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Why shouldn't I use the 10A reading in a multimeter to test for battery life?
I would like to use a multimeter to test the residual charge of some batteries I have. Every tutorial I find on the net, after pointing out that you really should use a battery tester because it applies a constant load on the battery, says that you can use a multimeter anyways. The method would be to set it to VDC readings, and test the V output of the battery. Then of course, they warn you that the V output only decreases much when a battery is really, really worn out.
But I don't understand why I shouldn't use the multimeter in 10A reading. If I do it, I can quickly spot a charged battery (reads about 2.2A) from a spent battery (reads 1A or even .25A).
Why shouldn't I? I really don't mind spending a bit of the remaining charge to test it, it's just a couple of seconds on the meter...
Thanks for your reply Melodi.
Let me add that I'm only testing 1.5V AA or AAA batteries, so it's not a big load that goes through. I won't be doing this on my car battery, no-no, sulphuric acid hurts :)
6 Answers
- ?Lv 51 decade agoFavorite Answer
Probably ok on a small battery that has a fairly high internal resistance.
Try it on a 12v lead acid battery and you will instantly block the fuse in the multimeter.
- Albert WLv 71 decade ago
Hi There,
The amp setting will put a direct short on your batteries and really can not tell you the amount of charge they had before you shorted them out. Not the way to test them.
The voltage reading is the best way to test.
A fully charged AA orAAA battery will read 1.5 volts at best (for a carbon zinc cell). NiCad cells will measure about 1.24 volts. Lithium Ion cells will measure about 1.3 volts.
You can get a new cell and test then compare the readings.
Hope this helps,
Al
- Frank KLv 41 decade ago
Amperage is the amount of power the unit is drawing from the source (ie; your batteries)
Therefore the multimeter would have to be used in a in-line method. For example:
battery>>>>>multimeter>>>>>fixture(ie; light)
More is required, but this would give you a general ideal of how the amp is measured.
- 1 decade ago
Why would you want to test any battery using amperage? You are putting an unnecessary load on it, and wasting it at the same time. Using a meter to measure the voltage is the best way to truly test it. If it is at or near the output voltage it is good, and half to nothing it's bad. Simple as that. Don't make it difficult.
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