I did something dumb (again)...what did I break?

[rudeguy]

So I was trying to figure out if my voltmeter was working and stuck one of the leads to the outer part of my laptop charger and the other to the inner part. Now my laptop won't charge.

My question is: Did I fry my charger (lappy still powers on with it plugged in) or did my battery just happen to die right after I did this? Or did I short something in the charger which in turn fried the battery?

Also...how the hell do I properly use a voltmeter on DC? I know how to use them on cars...just not for home use.

 

[lxskllr]

To test the charger, switch your multimeter to DC voltage, and touch one lead to the center position, and 1 lead to the outer. Polarity doesn't matter, but it'll read -Volts if you have them reversed.

 

[PieIsAwesome]

Not sure.

Is this a multimeter and was it correctly set to read DC? If it was set to read current it could have caused a short?

Voltmeters are supposed to be connected in parallel to a circuit, not in series with a current running through it.

 

[rudeguy]

To test the charger, switch your multimeter to DC voltage, and touch one lead to the center position, and 1 lead to the outer. Polarity doesn't matter, but it'll read -Volts if you have them reversed.

what if I did something similar to that and sparks shot out? Maybe it wasn't set to DC??/

 

[lxskllr]

what if I did something similar to that and sparks shot out? Maybe it wasn't set to DC??/

Hmm... Sparks came out of the charger barrel, or the multimeter? If you had it set on impedance that could have affected something. That puts out a small amount of voltage(usually from a small battery), and the charger might not like that. I'm not an EE or anything, so I'm not sure.

 

[rudeguy]

Yeah...came out of the charger.

I'm going to set the voltmeter to DC and see what happens. If I'm not back in 15 minutes, order pizza

 

[Number1]

Does the laptop indicate it is charging but the battery won't hold the charge?

To measure DC voltage, set the knob to DC and make sure the leads are connected to the common (COM) and voltage (V) connectors on the voltmeter.

 

[rudeguy]

that was interesting. I put the positive lead on the outside of the lappy charger and the neg on the inside. About half of the positive lead melted off.

 

[Rubycon]

What's the model of the notebook/charger and what kind/model volt meter is this?

Many chargers are "smart" and can report to the charging circuit on the PC as to their ID - chiefly capacity. Unidentified chargers are just left to provide power to the motherboard allowing the computer to run but NOT charge the battery pack. Doing both requires higher capacity, etc.

It's possible that your charger just needs to "bleed down". Unplug it and let it sit for an hour. During this time also remove the battery pack from your notebook. Re-install the battery pack, plug in the charger to a wall socket, connect the cord to the notebook and boot up. If it still is not charging the adapter may be damaged.

Meter type matters too! Most digitals - even the $5 Harbor Freight cheapies - have a high enough impedance not to affect most circuits including battery chargers. Examine the plug closely with a magnifier if possible. A jeweler's loupe works great! There may be more than one conductor internally and your meter's test lead could have shorted them together! This condition of anomaly SHOULD be cleared by "resting" as previously discussed above.

Meters you do NOT want to use are non FET/VT analog ones as they will cause interference with circuitry. Generally a battery charger is pretty rugged but these are not your typical wall wart.

that was interesting. I put the positive lead on the outside of the lappy charger and the neg on the inside. About half of the positive lead melted off.

Are you sure your meter is not set / leads plugged in - to measure current (A) instead?!

 

[rudeguy]

Are you sure your meter is not set / leads plugged in - to measure current (A) instead?!

They are...oopsie

On a bright note, its charging again


So what exactly did I do??

 

[Rubycon]

They are...oopsie

On a bright note, its charging again


So what exactly did I do??

Just created a short and tripped protection. You've confirmed the protection is working. (and you should be more careful with a multimeter! If that were line voltage...)

 

[rudeguy]

Just created a short and tripped protection. You've confirmed the protection is working. (and you should be more careful with a multimeter! If that were line voltage...)

LOL...that's the bad part of learning about this stuff on cars. I have zero fear of getting shocked.

Besides...if I do anything too bad, the circuit breaker will trip, right?

 

[Rubycon]

LOL...that's the bad part of learning about this stuff on cars. I have zero fear of getting shocked.

Besides...if I do anything too bad, the circuit breaker will trip, right?

Most meters have two ranges - a low range up to 1A sometimes less that has a fuse. The high range typically 10A sometimes 20A (!) that is unfused. If you are connected to this and place the probes in a wall socket you will definitely see a nice spark, the branch circuit protection should open immediately but even still your lead tips will probably be nice and eroded from the fault. If the overcurrent protection fails (Federal Pacific Electric aka STABLOK mode!) then the wire will heat up real fast, you will get a torrent of sparks and probably need a change of underpants.

 

[GodlessAstronomer]

LOL...that's the bad part of learning about this stuff on cars. I have zero fear of getting shocked.

Never been on the receiving end of the hot side of a coil?

 

[rudeguy]

Never been on the receiving end of the hot side of a coil?

Not that I remember. The worst was one of our shop lights had a fray in the cord and that spot hit the puddle I was standing in. Weirdest feeling ever.

I don't know how many times I changed out positive battery terminals and ended up arching the socket against the block.

 

[Rubycon]

RE: Flooded batteries...

Careful around them! Sparks can ignite hydrogen gas and if the top blows off spraying sulfuric acid in your face and banging your head with shards of plastic you will be sorry!

High energy ignition systems can definitely light you up too!

 

[BoomerD]

Never been on the receiving end of the hot side of a coil?

"Here, hold this wire while I try to start the car."


Both my kids...and my wife learned the hard way not to trust me...

 

[rudeguy]

"Here, hold this wire while I try to start the car."


Both my kids...and my wife learned the hard way not to trust me...

Ever mess with a horse fence? I'm surprised I didn't melt some filings as many times as I grabbed that thing.

The worst thing was the electric fence dog collar. That mother hurt like nothing I've ever felt before.

 

[GodlessAstronomer]

"Here, hold this wire while I try to start the car."

I fell for that one once. It's a right of passage in the industry

 

[Rubycon]

The worst thing was the electric fence dog collar. That mother hurt like nothing I've ever felt before.

Wuss!

Those are like a static shock from walking across a rug and touching a doorknob.

If you really want to get "snapped" get charged on a Van deGraaff where your hair really stands up...

and then touch a grounded object! If the air is dry you will get a spark several INCHES long, there will be a loud POP, a faint smell of singed flesh and your hand will hurt bad!

 

[disappoint]

Is that you in the pic Ruby?

 

[Modular]

"Here, hold this wire while I try to start the car."


Both my kids...and my wife learned the hard way not to trust me...

Failed assassination attempt, eh?

 

[Rubycon]

Is that you in the pic Ruby?

LOL, no.

 

[Matthiasa]

Yes multimeters are fun... I made a nice loud bang and fun sparks(molten copper that I still have on some stuff) when measuring stuff once while measuring voltage no less.
Yeah wall voltage is a tad dangerous, and it was the wires in the cord I bought that I was testing, since yeah needed it for a small transformer which was for a project...
Meaning I now have like a ~$20 hot plate that takes forever to heat up.

 

[nsafreak]

Wuss!

Those are like a static shock from walking across a rug and touching a doorknob.

If you really want to get "snapped" get charged on a Van deGraaff where your hair really stands up...

and then touch a grounded object! If the air is dry you will get a spark several INCHES long, there will be a loud POP, a faint smell of singed flesh and your hand will hurt bad!

Stop giving him ideas! Next thing you know he'll try and do something really silly like build a jacob's ladder.