Battery Noob: How do you check the voltage with a multimeter?

[Delta]

I see where most of you are checking the voltage of batteries as they are charging to get it just right. Having no electrical experience, can you explain in simple terms how you are checking the voltage with a Multi-meter, and what am I looking for in a meter if I go get one?

 

[DM51]

Very simple. Select the appropriate DC volts range on the dial, then put the red probe on the +ve terminal of the cell and the black one on the -ve. If you put them the wrong way round it won't kill the meter, it will just read the voltage with a minus in front of it.

It would probably be a good idea to go to a small hardware/electrical store to get some advice, and see which meter suits you. Get a digital one that is accurate to 0.01 volts (get the guy in the store to demonstrate its accuracy, comparing it against an expensive one like a Fluke).

 

[gswitter]

This tutorial covers it.

 

[RGB_LED]

Great information gswitter - exactly the information that I was also looking for.:thumbsup:

 

[aim54x]

I went looking for this tutorial but the link was dead....turns out it has a new home

http://www.ladyada.net/library/metertut/voltage.html

 

[TooManyGizmos]

There is also this CPF thread ... w 90 posts.

 

[hazna]

There is also this CPF thread ... w 90 posts.

+1 great thread

 

[amsgator]

That thread is way too complicated for my little brain.

I ordered some 18650s today, when they get here, what do I need to do to check their voltage? Just connect the positive and negative terminals to the battery, or is there something special that needs to be done? That tutorial gets very confusing, when all I want to do is make sure the batteries dont get over 4.1 volts while charging.

Is it possible to rest the probes on the battery while it charges and watch it gradually go up, or do I have to pull the battery off while testing?

 

[Bullzeyebill]

That tutorial link is about as simple as it gets, and with pictures too. Are you using a DMM? Please go back and study that tutorial closely, and I think that you will figure it out. Checking the voltage of Lithium Ion cells is dear to our hearts here on CPF, and we want you to do it right. There are examples of testing the voltage and current of charging cells in that link.

Bill

 

[amsgator]

That tutorial link is about as simple as it gets, and with pictures too. Are you using a DMM? Please go back and study that tutorial closely, and I think that you will figure it out. Checking the voltage of Lithium Ion cells is dear to our hearts here on CPF, and we want you to do it right. There are examples of testing the voltage and current of charging cells in that link.

Bill

I've read on cpf it's as simple as touching the probes to the battery terminals and then that tutorial goes into using a resistor etc. So I'm confused on what to do. All I want to do is measure the voltage to keep it under 4.2v off the charger

 

[Bullzeyebill]

Read back in this thread to what DM51 says. He says it simple.

Bill

 

[gcbryan]

I've read on cpf it's as simple as touching the probes to the battery terminals and then that tutorial goes into using a resistor etc. So I'm confused on what to do. All I want to do is measure the voltage to keep it under 4.2v off the charger

Get a charger that limits it to 4.2V. Then after it's through charging turn the multi-meter to DC V set the dial to whatever is close (20V) and touch the probes to the + and - of the battery.

If you find that the charger is overcharging then get a new charger. I don't know about you but I'm not going to stand over a charger for several hours checking the voltage while it's charging.

This may not be the correct way to do it but it's what I do.

 

[amsgator]

Sounds good. The ones I ordered supposedly shut off when the battery is charged, but we'll see. It will be a while before anything gets here I'm sure since DX takes a while.