Sorry for the stupid questions, I’m new at this stuff…
Will putting a multi-meter across battery terminals give the max amps of the battery…?
Seems my 20b Samsung will give 5.7 amp reading across battery terminals.
But direct drive to a xp-l hi only draws 1.1 amps…?
Could small gauge (22gauge…?) wires only1.5” long do this…? What is the max safe amps a xp-l hi will draw…?
No, don’t do that. You risk damaging your battery and it won’t give you any meaningful measurements.
The 20b should be giving you 3+ amps. Small gauge wires will limit, but 22awg isn’t bad. Not sure why you’re getting such low numbers.
When you say direct drive, is it just the battery and emitter in the circuit?
Yes, direct drive connected to test. Only wire, battery, emitter in circuit.
And the DMM obviously. If that’s how you’re testing, either:
1. Your DMM is limiting the current itself (use thick, short leads. the ones that came with your meter don’t work well here)
2. Your DMM is lying about the current
3. Your battery is already damaged
4. Your LED is damaged
5. Any combination of the first 4
+1 I wouldn’t advice shorting out the battery. It won’t tell you anything meaningful, will likely break suff and is potentially rather dangerous.
Best way to find rated amps for a battery is to look them up. Either in manufacturer stats, or from reviews.
As for your case. Maybe you could describe in more detail or take a photo of your setup, so that we can see how you are trying to measure this exactly and with what components present.
Amp draw will also depend on the charge of the battery, a flat battery with a low voltage, will not be capable of delivering the same amps as it can when fully charged.
Along with what Pilotdog has said, do you know your battery is genuine? There are plenty of fake and dodgy batteries out there.
If you think your setup and equipment is ok, then do you have any other different brand batteries to try?
Thanks for the quick reply pilotdog68…
Just tried my industrial strength meter, with large test leads. Amps went up to 2.4 with 20b.
Tried a Klarus 2600 and got 2.3amps. tried a moli 2000(?) got 1.78amps.
Led is new, from Mtn. XPL-HI-V2-3B. On a Noctigon 20mm.
Tried another new xpl hi in a light and got similar. I am just bypassing the tailcap switch with meter leads, is that wrong…?
Guess I was forgetting about dc currents extreme loss over small conductors, like the test leads…
Thanks for straightening me out pd68… But why can’t I get more amps out of my emitters…?
Ya ,just found that out…
the large test leads meter goes off scale on the 20 amp range across the battery. Won’t do that again. Huge difference with small test leads/thick leads.
Well 2.4amps is closer to what I expect.
Neither of those batteries are top performers, but I think 3amps is still reasonable. I’m assuming you checked all of your solder connections to make sure they’re strong? Also, bad contact by the leads at the battery tube is sometimes the culprit
What do you mean by “large test leads”? Many of us switched to clamp meters because even with 4” 12awg leads in otherwise perfect conditions, you are still limited by the meter’s shunt itself. In some cases we saw jumps of 2+ amps after switching to the clamp. In reality though, we were already getting those big numbers when the light was fully assembled, we just couldn’t measure it.
The circuit is all limited by the Vf of the emitter at certain amp draws, and the voltage sag of the battery under load. Any extra resistance in the circuit (including the meter) will cause a lower reading.
That being said, there have been a few times where a particular emitter or particular batch of emitters just won’t do the high amps for whatever reason. I would try everything else before assuming that though, unless you can test the Vf of your particular emitter.
Got a few clamp meters also. mostly used for testing a/c current in motors/compressors etc… Looking at its functions not sure it does dc clamp readings. Its a uei g2. Got an amprobe meter also, got to take a look at it to see if it does dc. So my fluke mm with thick test leads will not be accurate, interesting stuff you guys found out, thanks for sharing. What clamp meter do you recommend…?
Looks like that clamp does DC voltage but not DC current. Many of us got the UNI-T UT210E. Discussion Here. Coupon and links here.
Obviously the fluke isn’t a bad meter, but the way they operate is to add tiny resistance to the circuit and measure the difference. DD and most of your drivers are very sensitive to this.
However, usually you only see those differences around and above 5amps, not 2-3amps. That’s why I asked about your leads, are they thick short pieces of wire, or are they still like 20-22awg with just a bunch of insulation to make them “heavy duty”? Even a cheap Harbor Freight meter should work fine under 4-5amps as long as you replace the leads with thick short wire.
And again, I don’t know much about the two batteries you are using, do you have any higher performance ones you can try? That could still be the issue too.
Are these LED’s in a an actual host/flashlight then?
If so, is there a driver in the flashlight?
My original leads were thick, but had 20 or 22awg inside. IIRC I measured 2.3A on 3.04A drivers. Upgrading to short 12awg I saw around 3A
Good info.
No had not checked my solder connections, but now that you brought it up, they look good, might go back and beef them up a bit and see what that does. Not use to this low voltage dc stuff, no wonder old Nicky Tesla went ac, lol
My thickest set of Test leads are probably #16-18,? hard to tell without stripping back the insulation. Diffidently not 12awg. Never seen 12awg test leads, but about to make up a heavy duty test lead set. I’ve got some #10 stranded copper wire. About to make a 6” long set of leads, just for a test.
Standard DMM leads might look fat, but usually have very little wire content.
e.g. leads like these:
When doing amp readings I used some leads I made up myself:
Which is just some RC car battery wire. If you tin the ends then they will stick in the DMM terminals fine.
Heavier gauge wire will have less resistance. So should show better results. Although I’m not convinced that is the issue in your example.
The leads are usually 20-24awg, sometimes it’ll be printed on the wire itself, but not always. I just went to Home Depot and bought some 10 or 12awg stranded copper outdoor/underground AC power wire. It’s pretty flexible and cheap.
Tested in a c8 light. And a modded zoomie. One is direct drive, other is a fet driver. Also did a quick’ test of a xpl hi emitter on a noctigon screwed in tight to a pill. All tested out to about the same amp draw with my new #10 test leads. Slightly different with battery used. All tested out to 2.2-2.4 amps regardless of battery used. No where close to the 5 amps I’d like to see, (suppose to see…?)
Well, that narrows it to either the batteries or the emitter
I still suspect your ammeter just has a high resistance. If you have another DMM, measure the voltage across the ammeter while the current is flowing. From this you can calculate the resistance of your ammeter.
In your original post, shorting the cell with the ammeter resulted in 5.7A flowing. If the cell was at 4V and had 0.03 ohms internal resistance, this means your ammeter had about 0.67 ohms resistance, which is very high when compared with the resistances of what is usually in the circuit. You have since changed the leads, but the meter itself still could have a high IR.
If 3 different emitters of the same/similar bins all test out more or less the same, chances are it shouldn’t be a faulty/damaged/defective emitter in all 3,? How can an emitter be tested if its defective…?
With the correct battery, maybe a 30q(?), what amp can I expect to see on DD xp-l hi v2 3b. What is max allowable(desirable) amps for a xpL hi, or a xm L2 …?
Thanks for the link to the dc clamp amp meter, ordered one. First clamp meter ‘I’ve’ seen that only did amps.
With a fully charged 30Q, between 4-5.5amps is to be expected in most cases.