Problem with multimeter

[NatureBoy]

Wasn't sure where to post this.. but I'm trying to test my coil, so I figured I'll post it here.

Anyway, picked up a freebie Centech multimeter at Harbor Freight today. Used it to check a battery, worked fine. Tried to test the resistance of a coil I made, and it was jumping all over the place. It eventually settled on 4.0 (meter set to 200ohms). I've tried touching the probes together to test the internal resistance, but the reading just jumps all over the place, never settles on a number.

Is this meter toast, or am I forgetting something?

 

[Sicarius]

Maybe the battery is running flat. Can get weird readings if it is on its way out.

 

[ScorpioZZZ]

One of your leads might be bad or a bad connection. I would take one out and see if you can stick the tip from the one in the meter into the empty connector for the other lead and see if the ohms measurement settles down. Test both leads......

 

[NatureBoy]

Maybe the battery is running flat. Can get weird readings if it is on its way out.

This one doesn't take a battery...

 

[NatureBoy]

One of your leads might be bad or a bad connection. I would take one out and see if you can stick the tip from the one in the meter into the empty connector for the other lead and see if the ohms measurement settles down. Test both leads......

Ok, tried that. Each lead showed 0.8. Then plugged both back in and tested again, once settled down it stopped at 1.2. Now it seems to be working fine. Strange!

Thanks for the tip...

So the coil reads 3.2. I subtract 1.2 from that right? Odd, I thought it'd be lower than that, doesn't seem like 2.0 ohms.

 

[ScorpioZZZ]

Cool, yes your math seems right. What gauge wire and how many wraps?

 

[asdaq]

To measure resistance it has to send some current to take an ohm reading, so it should have an internal 9v battery, there are two screws on the back.....

Sent from my Nexus 4 using Tapatalk 4 Beta

 

[zoiDman]

This one doesn't take a battery...

I think All Multi Meters need a Battery to Test Resistance.

I think the el-Cheap-o Centech DMM that Harbor Freight sells has a Non-Replaceable Battery.

 

[Zipslack]

Not all multimeters are created equal...some do a lousy job of reading low resistances, some don't do well with high resistances, etc. Try spending a little more to get a decent meter - the Craftsman stuff from Sears isn't bad ( and have excellent warranty), the RadioShack stuff is okay, even some of the units from HomeDepot. If you only spend $5-10, don't expect great results. However, for this kind of hobbyist work, I wouldn't recommend buying a Fluke or spending more than $30.

 

[NatureBoy]

Yeah, this is a cheapie.. doesn't have a user replaceable battery.

I have good quality meters back in Canada in storage, but I just didn't feel like spending money on one for only a couple purposes (checking batteries and resistance).

I'm using 32g kanthal, 4 wraps ATM.

 

[darkzero]

Yeah, this is a cheapie.. doesn't have a user replaceable battery.

Are you sure about that? Have you actually opened the case? Never heard of a disposable multimeter. Those cheap free with coupon MMs from HF have 9V batteries. Some MMs don't have a battery door, you have to unscrew the case to replace it. The Fluke I have at work doesn't have a battery door. I forget if my Fluke at home has a battery door but I use 4AA lithiums in it so it lasts a really long time.

 

[NatureBoy]

Are you sure about that? Have you actually opened the case? Never heard of a disposable multimeter. Those cheap free with coupon MMs from HF have 9V batteries. Some MMs don't have a battery door, you have to unscrew the case to replace it. The Fluke I have at work doesn't have a battery door. I forget if my Fluke at home has a battery door but I use 4AA lithiums in it so it lasts a really long time.

Yep, opened it up and almost broke it... it didn't want to open. No replaceable battery inside. I found it odd as well.

 

[Sonar505]

You must have gotten a weird batch. I just opened my free centech meter from harbor frieght. 2 screws on back inside a generic heavy duty 9 volt battery and replaceable fuse. back came off very easily you might have to remove the leads if yours are connected to back panel mine weren't. another thing to try is to remove leads and reseat even turn them a little while checking resistance of the leads this might steady out your reading if its still jumping.

 

[NatureBoy]

That's really weird. I wonder what's up with the one I have then... no 9v in there.

It seems to be giving me steady readings now.. takes a few seconds to settle on a number, but seems accurate.

 

[darkzero]

I too wonder what you got, maybe they changed them recently or you got something different. What sku is it? Disposable MM still does not make sense to me though.

I've had like ten of those free ones from HF in the past couple of years & they were all the same, had dry cell 9Vs in them. Dry cells don't last nearly as long or have as great of a shelf life than akalines so I wouldn't be surprised if some of them were low on battery. Can't say if I ever had your issue with one of them as I never used one & gave them all away. I have multimeters all over the house & with a couple of them I do get weird readings when the battery power is very low like the others have mentioned. But it does seem to only happen on the cheaper ones.

 

[BurntHit]

Not all multimeters are created equal...some do a lousy job of reading low resistances, some don't do well with high resistances, etc. Try spending a little more to get a decent meter - the Craftsman stuff from Sears isn't bad ( and have excellent warranty), the RadioShack stuff is okay, even some of the units from HomeDepot. If you only spend $5-10, don't expect great results. However, for this kind of hobbyist work, I wouldn't recommend buying a Fluke or spending more than $30.

I am going to agree and disagree…

I agree that not all DMMs are created equal… and you often get what you pay for.

Owning a quality multimeter is worth it, and not just for vaping. I get good use out of mine for many other thing. When it comes to tools in general, I try to buy decent stuff.

My Fluke 73III is still going strong and I’ve had it for years… Probably one of the best DMMs ive used at around $100 for the general hobbyist / home use. I also have a Fluke 87 V, cost substantially more, but again, worth it.
Fluke 73/77 Series III Digital Multimeter

If you just can’t afford it, you may want to look at this meter. Even I am tempted to buy one as a beater.
VC99 3.0" LCD Handheld Digital Multimeter (Voltage + Current + Resistance + Temperature/ 2*AAA) - Free Shipping - DealExtreme

You tube review:
EEVblog #91 - $50 Multimeter Shootout - Extech EX330, Amprobe AM220, Elenco, Vichy VC99, GS Pro-50 - YouTube