I bought a radio shack multitester to check my batteries, primarily my
laptop batteries. First on my old dead battery of Toshiba laptop, they
had a positive and negative mark shown..so it was easy to check it out
with the tester. But I bought it to check my Dell battery that lasted 1
year to the day of the end of my warranty. Fortunately, i did get a
refurbished one in time. Disappointed that it only lasted a year and I
had only used it a total of maybe 10 hours with the battery on my last
vacation...10 hours in 1 year and poof it went. The battery does not
have a pos and neg shown like the toshiba one..so I cannot test it that
way. In the meantime, I was trying to check some AA and AAA batteries
that I had and was able to understand on how to test them..but I do not
know how to interpret the readings I used the ACV side with it set at
15. I really don't know what does numbers mean. The manual is a joke,
at least for those of us that have no experience. The line moved a
little to the right where it seem to end a couple of notches on that ac
15v scale. It read the same for the new battery as well, so what is it
telling me that its a 1.5v battery? How does one know if the battery is
weak or whatever? Does anyone know of a web site that can tell me what
those readings represent? I did a search in google but nothing came to
what I was hoping for.
You have the meter set on AC. Batteries are DC, so you want it set on
one of the DC ranges. Sounds like you have an analog meter, in which
case you need the polarity correct for the meter to move to the right.
With the digital meters I have seen, polarity doesn't matter. If you
have it reversed, the voltage will just read with a minus sign in
If the battery is new it should read 1.5V.
All batteries are DC so you need a DCV range. With a digital meter it
doesn't matter which is positive and negative as it will simply show the
correct voltage with a - sign if you have it backwards. With an analog
meter the needle will go backwards to the stop and you just have to
reverse the leads. The meter will be of limited use for rechargeable
batteries like a laptop one since it only tells you the voltage, not the
state of charge.
batteries may be DC but some chargers give out AC, it allow the use to
connect the batterie pack to the charger wihout any care for polarity
the battery pack contain diode that correct the AC to DC, that could
explain why there arent any polarity sign.. but beware laptop aren't my
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Tool manuals are not intended to provide lessons,
in your case, on electricity. You need a simple
book that includes basic discussions and standard
abbreviations. That is where you start, not with
the multimeter. For example, ACV means
alternating current voltage. Batteries don't use
AC they use DC (direct current) so your meter
should be set on DCV. Further you need to read
some about batteries and there are excellent
sources online so just look at google results for
"batteries." Standard (alkaline) nonchargeable AA
and AAA cells read about 1.6 volts when new and
about 1.3 when discharged to a level they won't
work in most equipment.
Alkaline, NiMH, and Li-Ion (your laptop) batteries
have different characteristics that you need to
read about before you can analyze the voltage
I know you said multitester, but since you mentioned that you are using
the AC scale, can I safely assume you mean a multimeter?
Multimeters are not always the best device for testing batteries. Yes
they will indeed tell you when a battery is just about dead, but they
can be misleading when a battery is weak.
Most multi-meters don't put enough of a load on battery when they are
being tested, so they may read the full voltage when bench tested, but
once the batery is put back in the device, they may not be strong
enough to power said device.
When testing a battery with a multimeter, it should be tested under
Possibly, but I always had my ac adapter connected to it, so I assumed
that it was constantly being recharged. If lack of battery usage...what
is considered normal usage, so I won't lose my refurbished one the same
As others have already said, you need to use the DC scale.
You need to do some reading about how battery voltages change with state
of charge. Lots of those type sites on the web. Something like this
one that I found with a quick look:
Your Dell battery is a set of several hooked in series. The voltage
will be approximately 1.2 times the number of batteries. For example a
15 cell NICAD battery will measure about 18 volts (1.2 x 15). If it
suddenly drops by about 1.2 volts it means that one of the cells has
That's why I don't like things that run on batteries. I'm 59 and when
I grew up, anything other than a flashlight that required batteries
was a luxury. I still feel that way, although I have a few more
things than I used to that use batteries.
One of the purposes of the meter is to identify + and -. Hold it on
one and tap it on the other to see whih way the needle moves. If it
moves to the left, reverse the leads.
We went over this in high school chemistry (which was almost as high
level as my college chem oourse) and I'm sad to say that I can't
reproduce the numbers, but I saw them and they made sense. That is, g
the arithmetic shows that it's the nature of chemical reactions that
the voltage stays rather high until the battery is almost fully
discharged. So even moderate decreases in voltage represent major
loss of charge in most cases. They are right that different kinds of
batteries are different in details, but all share this. For a
flashlight battery it has to be 80% discharged before the voltage
drops to 80% of original. Or maybe 90% and 90%. But like someone
said, the voltage might be 90%, but it doesn't have the capacity to
put out the amount of current you still need.
When you have doubts if it is the battery or the device, try a good
battery and see if it works better.
I am surprised nobody else mentioned this but you should also choose a
scale on the meter that will get your reading about center of the
scale. i.e. if you where testing a battery where you expected about 1.2
volts you should be using a scale that is about 0-2.5 volts. Analog
meters are most accurate in the center of the scale.
Buy a $3 digital tester from Harbor Freight and
you won't need to worry about being in the middle
of the scale and you won't need to worry about
polarity (it will tell you). The lowest scale on
many testers is in the 20-25V range anyway.
On the guys main problem, notebook batteries, I went through a couple
batteries on my Gateway, which is now about 6 years old. The original
battery lasted about 2 years. That one I had always left in the PC,
so it was mostly constantly charged, with occasional use disconnected.
The next battery was an aftermarket one I bought on Ebay. That one
lasted about a year.
Then I started to realize that for 99% of how I used the notebook, I
didn't need the battery. I pretty much used it at home or when away at
a hotel or similar place that had AC. It was rare that I really needed
or wanted to use it on a plane, car, etc.
So, I concluded for my usage model, the simplest thing was to remove
the battery. It not only solved the problem, but made the notebook
considerably lighter as well. Not suggesting that's what everyone
should do, but if it fits your usage model, it is an option.
As for Gateway, I'd never buy a system from them again. My system
came with Windows ME. Less than a year later MSFT was shipping XP,
which the system was clearly capable or running, but because of driver
issues, I can't install it on mine and Gateway refused to provide
updated drivers for a year old system. The final insult was while I
was logged into their website looking for drivers, a scum bag calls up
trying to sell me memory, which I didn't need and explaining how XP is
a whole new system, and it's all MSFT fault that I can't put it on my
PC. Funny thing that I upgraded and put it on another PC that was a
no-name I had put together about the same time off a website by
checking MB from X, Disk from Y, Display Adaptor from Z, etc.
Seemed pretty obvious to me Gateway tracks users by identifying their
PC's from service info and when they log in looking for support,
instead of providing a driver, they hit them up for more sales.
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