Help with testing my mAh

[broccoli and steam]

Hi - I've been a member for a while, almost 2 months now, tried to post 5 to 7 times, can't seem to find just the regular "post new thread" area - and I'm still on the new members forum with this. When I hit "What's new" and hit "my posts" it always takes me to a visitor area, I post as a visitor and nothing seems to happen, no one sees it I don't believe but not sure - can any one help with this? Anytime - down the road - no rush/no urgency.

Please however, If anyone help me figure out how to test the mAh on some specific batteries, it would be greatly appreciated! I've got a multimeter that I bought (had mailed) from a local vapor hobby shop (KZOO Michigan - awesome place if anyone's in Michigan) but it didn't come with any instructions.) I'll do a few work things then come back and try to post and take a picture of the multimeter, but I watched the guy test several of my eGo and other batteries while in the shop. He was able to do it right away with no problems - same exact multimeter. So I know this multimeter can do it. I just need to know what to set it to and how to place the red and black testers - it's just a regular multimeter I believe. If anyone's awake and around please help!! Thanks in advance.

 

[dormouse]

No idea how you could possibly test it. The only guideline is 100mah is about 1 hour of moderate vaping with a standard resistance atomizer or cartomizer.

if you have a specific model like Ego or any model, post the model name (and threading type if you know) and length and diameter of the battery (length is enough for slim models, diameter and length for fat battery models) and somebody will probably know.

And if you have a slim ecig you should not use low resistance atomizers and cartomizers - they can damage slim batteries. ALL 450mah+ batteries are fat models like Ego or mods w/ removable industrial batteries (1 or more) and those are the ones low resistance attachments can be used with.

re measuring - I am only guessing, but I imagine the battery manufactures can put the bare battery (not inside an ecig) on some kind of rig and draw a specific amount of current out of it constantly over time and calculate the mah of the battery?

Here is some actual info
http://www.reuk.co.uk/Measuring-the-Capacity-of-a-Battery.htm

 

[madpinger]

That's a pretty good link dormouse, I was going to just post google OHMS law, etc. That's a much better answer tho.

For practical terms tho. Just make a habit of doing 5 second draws for low resistance or button presses and keep track.
Thing is, the capacity will reduce over each charge of the battery. You'll get the basic idea of what to expect after a while either way tho.

I had a 450mah battery on my first kit and by the time I had charged it a few times, it needed charged twice a day.
I'm on a 1100mah battery now. While larger, I don't worry about running out of battery power when out and about.

 

[Icoth]

He probably tested the voltage, not the mAh. Here's a link on some simple and useful tests:
Using Your Multimeter - Cloud 9 Vaping

 

[broccoli and steam]

Thanks for sure. Both links were great. I guess everyone agrees one can't simply test battery mAh from a multimeter. The store there in KZOO is still great but I swear I "saws what I saws," he tested mAh on one of my old eGo 900 batteries with this thing.

BTW, Icoth's multimeter is the exact one I'm using. When I followed the instructions, 4 different carto's from 3 different sources all read .3 to .5 higher than what was advertized. Is this common?

 

[madjack]

4 different carto's from 3 different sources all read .3 to .5 higher than what was advertized. Is this common?

...not uncommon...also consider, this discrepancy could be within the +- accuracy tolerances of the meter itself......
madjack

 

[AttyPops]

IDK if it was in the links above... but you have to subtract the meter's resistance when measuring ohms, like madjack is saying... there is a tollerance. Most resistors are measured in 10's of ohms at minimum often 1000's or millions of ohms... so multi-meters often don't do well with 1.5 ohms and such.

Touch the probes together and see if they read anything other than zero. Subtract that from the ohm reading of the atty/carto.

mAh is a battery capacity rating (like how full is the gas tank in a car?) not a voltage or an amperage at-the-moment test.

He may have tested voltage (pressure in the fuel line at any one point in time). He may have tested amperage (mA) (flow rate in the gas line at any one point in time) but he didn't test mAh (how much gas is in the tank) with a multi-meter that I know of.

 

[Icoth]

I guess everyone agrees one can't simply test battery mAh from a multimeter. The store there in KZOO is still great but I swear I "saws what I saws," he tested mAh on one of my old eGo 900 batteries with this thing.

Well I guess you have to go back to the store and ask about it. If there's a simple way to test mAh I'd love to hear about it, and besides, never waste an excuse to buy more vaping gear

As far as the carto resistance, a .5 ohm difference sounds pretty high, probably caused by all the factors already mentioned. What you're really checking for though are DOAs, extremely high or low resistance. Vendor warranties can't really be too long, so this check can save you some money. Best to do this test before use. Filling with liquid and vape time also change the resistance.

 

[rwnielsen]

When I followed the instructions, 4 different carto's from 3 different sources all read .3 to .5 higher than what was advertized. Is this common?

A good quality ohm meter will measure the resistance in it's own test leads

 

[madjack]

A good quality ohm meter will measure the resistance in it's own test leads

...yep, that is one reason you havvta 0 out any ohm meter before use...also, as stated above, once a carto has been filled and used, an accurate measurement can't be made in regards to what ohms it started with.....
madjack

 

[Uncle Sam]

There is no way to test the mAh on a battery without load testing it, which is connecting it to a known load (resistance value) and running it until exhausted.

mAh = milli amp hours.

For example, an average car battery is rated 650 amp hours. That means you can draw 7800 watts (Amp x Voltage) for ONE hour before the battery is spent. Or you could draw one amp (12 watts) for 650 hours.

the millamp rating is a function of the resistance of the atomizer divided from the voltage of the battery.

 

[aerosol77]

There is no way to test the mAh on a battery without load testing it, which is connecting it to a known load (resistance value) and running it until exhausted.

mAh = milli amp hours.

For example, an average car battery is rated 650 amp hours. That means you can draw 7800 watts (Amp x Voltage) for ONE hour before the battery is spent. Or you could draw one amp (12 watts) for 650 hours.

the millamp rating is a function of the resistance of the atomizer divided from the voltage of the battery.

Technically, one can check battery capacity without running it all the way down, but one needs to have the specific batteries characteristics fully modeled. BY specific, I'm referring to exactly the same battery, exactly the same design, and in some cases, exactly the same manufacturing lot. Typical LiIon batteries are often private labeled, more often than not on a whim, and a generic model wont work, and if a private labeler changes vendors, a known good model could fail in an instant.

The way this works, is that a batteries impedance changes as a function of capacity and with a previously modeled battery, the prediction can be pretty decent. The problem is the test gear to do such is not simple, nor inexpensive, and accurate models of specific batteries are tightly held IP, so substantial reverse engineering is needed to create them in the charger/test device. This pretty much means its unlikely we will see a generic 18650 capacity tester, where as such testers are quite common in the automotive realm, albeit spendy, as the lead acid models are more tolerant of design differences.