Not the right amps on my meter.

[dj2rbo]

Hello. Something has been bugging me since I first started wiring up my sabers. When I check for the milli amps for the LED draw (wired in series) with the resistor on the store chart it never is correct. What I mean is when I use a 4aaa or 4aa batteries with a 2.2 ohm 5 watt resistor for a lux 3 blue green cyan it will only give it less than 700ma. Thus ends up making me always use a 1ohm 5 watt resistor for almost everything. I used new batteries but I don't understand why it's not giving me 1000ma. I know theres variations with the resistor but only by .1 or so not really alot. Anyways has anyone ever dealt with this or is my meter no good. Its an OTC multimeter and I never heard of multi meters needing of recalibration.

I also checked a 1000ma buckpuck with a Lux v and the max out of it is 820 ma. Shouldnt it be 1000ma? Well hopefull someone would help me out because I have only a few ideas to whats going on....

[Darth Xusia]

Multimeters can "wear out" and need recalibration. Any electronics repair shop should be able to do this.

[Rhyen Skytracker]

It will also depend on the voltage from the batteries. As the batteries lose voltage the current will drop if you use a resistor. This is Ohm's law at work. The buck puck works differently, as the current would normaly start to drop it increases the voltage to compensate for this. That is why buck pucks are more efficient.

[Jay-gon Jinn]

Make sure you have a fresh battery in your multimeter as well....that me look stupid recently when i was checking the voltage on my Trustfires.....

[Rhyen Skytracker]

Good point Jay-Gon. I have had meters give me bad current readings as well with low batteries.

[Sunrider]

There's no substitute for a Fluke. I've had my 87 for 15 years now, still works great. A worthy investment.

[Rhyen Skytracker]

Yep, I have a 87 too and it is awesome.

[neophyl]

The other point to remember is that at these low resistences (1-5 ohm) that you are discussing that putting the meter itself in series to measure current also increases the resistence slightly (more or less depending on quality of the meter) which can give a reading thats different to what you will get in use normally.

[Sunrider]

Yes. For the best measurement make sure your meter reads .1 or .2 ohms at most when leads are put together. They can oxidize over time & build up resistance.

[Novastar]

<--- loves it when Sun & Neo post, hehehh

It's true... I had forgotten about this just a little bit ago when I was REALLY trying to "dial in" a resistor setup. I wanted to yield a VERY specific setup for a clash flash resistor... and instead of ~3.3ohms, I needed ~3.

Well, idiot me forgot about the fact that my Retardo Montalban meter has some kind of fairly decent resistance over the leads. Like... oh, I don't know... 0.7? Anyhow... I wasn't getting what I needed until Erv & Don set me straight a bit better, lol.

But yeah, it's easy to forget that--yes--like all things... the meter creates resistance.