Why use an actual coil ohm reader when I have a multimeter?

[siraig]

Question should be fairly self explanatory... I have done quite a few electronics testing, etc during my career as a motorcycle technician. I am well aware how to test for resistances and how to use a multimeter. I cannot think of a reason why I would need to buy a dedicated ohm meter for measure assembled atomizers whenever I can accomplish the same task with a multimeter.

Someone please correct me if my thinking here is flawed, just trying to cover all of the bases before I get ready to build my own.

 

[State O' Flux]

No problems using a DMM... until you get down to deep sub-ohm values. If you're build is 0.5Ω or 0.55Ω... it's not such a big deal, as current draw is modest. If, on the other hand, your build is 0.1Ω or 0.15Ω... it can rapidly become a big deal.

At this point, not only resolution & a solid connection can make quite a difference... but accuracy becomes paramount.

Odd thing is though... most of the Chinese dedicated Ohm meter/build boxes have milliohm resolution... but few have sufficient accuracy to provide a reading you can trust to be accurate.

I've found that the meters with the most consistent accuracy (0.020Ω or less) are available from "USA Ohm Meters". Pricing is a bit more than the usual crap... but they're a US company with a proprietary (but still Chinese) chip, quality enclosures & component parts... and first class customer service.

Of course, IMO if your builds are above 0.25Ω or so, you really don't need a dedicated box... if you already have a good DMM you trust and are familiar with it's included resistance, if any.

 

[graffiti]

If you have a multimeter that accurately does resistance to the hundredths down to around 0.05Ω (for safety) I don't see why you would need a dedicated resistance meter.

 

[W00fy]

I like the fact that I can screw the atty into the resistance meter - it's like a firm, stable base to work on. Plus holding DMM probes into the atty bottom-connector is a little tricky - As State O' Flux says, measuring sub-ohm can be difficult, and holding DMM probes in place long enough to get an accurate reading can be tough.

 

[Frenchfry1942]

I have one and I use it, also, as a building stand. I didn't have a multi-meter...that I knew about. Anyway, I build on it and test there and then take it off and put it on a mod. There, I check it again and then squeeze the coil and test again. Just routine and safe.

Their are many routines, just works.

 

[Unforeseen]

You are correct in that you do not need a dedicated ohm meter. They are not as accurate as a multimeter.

Since you already have one. It will do a perfect job in testing either the resistance on your atomizer or the voltage of your battery.

 

[pdib]

No problems using a DMM... until you get down to deep sub-ohm values. If you're build is 0.5Ω or 0.55Ω... it's not such a big deal, as current draw is modest. If, on the other hand, your build is 0.1Ω or 0.15Ω... it can rapidly become a big deal.

At this point, not only resolution & a solid connection can make quite a difference... but accuracy becomes paramount.

Odd thing is though... most of the Chinese dedicated Ohm meter/build boxes have milliohm resolution... but few have sufficient accuracy to provide a reading you can trust to be accurate.

I've found that the meters with the most consistent accuracy (0.020Ω or less) are available from "USA Ohm Meters". Pricing is a bit more than the usual crap... but they're a US company with a proprietary (but still Chinese) chip, quality enclosures & component parts... and first class customer service.

Of course, IMO if your builds are above 0.25Ω or so, you really don't need a dedicated box... if you already have a good DMM you trust and are familiar with it's included resistance, if any.

this ↑ exactly. (including the USA Ohmmeter recommendation)

One thing I would add is that the DMM will allow you to check resistance with the atty screwed onto the mod. Many hard shorts occur in the 510 connection (I would venture to say "most"). It's all good and fine to check the resistance of your coil(s); but if you check before you attach your atty to the mod, you haven't really tested the whole circuit. In fact, you haven't tested the most (or maybe 2nd most) pernicious part of it.

Both my DMMs were off by about 0.1Ω. (Klein MM200 & Sperry DM-6450) But that was fine until I got down to .3Ω and below, since the IMR batteries I use are rated at 20A continuous.

 

[Rickajho]

If you are using a decent quality DMM you are fine. The problem is there are a lot of cheap crap meters out there that don't do a good job measuring resistance in the very low range we use. Junk meters can be off as much as +4.0 ohms when trying to measure a 1.0 ohm coil. Just for giggles I keep trying out those "free with coupon" meters you can get at Harbor Freight - because they are free - and not one of them is correct at reading low ohms. They are fine for measuring DC battery voltage but don't expect a cheap meter to give you anything close to a correct reading with it comes to resistance below... about 100 ohms.

Having said that the dedicated ohm checkers vary in quality quite a lot as well. If you expect to get a good one on eBay for six bucks fagettaboutit. The only one I like the specs on is sold by nhaler and having one it seems to be fairly accurate against my bench meter. It also costs a lot more than a lot of people want to pay at $22.00.

Udder than the accuracy issue, a lot of people like the dedicated checkers because it provides a stable platform to build on.

 

[classwife]

moved to Batteries and Chargers from Rebuildable Atomizer Systems

Forum: Batteries and Chargers
Discussion of batteries, chargers and multimeters used in association with APVs.

 

[Slurp812]

I have a cheap DMM. And cheap leads. Likely they are .1 ohms themselves. So I cant accurately measure low sub ohm coils with it. If I got some better (thicker wire) leads, it would be much more accurate....