Kitchen Panda
Enlightened
I'm looking for a new headlamp to replace my aged Fenix HP11. I was all excited to read the numbers on the new model HM65 - 400 lumens for 22 hours! Wow!
Too good to be true. I suspect it's a 400 lumen needle at 30 seconds and then drops down to 10% fairly rapidly. ANSI ratings allow this, but it makes it hard to compare to more "rectangular" runtime profiles.
I realized a 3500 mAH 4.2 volt LiIon has only 14.7 watthours in it. Let's say you can get 100 lumens per watt, so that's in striking distance of 1470 lumen-hours. 1470 divided by 400 lumens is 3 1/2 hours, about what other single 18650 powered headlamps claim.
Looks like this model is so new there have been no runtime tests published yet. I"m very disappointed in Fenix for publishing what is clearly a nonsense number, without any runtime graphs to warn us what the real output vs. time characteristic is.
Looking forward to the first reviews. I think I will postpone my purchase decision till I can read independednt 3rd party runtime graphs - clearly the headlamp makers have taken the "Sears compressor horsepower" approach to rating their products.
Sadly,
Bill
Too good to be true. I suspect it's a 400 lumen needle at 30 seconds and then drops down to 10% fairly rapidly. ANSI ratings allow this, but it makes it hard to compare to more "rectangular" runtime profiles.
I realized a 3500 mAH 4.2 volt LiIon has only 14.7 watthours in it. Let's say you can get 100 lumens per watt, so that's in striking distance of 1470 lumen-hours. 1470 divided by 400 lumens is 3 1/2 hours, about what other single 18650 powered headlamps claim.
Looks like this model is so new there have been no runtime tests published yet. I"m very disappointed in Fenix for publishing what is clearly a nonsense number, without any runtime graphs to warn us what the real output vs. time characteristic is.
Looking forward to the first reviews. I think I will postpone my purchase decision till I can read independednt 3rd party runtime graphs - clearly the headlamp makers have taken the "Sears compressor horsepower" approach to rating their products.
Sadly,
Bill