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guess your thick headedness is bliss to you..good night
I guess ignorance really is bliss.
guess your thick headedness is bliss to you..good night
Yes, I am thickheaded because I know from personal experience that hooking a DMM up to a battery and measuring resistance will NOT blow it up. You'll get a reading of the internal resistance of the battery, which is indicative of the storage capacity/health of the plates within the battery. It's more complicated than that, but this doesn't even have anything to do with the topic, so I won't even bother to explain.
I'm done here.
riiiiiiiiiiiiiiiiiiiiiiiiiight....
I love Internet fights...they're liking pissing yourself in a dark suit....you get a nice warm feeling but nobody notices...
Chip
2000 Basalt Black Metallic GTZ
(Paint Code: Porsche LC9Z)
Genuine experience carries a lot more credibility than the ability to answer a question.
Where's the bullshit warnings when you need them
But seriously, the meter won't fry from doing that, unless it was shitty to begin with
~Lady Driven~
ok whatever you experts say
Indeed.Originally Posted by fliegendaffe
~Lady Driven~
sarcasm
Try to keep it civil and on topic fellas and ladies.
I have connected my MM to the positive terminal on my battery and nothing happened except the MM read the voltage of the batt? Am I missing something?
7g for life!
Nope, you are right on Seth. That's exactly what should happen. I've done it with two different multi-meters and both of them are fine.
222whp/250wtq
I could understand if the OP was taking the MM and directly switching to measuring current, yes, in that case you would fry the MM if you didn't put out the cash for one with a fuse built in. You said it yourself, he wants to measure VOLTAGE DROP, also known as RESISTANCE. Measuring the voltage in those two different locations WOULD give a voltage drop, but doing so is unnecessary.
Remember the ground is often referred to as what? The reference node, and as such it is referenced as 0v. Now what about this 0v? Ohm's law right? V=IR? Measuring across the ground and back to the negative should net you close to 0 ohms of resistance ie. voltage drop.
Anyway what you're saying about the current IS correct in a sense, but that would require the OP to switch the MM to measuring amperes. What happens when you try to take ......
12v
----
0 ohms
= DNE..Right? Well technology isn't that damn smart and generally u have some retarded 0.00001 ohms of resistance resulting in a massive current reading (basic math yo) and frying the MM. Basically, he would have to be trying to measure the current to blow that thing unless there's some other strange issue.
In short...
Warm is right...EEGR major, although that means absolutely nothing. Theory and experience in labs and real situations is another issue as I learned from my internship.
Last edited by bmore303; 02-21-2008 at 10:20 PM
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ok here we go...lets correct all of you.
first of all. there is no formula that is v=ir. I think u mean e=ir. secondly, that is not ohms law, that is kirchoff's voltage law.
then to get a dmm that has a fuse on 12 v setting would cost you hundreds of dollars.
do any of you guys actually understand a 12v dc systems? cuz it doesn't seem like it.
by connecting the 2 battery posts guess what you make? yup, a short circuit.
lastly, do any of you know who Derek Lee is?
Wow, I really am convinced you have no idea what you're talking about. Ohm's law IS V=IR. Voltage (V) is Resistance (R) multiplied by Current (I).
Kirchoff's voltage law simply states the the overall electrical potential of a system must be 0. Nothing more than a derivative of the conservation of energy.
I really hope you do realize that what you're saying is that it's stupid to use a volt meter or DMM to measure the voltage of your battery at the posts - this is complete blasphemy. How do you think most intelligent battery chargers work?
And what does the last question you ask have anything to do with what we're discussing? You're trying to bring something unrelated up in a desperate attempt to make at least one of us look stupid. GG argumentative fallacy. No, I don't know who that is relative to any of what we're talking about.
Last edited by WarmAndSCSI; 02-21-2008 at 11:57 PM
actually the currect formula is e=ir. and the true ohm's law is p=ie.
the reason why battery chargers work like that is because of how they are wired.
and actually the last question is very relivent. maybe u should go find out who it is.
Okay, you are completely talking out of your ass. E and V are the SAME DAMN THING. It's just semantics. P=VI describes the power dissipated by a resistor given a certain amount of current. Definitely not Ohm's law. The combination of P=VI and V=IR gives you Joule's first law.
No, intelligent battery chargers (digital) work just like multimeters in that they measure the drop in voltage at the end of the charging cycle. It's not because of "how they're wired." Again, it's like you're talking out of your ass.
And why don't you just tell us, if it's so "relivent."
actually I am not talking out of my ass. first of all, V is not how it is represented in the formula anywhere but yes it is the same as E. secondly, it is how they are wired.
and thridly, i'll be an ass and tell your idiot self to go look it up. but give u a hint, he is one of the most well known car audio/electronic people out there, and I deal with him on a daily basis. he is my mentor
You're contradicting yourself. You say the formula is E=IR and that E and V are the SAME THING, yet you are saying that V is not represented in the formula. I dare you to make less sense.
Digital battery chargers have an IC programmed to look for a particular pattern in voltage drop. It's far from "wiring"
And I'm glad you have an awesome mentor... How on earth is this relevant to your own personal knowledge? And check yourself before you call me an idiot ever again.
tell you what, im coming in on this a little late and could simply flood this thread with technobabble to make your eyes and ears bleed because...... like mentioned before, experience is the majority of knowledge. thats why most engineers who havent wrenched on anything make things that are not very maintenance friendly.
now my experience comes from seven years of being an electrician on F-16's and am now the lead technician for the entire unit here in Iraq because of it. so in short i will tell you that the only way to "blow up" a multimeter is to put it on a circuit that is extremely out of its range or provide it a current flow that should make 20gauge wire red hot. at the same time the current flow or draw that is provided through a simple 12v automobile circuit (yes simple because thats what it is comparitively) will not "blow up" a MM especially if the circuit is not active. how many static hertz do you think this car's electrical system makes because i gaurantee you that he is not taking these readings with the car on. no one is saying that what you were taught is wrong but maybe your interpretation of the imformation is a bit weak. some people get different stories from the bible but the writing really doesnt change. get me?
What bmore and warm said are correct. You might want to find another mentor because some of your logic of how things work is a little off unfortunately. I just had to learn all of these formulas because of the projects I'm working on, one thing that kind of bothers me that you swear V=IR doesn't exist. You wouldn't work on my car lol. About the multimeter, what bmore stated is correct. And even with the extremely rare chance of it 'frying', what's wrong with getting another one?
~Lady Driven~
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