help with a multimeter

[leannebug]

(I know this might not be the right forum for this, but I think yall are the brains of ECF)

I just bought a multimeter (from harbor freights) to test my batts and such, but the directions are like walking through a maze. I have a few basic questions for using it, and hope yall can help!



1. where are the positive and negative ends on a regular sized battery? ie: 510, ego, etc..

2. there are umpteen warnings throughout the instructions. Is it that dangerous for small testing, like on PV's? Or just for bigger household instances?

3. one of the biggest contridictions : it refers several times to pluggin in the red plug first, then the black (COM) ... however, under the battery testing section it says: "Connect the common (COM) test lead first and disconnect it last" .... is that referring to the part I touch to the battery (not the plugs that pop into the unit)?

4. under battery testing, it says "Do not test current on circuits higher than 200 mah"... well if that's true, then what good is this thing?

5. it refers to both "turning off the power" ... well I can't do that unless I drain the battery first, right?
and
6. not to use in series... this probably wouldn't be something I'd use it for, right? (not just my little batts and my mod batts)

and last question deals with testing ohms.

How do I do that???


TIA for any help!

 

[MickeyRat]

That's what you get for reading instructions. The positive on those batteries is the post in the center. The negative is the threads on the outside. I've never used one to test an eGo or 510. I have used one to test a 510 connection on a box mod. I had to get my wife to hit the fire button. Most people on here mod an atty to give them a better way to hook to it. I suspect the warning about MAH is covering their .... in the case of an unprotected Li-on cell doing something spectacular. I've never really worried about which lead gets hooked up first. Maybe someone can tell me why it makes a difference.

 

[cskent]

1. the positive battery connection is the center post in the connector, the negative is the threaded part
2. it's not dangerous to test low voltage devices such as e-cig batt's, the warnings are there for higher voltage use such as 110v, 220v, and such.
3. it doesn't really matter which one you plug in first.
4. I don't know what meter you've got but it should be able to test many amps at the voltages we're talking about with e-cigs
5. You'd turn the power off if that were an option, for batteries you don't have to worry about it.
6. I don't understand the question.
7. to test ohms set your meter at the lowest ohm range, check to see if it reads zero by putting the leads together and get a reading, if it's not zero just subtract the reading from your measurements, or use the zero button with the leads touching, if your meter has a zero button. To take a measurement put one lead in the center of your atty and the other on the threads. It can take a little while sometimes for the reading to settle down.

I've got one of the cheap Harbor Freight meters that I picked up for $1.99 on sale. It works but it doesn't have a zero button. For checking voltage I use the DC range and set it at 20v, for ohm's the lowest I've got is 200 ohms. It takes about 30 seconds for the ohms reading to settle.

 

[leannebug]

Thanks for the replies!

I didn't *think* I had too much to worry about, but had to make sure.

On the questions, it cost about five bucks so maybe I have the advanced version? lol
Question 6: it references in a couple places about testing batteries in series and being extra careful or not doing it. I just wanted to make sure that didn't apply to me, in this instance.

Oh. The ohm testing: it doesn't matter which lead I hook up to the post? Or does it?

Thanks again!
Sent from my pod

 

[JackOnan]

3. one of the biggest contridictions : it refers several times to pluggin in the red plug first, then the black (COM) ... however, under the battery testing section it says: "Connect the common (COM) test lead first and disconnect it last" .... is that referring to the part I touch to the battery (not the plugs that pop into the unit)?

correct - it refers to the probe end - if you'll pardon the expression Doesn't really make a difference at low voltage of batteries.

4. under battery testing, it says "Do not test current on circuits higher than 200 mah"... well if that's true, then what good is this thing?

This would be for using the ammeter to measure current on the low ranges. Some of these meters have an extra jack on the front marked "10A" which is for measuring high current. You probably won't be using the ammeter section anyway, so don't worry about it.

5. it refers to both "turning off the power" ... well I can't do that unless I drain the battery first, right?
and

This could be for measuring resistance. Never measure resistance when the circuit is powered on. So, if you're measuring the resistance of an atty, make sure the atty is disconnected from any power source first. It could also refer to testing a battery while its still in the device. Make sure the power to the device is turned off. I'd remove the battery from the device for testing if you can.

On the questions, it cost about five bucks so maybe I have the advanced version? lol

Is it the little red one? Usually its 4.99 but sometimes on sale for 1.99.

Oh. The ohm testing: it doesn't matter which lead I hook up to the post? Or does it?

It shouldn't matter for an atty. Just be sure not to connect the leads to a battery when the meter is set to measure resistance - this can damage the meter.

 

[leannebug]

This could be for measuring resistance. Never measure resistance when the circuit is powered on. So, if you're measuring the resistance of an atty, make sure the atty is disconnected from any power source first. It could also refer to testing a battery while its still in the device. Make sure the power to the device is turned off. I'd remove the battery from the device for testing if you can.


Is it the little red one? Usually its 4.99 but sometimes on sale for 1.99.


