Coin cell not measuring voltage with multimeter

Hello,

I recently became interested in the Tiny AVR's and I have a coin cell (CR3032) project that powers a RF transmitter. The project works fine, placing LED's on the coin cell works fine, however I am not getting any measurements with my multimeter.

When I use the same multimeter in the same configuration I can measure 5v and 12v from other sources. I am simply holding the multimeter pins to the back (or side) and top of the coin cell.

On youtube I saw someone doing this with a coin cell without any issues. I'm really confused why the multimeter doesn't show anything. First I thought it was simply drained but I have new ones now and they show the same results.

I'm fairly sure this is an easy one. Got an idea?

I'm confused: your title talks of measuring current but the post says you measured 5V or 12V.... so which is it that you can't get from the cell, current or voltage?

If you're measuring current, you need to break the circuit with the meter.

If you connected the battery directly to the meter with the meter set to measure current, you may have blown the fuse in the meter. You’ll have to replace the fuse to get it to measure current again.
You should not measure current directly across a current source.

Pete

I agree, it's probably the fuse in the meter... A very common problem...

Usually, the current-fuse is replaceable so check the owner's manual for your meter. Or, just open it up and take a look.

The fuse is only used for current so you can pop it out (assuming it's user-replaceable) and check it's continuity (it should read around zero ohms). Don't try to measure the fuse without removing it because it's still connected to the multimeter circuitry and you could get an erroneous reading.

I don't know if a coin cell can put-out enough short-term current to blow a meter's fuse, but most batteries & power supplies can blow the fuse unless there is some current limiting in the circuit. It's also possible that the fuse was already blown.

In the current mode the meter "shorts-out" the circuit so you should never connect it directly across a battery or power supply in the current-mode.

My bad, I am trying to measure voltage, not current. Thanks. However when I use the voltage setting I do get 5v and 12v but nothing from the coin cell.

Does the voltage also have a fuse that could be blown? How can it measure 5v and 12v but not 3.3v?

First of all, try wiping the coin cell with alcohol. It's not at all uncommon for them to have some sort of film on them right out of the package.

Nevermind. I tried again and the multimeter doesn't seem to measure anything anymore. It might have been in the process of dying or something because it's dead now.

Fexduino:
because it's dead now.

Well if it's a digital meter, perhaps it just needs a new battery?

Dead as in nothing, or dead as in shows a lot of zeros?

It shows zeros :slight_smile: but yeah I’ll try a new 9v battery first. Thanks so far …

Check your leads for breaks too. If you've got a good pair of silicone insulated test leads, sometimes it's hard to notice that one of the banana plugs is no longer attached to the actual cable. God knows I've tried that a few times.

Hi,
Check as suggested before, if the DMM has a fuse, usually located in the battery area, see if it has blown.

Tom.... :slight_smile:

Allright, I’m back with a new 9v battery. All works well not, except those coin cells. When I measure them on the voltage setting always get an instant -1. I’ve also tried AA batteries, same result. What am I doing wrong?

Set the meter to ohms reading and short the probes. What does it read on the display?

// Per.

-1 suggests overload, you're not trying to read 3V on a 2V range?

BTW those cells are extremely weak and are usually rated for up to 2mA load only.