Multimeter operation question...

[Zenmachine]

I have been using a multimeter for various testing for a good while now, however even after reading instruction manuals, and buying a second unit, I still barely know how to use this thing.

My first one stopped measuring DC Volts after somehow misusing it on a car battery, so I bought another one. And this one refuses to test continuity what-so-ever, and neither of them has ever been able to measure amps. (Measuring amps for me normally ends up in some type of smoke coming out of the unit or nothing at all) I'll admit neither of them were expensive units (both from canadian tire) but there has to be something im missing.

What my main question is (FCM :p), I understand that one side of the three possible connections for the probe is fused, and one is un-fused? One side says its good up to 750ma and one says its good up to 10 amps? If a car battery can put out hundreds of amps in short bursts, what side can I use?

Im pretty much guessing the second one I just bought wont test continuity because its faulty (the last one was easy, turn the dial to the squigily line, and it makes a sound if there is continuity...The only way new will make any kind of sound is if you smash it with a hammer ), but how do I test amps and stop blowing these things up?

Sorry for the long post, maybe if you know a website I can reference or something to help me understand just how the hell I am supposed to use these things that would help.

Thank you.

[fcm]

You can not test for current, [amps] on loads that use more then 10 amps, with the meters you are using.

However if you overload the meter the fuse should blow, you should not be burning the meter up, so either you connected wrong or meter was defective, what exactly do you want to do, test for? 94

http://www.doctronics.co.uk/meter.htm

[Zenmachine]

Well, im trying to bring car batteries back to life using a variety of chargers I have lying around the house. I have had good success and been reading non stop about proper voltages/currents for different stages of charging and although I can monitor my voltages ok, I wasn't able to ever get a reading for current.

I understand what you are saying about the internal fuses blowing, I imagine that's what happened in the last meter and why it would no longer measure dc volts...I believe I tried to use the "load test" on a cheap multimeter and I understand those are neither accurate nor effective. With the meter I am using now though, yesterday I moved the red plug to the "fused up to 10 amps side" and tried to get a current measurement from the 5 amp charger and voila..smoke starts coming out of the meter.

Basically I am trying to monitor weather the charge current is tapering off as the battery reaches full charge or not, thusfar with no success.

Thanks for the link I will check it out.

I do have one more question FCM, I am very interested in learning all about circuit boards, how to build them, and how it all works and I wonder how someone learns what you know? I realized you have worked your whole life in the industry but Im curious how someone like me goes about learning this stuff. I have no interest in becoming an electrical engineer, I just wanna know how to build a simple circuit and have a good general idea of how this stuff works. Did you take courses or learn everything on the job?


*EDIT* That link was very helpful and answered a few questions I had. I'm figured out how to properly test for current thank you, although now I see how limited this multimeter is. I can test for less than 20mA, less than 200mA or less than 10A. If the current value is something like say 400mA it just tells me its less than 1...Not super helpful.

I also bookmarked the page and intend on doing their online course so I dont have to bug you with all my silly questions forever. :p

[fcm]

This is what we use...
http://buy1.snapon.com/products/diag...MT3750KRBC.asp

This is the other one we have...
http://www.ferretinstruments.com/Ferret/40/40.html

Most of what I know is because of how long I have been doing it, I have taken any courses offered by employers.

Now you can Google up anything you want to know/learn. 94

[lksdG2]

damn that snap-on one is nice!

we have two mac ones like the ferret we use at work

[Zenmachine]

Yes those are nice rigs, however the chargers I am using and wanting to make are near free. That snap-on one looks like I would have to sell the car to be able to buy it.

So far so good though on my revival attempts. I have brought one battery back from the dead using a series of different voltages and currents and extended the life of another. Its amazing what a little knowledge and proper charging will do to a car battery...Well any battery really, especially lead acid and ni-cad's but li ion as well to a certain extent.

Anyway thanks for the info as always FCM, I'll keep studying in my spare time and see what I can learn. Besides, someone has to do this, your not going to put up with our nonsense forever are you..:p


P.S. I hope you are enjoying your sunny 11 degree weather, we got hit with a HUGE blizzard in NL last week. I miss BC a little in times like this.

[lksdG2]

Yes those are nice rigs, however the chargers I am using and wanting to make are near free. That snap-on one looks like I would have to sell the car to be able to buy it.

So far so good though on my revival attempts. I have brought one battery back from the dead using a series of different voltages and currents and extended the life of another. Its amazing what a little knowledge and proper charging will do to a car battery...Well any battery really, especially lead acid and ni-cad's but li ion as well to a certain extent.

Anyway thanks for the info as always FCM, I'll keep studying in my spare time and see what I can learn. Besides, someone has to do this, your not going to put up with our nonsense forever are you..:p


P.S. I hope you are enjoying your sunny 11 degree weather, we got hit with a HUGE blizzard in NL last week. I miss BC a little in times like this.

hahaha good point

[fcm]

It's only sunny and 6 degrees C today. 94