Maglite’s new ML300L caught my eye, but for the wrong reason.
It appears to use an XM-L2, and 625 lumens is certainly no sweat at all for the emitter.
According to Match’s testing here the XM-L2 will be drawing about 1500ma to produce 625 lumens. The Vf will be somewhere around 3.25v.
Unfortunately I do not know the bin of the Maglite LED or what bin Match was testing.
The 16 Hr battery life is what smells fishy. Your average Duracell D Cell does NOT like currents more than 1A. Granted this is a three cell light for a while the battery voltage is higher than the emitter Vf, and the current from the cells will be lower than the emitter current minus any losses in the driver.
At 625 lumens the emitter is drawing 4.875 watts (3.25v*1.5A) to find battery current, you would technically need the voltage under load to be accurate, but lets say that it is 4.5v for the sake of simplicity.
( P/V=I 4.875/4.5=1.083A) 1.083A would be drawn from the cells, disregarding any driver losses.
According to the Duracell datasheet for their copper top D cells, at 1 amp discharge, the voltage drops like a brick. It falls to 1.1v in the first 5 hours. Even if the driver can boost the voltage after the cells fall so low, the current draw would be ridiculous, and the voltage would continue to drop like a stone.
There is absolutely no way that anywhere near 625 lumens is maintained for more than 5 hours from 3 D cells, and this is without including the heat factor!
I do applaud Maglite for using a better LED, but to stay competitive they will need more battery options, and better regulation.
DISCLAIMER: I’m not trying to bash Maglite, I am simply evaluating their claim.
Indeed, the math doesn't lie, it sounds like the 16hrs may be true (and that a boost circuit is used when the batteries get too low), but the 625 lumen drops 'like a brick' as you state.
Probably they are gaming the ANSI system. ANSI run-times are calculated to some small percentage of light output. I think it was 10% or so. The ANSI lumens are measured at 30 seconds after switching on. So, they could have basically what we would call a turbo step-down after 30 seconds to a much lower lumen output level and hold it there for the run-time. Apparently, some manufacturers do this with some regularity, because it fits within the parameters of the ANSI rating system, yet maximizes their supposed “specs” on paper.
Well now, I did just read your link and……………………This is what it says;
Runtime
The amount of continuous runtime (in minutes) until the light output drops to 10% of its original value (measured 30 seconds after turning the light on).
This test is done using the batteries included with the flashlight.[1] If no batteries are included, the test is done using the manufacturer-recommended batteries.[1]
The test is done in an integrating sphere just like the lumen test with light output measured every 15 minutes. 10% of brightness probably gives inflated runtime numbers. In the past, some testers used 50% to be a little more practical, but with most batteries, the drop-off is usually pretty quick and the time between 50% and 10% usually is not long.
So, to sum up; ANSI run times don’t mean squat.
If Maglite wants to be Upfront and Real, they can show us a Lumen graph over the full 16 hours.
Some thing tells me that are not going to do that.
If it only needs to hit 10%, maybe it steps down thru the modes as the voltage drops?
+1 on that. If Maglite wants to re-gain the market dominance they used to have, run times that are inflated by a factor of three wont help their credibility any. I can understand TrustFire or an even more obscure cheapo light not telling the truth with run time, but a $70 light? That is supposedly using cutting-edge technology?
They’re not competing with rechargeable lithium lights but with older mag lights and selling to people who still want to use alkaline cells. Fact is, it’s the cells that suck. People that still use alkaline cell lights expect a light to get dim over time because that’s the way they’ve always worked and ANSI ratings fit that expectation. Very few people know better which is why they go wow over just about any light a BLFer can produce. Bashing Maglite for using a well known rating system and using it accurately is a waste of time. Bashing them for dragging their heels through old technology is fine though. I’m just glad they still sell the older Incan versions that cost $20 and have more aluminum than any $20 Chinese light.
Match’s testing indicates roughly 300ma to the LED to get 130 Lumens, and the LED Vf is only maybe 2.6v at this current. The LED is drawing .78 watts. The battery is seeing 173ma at 4.5v.
At 250ma in Duracell’s datasheet, the voltage falls gradually until the battery voltage falls to .86v, where the boost driver would likely kick in. Duracell only shows down to 0.8v, but if the driver really is boost capable, it would seem that it might make another few hours. At least 50 hours at 130 Lumens is practically guaranteed as far as batteries are concerned.
The current in the datasheet is 77ma higher, therefore the battery voltage might not fall as fast at the actual current. 77 hours could be feasible.
Given the wildly outrageous Chinese lumens claims it’s almost sad that Maglite is so proud of such weak claims even if they are closer to the truth. What bothers me most about alkalines is the propensity for leakage and ruination of a good light. That and knowing that most get tossed instead of recycled. A single alkaline cell holds more energy but a rechargeable cell is capable of holding much more per manufacturing cycle and the shear quantity of alkaline cells sold guarantees a dismaying amount in and out of landfills.
Thankfully manganese dioxide (or manganese IV oxide, as it should be named) is insoluble In water. Zinc chloride is very soluble though. That’s got to mess with rivers sure enough.
Yes they can be gamed, but imagine if no standard about how to measure existed? Now that would be a mess.
If you think you can make a better standard, please feel free to get it agreed to, and actually used. Having worked for a standard organization I can tell you it is no small task, one that often has little or nothing to do with engineering issues.
