How do I check amps while the light is on? I unscrewed the switch/ back and put the neg from DMM on the battery, + on the exposed metal body of the threaded part. Got .67 or so on DMM, nowhere near 2.28 amps board is listed at. Wondered what’s going on?
The DMM leads are too restrictive and giving a false reading. Make sure too that you're in high for that top reading. Simply bump one of those 2 connections like tapping the switch to change modes.
In my experience, the stock leads won't give an accurate reading on Amps. I've replaced mine with 12ga solid wire leads before, then stepped up to Tenergy 12ga multi-strand that are very flexible which makes it much easier.
Oh OK. So I might be getting 2.28 amps with that then?
I’m getting 3 modes like I’m supposed to, I should be in high
Also are the battery charger measurements correct or are the amps off there too?
Usually the DMM reads Voltage more accurately than Amperage. So even if that's off it won't be by much. The amp readings can be off quite a bit, depending on your leads and the meter you're using.
When I first discovered that, I took a piece of Romex house wiring and stripped the insulation from the ends of 2 pieces of that solid 12ga wire. With it about 3" long for each one and bent to allow me to make contact, I got much more true amp readings.
Be careful with the amp readings, you don't want to short circuit one of these high discharge cells, and likewise make sure when you're switching from Amp readings to Voltage measurements that you move the leads to the correct positions on the DMM. These Li-ion cells will burn you if you make that mistake, and much worse CAN happen!
I just built a light that uses one emitter and one cell and pulls 16A!!! That can hurt ya! Cree emitters won't pull that much in single configuration, this is a Luminus SST-90.
Wow! 16A! Where do you get a battery that can handle that?
The amp readings seem right on the charger. 250 ma or so charges 2000 ma AW from a bit under 3.9 V in 5-6 hrs.
But when I tested amps with an 18650 directly ( probably a bad idea) I got 3.5 or so, so there must be some internal resistance, as I think they can deliver more than that
The spring on the driver can rob you of around 600mA, solder a wire inside the spring or use copper braid. That will cut some of the resistance.
The Samsung 20R is a 2000mAh cell that will deliver huge power levels, so far it gives the most of any I've seen. It's rated at 22A continuous. The Sony C4 is rated at 30A and there's an Efest Purple that's new and it's rated at 35A. But the older Samsung still reigns supreme in any testing I've done.
4 of the 20R's in an SupFire M6 will give almost 5000 lumens of output in the lightbox!!! That's a lot of amperage on tap! We figure that light is probably pulling 16-18A, best I can test I've seen over 13A but don't think I'm getting a good ground with the light apart for the testing. :)
Oh yeah, make sure you've got a good solid ground as the light can't pull amperage without it. ;)
How do I tell if I’ve got a good ground? Don’t think I’ve heard about that.
Those are some amazing numbers…… 5000 lumens, 16 amps. And I didn’t realize you could get that amperage out of an 18650. And the 20R’s aren’t that expensive.
The reading is correct, but the leads are usuallt too thin, so the addition of a meter restricts the actual current.
…just saying…
Oh OK I was worried I’d have to get a more expensive meter. Sounds like larger gauge wire is all I need. Thank you for that clarification
Measure resistance from the tip of the spring to the body (only the very top of the spring contacts batt -). That’s why we all do the copper braid mod. The braid can carry way more current than a thin spring.
You mean to the back of the body or to the driver? Just set the meter on Ohm measurement?
I do the spring bypass to keep from melting down my springs. :)
16A is the highest by far I've ever seen from a single cell. Cree emitters won't do it, not as a single. Now, a good triple will get close to that...
The Samsung 20R is an awesome cell. And you're right, it's not all that expensive. But compared to the other big dogs it's a little low on the capacity side, with 2000mAh as compared to 2500 in the other contenders.
When using standard drivers in the 2.8 - 3.04A range, a spring bypass can let you get closer to seeing those actual numbers. When you start modifying the drivers, pushing over 4A and beyond, it starts becoming equally important to have the bypass carry the current so the spring doesn't overheat and sag, causing your connection to be broken in many instances. Once you get up over 5A, a lot of us use the McClicky switch or an Omten. And I've recently learned that even the McClicky will sag and soften the spring, including the internal one that pushes the connections apart when you try to turn it off, at over 10A. As long as you're under 4A though, you really don't need to worry about this sort of thing.
Some of us are just crazy addicts...
OK I picked up a scrap of 12 ga. multi strand wire now I am getting up to 1.88 on the 2.28 A driver. Thank you. A light that read about 1 amp reads 2.7+. Will bigger wire give a higher reading? I tried attaching the wire to an 18650, don’t do that! My 10 A went to 11-13 I don’t think I had it for over a a second!
My Samsungs are 20 B, do those have the ability to deliver high A?
DBC I thought 16 lumens was fine awhile back. Now I’m using 2-3 A. I might as well start lookingat the SST’s…… 
I haven't been at this all that long myself. A couple of years ago a big light that made 1000 lumens was expensive, and that sounded insane. Didn't know then that the 1000 lumens was by the math, not actual output. I paid $165 for a Mag build that was only about 700 lumens. It had a 2.8A driver with a single Cree XM-L emitter. Wow. Now I'm getting pretty close to that from lights that use a 10440 cell (Li-ion version of a AAA)
It's addictive! And options, oh my! When I first got into the flashlights and found all these 3 mode drivers I thought it was just fantastic! I just built a new FET driver for my SST-90 light and gave it 7 modes. :) Yeah, see, there's that. Me? Building drivers from scratch and re-working UI to include extra modes just where I want em then flashing that into the MCU. Wow! A year ago I wouldn't have known what you were talking about if you said MCU. lol
The more you know, the more it costs. Play dumb! ;)
Be careful, trying to measure the amperage of a dead short might void your DMM's warranty. And your bladder. 
Lol good idea DMC! Was thinking about programming microcontrollers myself.
Skin resistance is so high a 4V battery won’t zap you just from touching both ends of a cell
That’s good to know Rufus. I was wondering if you could electrocute yourself with the high current stuff.
Gj yeah. I was over 10 A in no time. I should’ve known when I saw a spark when a bit of the wire connected to the DMM sparked.
DBC I had none of this stuff at the first of the year. Then I picked up a Cree 7W 300 single AA, then another, then 14500’s, which blew a light which I then had to try tofix, then 18650’s……….you know 
Been taking some guys night hiking, pretty good