how to test batteries???

[djenkins]

sorry this is probably a dumb question but can you test batteries with a multi-meter or do you have to have a battery tester?? i have a multi-meter with a battery function, but i dont know what is good, bad or ok?? on a battery i know is good it reads like 4.2ma so i guess that is good, but what would a dead battery read, or a weak one??:thinking:

Just looking for a way to test the batteries till i can get my maha 808m

 

[Lumencraft (Matt)]

nvm


Not a dumb question though.

 

[LuxLuthor]

You can accurately test Lithium Ion batteries with a DMM, measuring the voltage. However, it is best to use a battery tester that applies a load to the cell for Lithium Primary, NiMH, & alkaline. For example the ZTS tester.

 

[kurni]

You can accurately test Lithium Ion batteries with a DMM, measuring the voltage. However, it is best to use a battery tester that applies a load to the cell for Lithium Primary, NiMH, & alkaline. For example the ZTS tester.

Oh, so voltage is not the only measure. That makes perfect sense, thx LL, I always wondered about this.

Kind regards,
Kurni

 

[JB01245]

I bought this tester in hopes of it helping to identify a bad battery pack (7.4V Li-Ion) without having to run and monitor it for running for 3hrs - http://www.rc-cars-planes.com/wattmeter-simulator.html

Pretty neat little meter. The only "bad battery" clue I have noticed is the voltage dropping faster with a load (my light) on a bad pack versus a good pack. Other things noticed - pack charges a lot faster than normal and doesn't get to the peak 8.4v charged state when the charger light turns green.

Can anyone point me to some identifyers for a bad Li-Ion 7.4V Li-Ion battery pack with protection circuit beside running it?

 

[LuxLuthor]

I bought this tester in hopes of it helping to identify a bad battery pack (7.4V Li-Ion) without having to run and monitor it for running for 3hrs - http://www.rc-cars-planes.com/wattmeter-simulator.html

Pretty neat little meter. The only "bad battery" clue I have noticed is the voltage dropping faster with a load (my light) on a bad pack versus a good pack. Other things noticed - pack charges a lot faster than normal and doesn't get to the peak 8.4v charged state when the charger light turns green.

Can anyone point me to some identifyers for a bad Li-Ion 7.4V Li-Ion battery pack with protection circuit beside running it?

The main thing is to measure the voltage of individual cells. Both should charge up to 4.2V and be at similar voltages when discharged down to about 3.5V each. You can discharge Li-Ion cells lower, but very little charge capacity is left below that, and you run a risk of reducing the cell's life and performance by pushing it lower.

On a practical basis, since all Li-Ion's degrade their life/performance over several years and/or charge cycles, you will begin to notice decreasing run time, and voltage dropping faster than when new. Much of this information is on various pages at Battery University here.