IMR's and their effect on amps?

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rdrfronty
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IMR's and their effect on amps?

Ok guys I need an education. I thought I had this basically down, but apparently not after some testing last nite.
To start off with I’ll talk about 18650 lights. I always had the impression that on lights than were allowed to run on them, meaning 4.2V, and their need for power, meaning single XML etc., that any decent 18650 would deliver the same amps and therefore the same lumens. Regardless of it being a IMR or just a good regulated cell. A cheapy ultrafire, sure I’ve seen them put out lower power.
Now I know on many smaller lights with are designed to run for example on a single CR123, that if you put a 16340 in it, it would increase the amps and output. And an IMR does even better on certain high power little lights like my D25C clicky. But I always thought that the bump form 3v to 4.2v made them go into direct drive, or at a minimum the extra volts itself simply increased the output.
But on some 18650 lights I tested last night this believe got all screwed up. Played with a new AW IMR 18650 my brother just got in. Tried it on about 5 lights. HD2010, C8 with T6, C8 with U2, L2 Solarforce with E1320 drop in, and A60. All lights but the L2 has markedly better tailcap amps with the IMR. Both batteries were a little weak so these numbers are not 100% peak, but it gives you the idea. The standard 18650 was a good Eagletac. Both C8’s started in the 3.0 amp with the ET, but both went up to about 4.1 amp with the IMR. The A60 started at about 1.9amp with the ET, but went to about 2.4amp with the IMR. The HD2010. Went from low 3’s to an uber high of 5.4amps. The L2 started at about 3.46 amp with ET and did about 3.6 amp with the IMR.
So what gives?? I though if a battery delivered all a LED needed it was good to go. I’ve tested the batteries before in some lights that were drawing about 5.5amps before out of it and about 1500L otf.
Does the IMR somehow put these lights into direct drive even though the voltage doesn’t change? I assume that’s what it’s doing. And the L2 is a very good regulated driver, so it doesn’t allow the direct drive? Is that what’s going on.
I guess I started this hobby with most high end regulated lights so I never even looked into direct drive and IMR’s. But have discovered the wonderful world of budget lights this last 6 months. It looks like the 18650 world different rules apply.
So straighten me out guys. Is direct drive causing the increase? And why do different lights with the same XML still put out different amps, such as 4 vs 5amp, if they are bypassing the driver???

Edited by: rdrfronty on 10/27/2012 - 08:45
cainn
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First of all, not all drivers are the same, and even in DD there’ll still be varying degrees of resistance between the battery and the LED.

Second, in cases where you’re seeing really high current draw with IMRs, it’s not that the driver goes into DD mode (that generally only happens with particular drivers when your battery is almost depleted) it’s that the driver isn’t current regulated at all. Whoever you bought the flashlight from was bullshitting when they said it was. IMRs are capable of putting out ridiculous amounts of current with comparatively low voltage sag under load. This explains what you’re seeing.

Edit: Oh, and could you be hitting the limits of your DMMs ability to accurately measure current anyway.

cainn
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Here’s a graph generated by HKJ’s battery comparator which illustrates the sort of thing that happens once you get beyond 3 amps:

IMR’s just keeping pumping out the current with much less voltage sag.

rdrfronty
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So basically these lights might be voltage regulated, but not current regulated. And therefore the high current allowing IMR really dumps some amps through the drivers on some.
Now on the C8’s I assume running in the 4.1amp range is pretty safe and should deliver about optimum power as long as they dont get too hot. I’m thinking that the HD2010 drawing 5.4amps likely isn’t safe and that it might burn up the LED in time. And I’m sure at that amperage it is producing so much heat it would be losing lumens correct? And the A60 with 2.4amps I’m thinking should be fairly safe, at least for 5-10 minute uses?
Obviously the L2 doesn’t need the IMR and I’ll keep the ET in there.
And one note about these lights – these ones are not EDC’s. They get used 80% of the time for playing around with and perhaps 20% of times for short usage of actual flashlight duty. So I’m not worried about runtime. Just don’t want to damage any of the lights by over driving or over heating them.

rdrfronty
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So at high draws the voltage can actually drop and therefore produce less power with a standard 18650. Thanks for the info. I guess I’ll be buying a couple more of the IMR’s.

scaru
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Yeah, I would not run IMR cells in the HD2010, 5.4 amps is going to probably have less output than say 4 amps. 

cainn
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rdrfronty wrote:
So basically these lights might be voltage regulated, but not current regulated. And therefore the high current allowing IMR really dumps some amps through the drivers on some.

They’re not voltage regulated either. In DD, the LED is simply getting whatever voltage the battery has to give it. In fact the higher the battery voltage is, the higher the current draw will be.

GottaZoom
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More watts comes from more amps and more volts. As cainn said, less resistance allows more current/amps.

Take one drop-in and use it in different hosts with the same battery and you can also see differences due to the resistance in the hosts.

Shadowww
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cainn wrote:
Here’s a graph generated by HKJ’s battery comparator which illustrates the sort of thing that happens once you get beyond 3 amps:

IMR’s just keeping pumping out the current with much less voltage sag.


Then again, some non-IMR’s are much more competitive than Panasonic 3100mAh based cells Silly

PS: and please don’t post JPG screenshots :3
cainn
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I chose the comparison I did because the OP said he was comparing against his Eagletacs, although I might not have picked exactly the right one in the battery comparator. But you make a good point.

As for the image type, hell, in this particular situation I’ll see your 22KB lossless png and raise you a 17KB lossless gif Silly

Shadowww
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cainn wrote:
As for the image type, hell, in this particular situation I’ll see your 22KB lossless png and raise you a 17KB lossless gif Silly
Not so “lossless” when it’s 256-color. Wink Silly
cainn
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10KB. You’ve started something now.

Shadowww
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On your 10KB pic, colors are distorted (some kind of purplish instead of blue) Silly

cainn
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Please don’t email HKJ and tell him that. I don’t want to get into any trouble.

MattSPL
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I have had the same findings with different lights and 18650’s.

Using a 1.4A P60, no matter which 18650 i used, i always measured 1.4A.

Using a 2.8A P60, i measured 2.4A with a Senybor(Panasonic) 3100mAh, 2.6A with an Enerpower+ 2900mAh 3C, and the full 2.8A with a Panasonic cgr18650ch IMR hybrid.

Using a 4.5A P60, i measured about 3.4A with the Senybor, about 3.8-3.9 with the Enerpower+, and 4.25A with the Panasonic cgr18650ch.

So it seems you really need a good quality low resistance cell for high powered lights.