It shouldn't matter for an atty. Just be sure not to connect the leads to a battery when the meter is set to measure resistance - this can damage the meter.

Yep.. it's the red one (with the additional plug hole.. that I won't be using)

OK. question: you say I should turn off the battery (I get that for mods) but the only way to test the smaller batts (ego, etc) is to fire it.. so isn't that contradictory??


Thanks again.. appreciate yall taking the time to help someone so lost!

 

[TomCatt]

The instructions saying to turn off the power, may be referring to using the meter to measure AC, i.e. house wiring; and not DC - batteries.

 

[Silent Soldier]

gah, I was gunna get that voltmeter but the dang shipping is more than the item!

 

[leannebug]

Check the website for a local shop Soldier. I didnt know I had one.. (a Tractor Supply Store too!)

 

[JackOnan]

The instructions saying to turn off the power, may be referring to using the meter to measure AC, i.e. house wiring; and not DC - batteries.

Heh, the only problem with this theory is that if you turn off the house power, you won't be able to measure AC! DOH! But you may be right if they are talking about measuring batteries in a dual power device. In that case, it would be necessary to disconnect any AC power in order to test the batteries properly(thats if you're going to leave them in the device).

 

[Animeguy]

Walmart sells em at 15-20 I think thats what I got.

 

[JackOnan]

Yep.. it's the red one (with the additional plug hole.. that I won't be using)

OK. question: you say I should turn off the battery (I get that for mods) but the only way to test the smaller batts (ego, etc) is to fire it.. so isn't that contradictory??

Well, you're not really turning off the battery, you're turning off the device. In the case of the eGo batteries, since there isn't an easy way to remove the actual battery from the enclosure and support circuitry, disconnecting the atomizer(removing the load) would be sufficient. The idea here is to remove any load(or external power source) from the battery which would affect the reading.

 

[CraigHB]

4. under battery testing, it says "Do not test current on circuits higher than 200 mah"... well if that's true, then what good is this thing?

Still a lot of good actually. In electronics, you typically don't read current directly. You're mainly concerned with voltage, though there are still stituations where you want to measure current directly. Most cheap DMMs do not have the capability to read current which isn't a problem because you would typically take a voltage measurement then find the current by dividing out the resistance.

I use a fairly high-end professional DMM. It has a seperate lead plug and dial setting for currents up to 400mA and another plug and dial setting for currents up to 20A. I do measure current on ocassion and you have to be careful when doing that. When measuring voltage, you're connecting the test leads in parallel. When measuring current, you're hooking up the test leads in series. If there's a short in your circuit, or you are not paying close attention when probing, you can get large currents flowing through your meter. Don't know about the cheapie meters, but my professional one has fuses on the current testing circuits and I've blown the 400mA one a few times. I keep a handful of those fuses on-hand.

 

[Stosh]

I have a Harbor Freights "little red one", and can say there is no zero button for Ohms, so you do need to subtract the reading you get from touching the leads together.

Measuring voltage is straight forward, dial to DCV 20 and put a lead on each end of the battery, either lead to either battery end.

You can measure amperage with it but that gets tricker, meter needs to be wired between the battery and atty.

I was checking amps for clearos on a variety of power sources about a week ago. Was working up a spreadsheet of actual amperage for different cartos / attys with different power. But then needed the battery connector for a box, (ordered more from MV)

 

[MadmanMacguyver]

ok 1) testing current is not something you need to do
2) set your multimeter to 20 VDC for testing your batts...DO NOT USE THE BATTERY TEST FUNCTION!!! that will kill your meter and maybe mess up your stick batt...
3) put the red lead from your meter to the center post of the batt,the black to the outside edge...(be careful if they touch while you are pressing the button you could kill the batt...

4) get frustrated and buy a meter that screws onto the battery connector and bypass the whole thing...lol

5) no really get a dead clearo and screw that into the end of your batt buy a pair of alligator clips and plug your test leads from the meter into those...(alligator clips...)clip red lead(with alligator clip)onto the center post of the clearo...clip the black lead (with alligator clip) to the base of the clearo(yea I know tight fit) then push the button on your battery w the meter set at 20VDC...Easiest way I know...

PS pardon my poor attempts at humor I have none...lol

 

[Para]

ok 1) testing current is not something you need to do
2) set your multimeter to 20 VDC for testing your batts...DO NOT USE THE BATTERY TEST FUNCTION!!! that will kill your meter and maybe mess up your stick batt...
3) put the red lead from your meter to the center post of the batt,the black to the outside edge...(be careful if they touch while you are pressing the button you could kill the batt...

4) get frustrated and buy a meter that screws onto the battery connector and bypass the whole thing...lol

5) no really get a dead clearo and screw that into the end of your batt buy a pair of alligator clips and plug your test leads from the meter into those...(alligator clips...)clip red lead(with alligator clip)onto the center post of the clearo...clip the black lead (with alligator clip) to the base of the clearo(yea I know tight fit) then push the button on your battery w the meter set at 20VDC...Easiest way I know...

