How to test battery cells

[ironsniper1]

I know there are electronics people here can some one tell me what I should set my meter too, to test a battery cell from a laptop battery I took apart? I just need to see how many are bad

[RED333]

If they are lithium ion, DO NOT MESS WITH THEM!

Ni Cad, be careful.

Take the pack to Batters Plus, they will have a replacement or repair.

On the meter, look for "V" with a straight line above or below the V.

[Dustbuster]

batteries for laptops especially todays batteries are lithium ion or lithium polymer and are very volatile,dangerous,can explode, and should not be load tested.what you spend on a new battery is a lot less than the deductible on your health insurance........ your meter is set to test a diode, not a battery based on the photo you attached.

Not trying to be a dick but like red indicated, seek out batteries plus or go online and find a replacement.If this is part of a study and youre trying to learn, radio shack has some excellent books on basic dc electronics that are cheap and easy to understand.

hope this helps

[ironsniper1]

I'm not worried about anything bad happening I have been shocked and have stuff short out in my face also batteries plus prices are outrageous I got a battery from them once it lasted a month

[RED333]

We tried.

[ironsniper1]

hey you only live once:) anyway i got it figured out and out of the 6 cells 4 are bad so im going to order 6 new ones and get to soldering!

[10-Ring]

I'm not worried about anything bad happening I have been shocked and have stuff short out in my face also batteries plus prices are outrageous I got a battery from them once it lasted a month

I've bought 3 batteries from Batteries Plus in the past year or so.  All 3 motorcycle batteries.  One is a higher end battery and has been fine, the other two suck.  One was bought in April and replaced under warranty in July, I rode that bike the othe day and the battery sounded a little weak.  The other motorcycle battery I bought in May, took it back in August, they said that it was fine, yet it will not start the mower.  I'm done with that place, except to continue to return my crappy batteries when they get a dead cell every 3 months. 

[jcj]

I'm not worried about anything bad happening I have been shocked and have stuff short out in my face also batteries plus prices are outrageous I got a battery from them once it lasted a month

Fair enough. But you should know that LION cells don't just "short out" or shock you. They simply blow up like nice little sticks of dynamite. Quite capable of doing some serious damage to everything around them.

[tnguy]

Here's the thing, you can measure the voltage of a cell which may give you some indication but the problem is that certain types of cell will maintain a fairly constant voltage throughout their life. What you have to do is measure the voltage with an applied load. I have a multimeter with a battery test setting for 9V and 1.5V. It applies a 100Ohm load to the battery and measures the voltage, displaying it on a simple good/bad scale. This is meant for regular batteries however. LiIon batteries can supply a lot more current so 100Ohms may be too small.


 

[tnguy]

Having attempted and failed to replace the cells in a laptop battery, I have to say that it was such a PITA that you're probably better off just buying a replacement off ebay. If you don't mind taking your chances (I've had mixed success), you can buy a no-name for pretty cheap.

 

The deal is that the metal connectors are welded on, not soldered. The cells are next to impossible to solder. After I managed to get all the old cells disconnected and the new ones in place, I put the pack back in the laptop and it refused to recognize it. I found a new OEM on ebay for $18.

Edited November 11, 2013 by tnguy

[McGarrett]

If they are lithium ion, DO NOT MESS WITH THEM!

Ni Cad, be careful.

Take the pack to Batters Plus, they will have a replacement or repair.

On the meter, look for "V" with a straight line above or below the V.

Listen to Red, not worth the risk, just replace! Boom!

 

V with wavy line=AC volts, V with straight or dash line=DC volts

 

There is much more to testing a battery accurately than measuring the surface charge with a voltmeter. 

[Guest Lester Weevils]

In addition to blowing up, you can get a hot lithium fire that you can't put out til it burns out on its own. Will burn thru your workbench then try to burn thru your floor, and if the floor ain't concrete then the lithium fire will probably suceed. Edited November 12, 2013 by Lester Weevils

[TripleDigitRide]

I know someone who had to undergo multiple surgeries on both hands from an exploding Li-Ion battery for a R/C airplane. This was after one caught fire while on the charger in his garage.

[Guest Lester Weevils]

The better individual lithium cells have protection in each cell, which can sometimes avoid tragedy, though there are plenty of unprotected cells as well.

Haven't been inside a laptop battery pack lately, but in the past they would have an external to the batteries protection circuit inside the pack.

About a year ago the macbook, one day the batt was fine, next day it was dead. So I pulled the batt pack and noticed it was all swollen up and the plastic was a little discolored. So am guessing the protection circuit did its job, no explosion or fire. The batt lasted about 4 years, and a new batt worked just fine. Edited November 12, 2013 by Lester Weevils