
A led has about 3.6 volts over it, this makes the led current power/voltage: 11.84/3.6 -> 3.29 ampere, but this result is only valid in a ideal world, the driver will have some looses. For a buck driver it might transfer about 90% of the power, i.e. the real current is 3.29*0.9 -> 2.96 ampere.
The above estimates are not very precise:
The battery voltage (As seen by the light) depends on the actual charge condition of the batteries, the current draw and the loss in the ammeter.
The led voltage depends on the led type.
The efficiency of the converter varies with design and type, the best buck converters is above 95% and a boost converter can be below 70%.
gcbryan, HKJ - Thanks to both of you for showing me the math that shows my light is most likely pushing the XML emitter to its limit for a single emitter setup.
I think i got a little disappointed with it when my Sky Ray 3800 arrived with its crazy output.
Agenthex, actually nowadays I rely more on my reflected ceiling/walls for "lumens". This is the bottomline, where the beef is. And of coz "throw lux". Sometimes i bring them out for walks...late at night when there are few people. LOL!
Yes, I'll eventually get around to doing the Everyman-Lightbox which any member can make and test their lights with reasonable consistency. Did some prototyping w/ it, but might have to get some more milk cartons to test if internal reflectivity is consistent.
You always have to measure DC ampere, but if the light is drawing the current in pulses, not all meters can show the correct current.
Another problem is voltage drop over the meter and probes, it can easily change the result by 30% when measuring a few amperes from a single LiIon battery.
I have a guide on how to use a DMM on my website.
Thanks HKJ! In your guide i couldnt find a poignant note why the user MUST NOT use the mA/uA-setting of the DMM when measuring tailcap amperages e.g. in Low-mode or Moonlight-mode. You did mention the burden voltage on BLF and this is the exact reason as i learned (once the concept of shunt resistor, reduced accuracy and burden voltage was explained to me by Dave's webpage and video) but maybe you could include the warning more explicitly in your guide.