PS pardon my poor attempts at humor I have none...lol

I really hate the clips and leads and trying to hold something while making sure there's contact, etc. The meters are SO cheap and we constantly check battery and atomizers; spend an hour making a setup for testing each.

When you need to check an atomizer...just

Screw it in the connector and check the ohm reading

Do the same with an old battery charger. Wire the leads in the tray for + and -. The meter is already set for 20v so all you do is turn on the meter and check the reading.

Probably a wash on time to actually check, but again; I hate the clips and leads....seems like I always need a 3rd hand

 

[leannebug]

Still a lot of good actually. In electronics, you typically don't read current directly. You're mainly concerned with voltage, though there are still stituations where you want to measure current directly. Most cheap DMMs do not have the capability to read current which isn't a problem because you would typically take a voltage measurement then find the current by dividing out the resistance.

I use a fairly high-end professional DMM. It has a seperate lead plug and dial setting for currents up to 400mA and another plug and dial setting for currents up to 20A. I do measure current on ocassion and you have to be careful when doing that. When measuring voltage, you're connecting the test leads in parallel. When measuring current, you're hooking up the test leads in series. If there's a short in your circuit, or you are not paying close attention when probing, you can get large currents flowing through your meter. Don't know about the cheapie meters, but my professional one has fuses on the current testing circuits and I've blown the 400mA one a few times. I keep a handful of those fuses on-hand.

I wish I could understand... unfortunately, this all went <swoooooooooosh> over my head. :/

Well, you're not really turning off the battery, you're turning off the device. In the case of the eGo batteries, since there isn't an easy way to remove the actual battery from the enclosure and support circuitry, disconnecting the atomizer(removing the load) would be sufficient. The idea here is to remove any load(or external power source) from the battery which would affect the reading.

Thanks for clearing that up.

ok 1) testing current is not something you need to do
2) set your multimeter to 20 VDC for testing your batts...DO NOT USE THE BATTERY TEST FUNCTION!!! that will kill your meter and maybe mess up your stick batt...
3) put the red lead from your meter to the center post of the batt,the black to the outside edge...(be careful if they touch while you are pressing the button you could kill the batt...

4) get frustrated and buy a meter that screws onto the battery connector and bypass the whole thing...lol

5) no really get a dead clearo and screw that into the end of your batt buy a pair of alligator clips and plug your test leads from the meter into those...(alligator clips...)clip red lead(with alligator clip)onto the center post of the clearo...clip the black lead (with alligator clip) to the base of the clearo(yea I know tight fit) then push the button on your battery w the meter set at 20VDC...Easiest way I know...

PS pardon my poor attempts at humor I have none...lol

(thanks for the tip on the clips.. have to pick those up next time I go to Lowes) Now this is where I'm getting confused.. Isn't that contradicting each other? Don't I NEED to use the battery function to test the batteries? What am I missing? If I don't use the 'battery mode' what mode do I use to test the batts?

I have a Harbor Freights "little red one", and can say there is no zero button for Ohms, so you do need to subtract the reading you get from touching the leads together.

Measuring voltage is straight forward, dial to DCV 20 and put a lead on each end of the battery, either lead to either battery end.

You can measure amperage with it but that gets tricker, meter needs to be wired between the battery and atty.

I was checking amps for clearos on a variety of power sources about a week ago. Was working up a spreadsheet of actual amperage for different cartos / attys with different power. But then needed the battery connector for a box, (ordered more from MV)

Good to know!

I doubt I'm be checking amps.. have just started to get all the mahs and ohms worked out, and just want to see.....
1. when my batts are getting low and need tossed and
2. check ohms on attys if I get them mixed up.
... pretty basic stuff.

 

[CraigHB]

I wish I could understand... unfortunately, this all went <swoooooooooosh> over my head.

Sorry, tried to keep it simple, but with no understanding of current, voltage, and resistance, it's hard to explain. You might went to read up on Ohm's Law.

If I don't use the 'battery mode' what mode do I use to test the batts?

Much like using Ohms to test atties, you use Volts to test batteries. If the voltage is under a threshold, the battery needs to be replaced or recharged. Of course, you need to know the value. It depends on battery chemistry. For Li-Ions, they come off the charger at 4.2V and need to be recharged around 3V.

 

[bstedh]

Yea, you do really need to have a basic understanding of DC circuits, even simple ones, or everything is probably going to sound like Greek =]
You can pick up a lot of knowledge just by doing some basic google searches and lots of reading of web sites and posts. I think I am going to look for some websites that have some really basic information that will apply to what we are doing and post them as a DC electronics 101 for the un-initiated. I think that would help a lot of people that have never been exposed to this until they started playing with their PV's.

The most important though as stated previously is obtaining a good understanding of Ohms law and slowly working your way to E=MC2...

 

[bstedh]

here is a pretty good vid on how to use your multi meter
YouTube - ‪HD Multimeter tutorial‬‏

one checking the voltage of a PV
http://www.youtube.com/watch?v=UpTXGvCCmKE