Did I fry my multimeter?

[river251]

I have a Craftsman 82400 autoranging multimeter I've had for some time.

I went to check my car battery's voltage today. I put the + lead in the 20A connecter. Then I stupidly contacted the battery's posts backwards....+ on -, - on + for a second. Saw a little spark at the battery.

I then contacted the battery correctly, and just saw - 0000.0 volts. No matter what I do I see 0 volts, and if I switch to mV, still just - 0000.0.

I have used this on batteries before with no problem I believe.
I took both fuses out and they both look good. The filament is tiny but it looks solid end to end.

Any clarification would be greatly appreciated. Thanks for reading.

Jim

 

[ven]

Hi Jim,dont know much on your meter but there should be a fuse in it or sometimes in leads.

Sorry -edit- just read you checked fuses.........i had read it but not taken in:shakehead

 

[880arm]

At the very least it sounds like you had the meter configured wrong and there's a good chance you blew the fuse. The 20A jack is used only for measuring current, not voltage or anything else. The spark didn't have anything to do with getting the +/- backwards.

For checking voltage the black lead should be in the center jack which is marked "COM." The red lead would be connected to the right-hand jack which is for testing voltage, resistance, and very low levels of current. Even if the fuse is blown, you can still test for voltage if you make the connections as described. You can also test the fuse by measuring its resistance.

 

[river251]

Thanks guys. Then I'm baffled. I just charged my battery yesterday. Today when I turn the key, absolutely nothing. But the battery, brand new, can't be reading zero voltage. ???

Well at least I now know I need to keep the red in the right. And I tested a AA and it read 1.5ish. So I'll go back and start tracing voltage and see what I find.
Thanks.

 

[880arm]

Have you rechecked your car battery since you changed the connections on the meter? If your meter is working properly with the AA battery and still reads a flat zero on the car battery then there must have one heck of a load left on when the engine was shut off. Headlights?

 

[PhotonWrangler]

From the owners manual for this meter -

Fuses mA, μA ranges, 0.5A/250V fast blow
10A range, 10A/250V fast blow

There is a separate door for the two fuses that is secured by a screw. They are user replaceable (not soldered in).

 

[hazza]

I would be very surprised if you didn't blow a fuse doing this. Never mind how they look, I think you need to continuity check them.

With the probes in the A and COM ports, the impedance through the multimeter is extremely low (as it is designed for a series measurement). When you connected it across the car battery I would expect a very large current flow, certainly enough to take out a 10A fast blow fuse.