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Pat King
question about battery life
on Aug 19, 2005 at 4:47:36 am

the 9V and 1.5V(AA) batteries I use in mics and wireless units.

If I put a volt meter on a battery and it reads close to the stated voltage does that mean the battery is OK? Does a battery just lose voltage as it dies? At what discharge percentage should a battery be discarded?

Can anyone recommend a good brand/model number for rechargeable batteries?


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Matte
Re: question about battery life
on Aug 19, 2005 at 1:07:20 pm

[Pat King] "Does a battery just lose voltage as it dies?"

The "voltage" is the last thing to go (on the meter) so that's not a good way to check any battery.

Current (Amps) under LOAD is what equates to battery "power".

There's a quick way you can test any small battery using an inexpensive multi-meter.
The meter needs to have a "DC Amps" (or DCA) setting that is at least capable of 5 amps or more (usually they are 10A or 20 A).
This Amp reading usually has a separate CONNECTION (only for the AMPS reading) for the red probe on the front of the meter.

Connect the probes, and observe the polarity on the battery.

CAUTION:
Make these readings very SHORT (about 3-5 seconds is max.) as the meter will put a virtual SHORT across the battery while it is connected. This simulates a full LOAD across the battery which makes the reading very accurate to actual battery condition.

For 1.5v Alkaline batteries a "good" reading should be 3 to 4.5 A. (The higher, the better.)
For 9v Alkaline batteries a "good" reading should be 4 to 5.5 A. (The higher, the better.)

For standard lead-acid (ironically called "heavy duty" by most manufacturers) batteries the readings
will be about an amp LOWER (2.5 to 4.5) and still indicate a "good" battery.

Again, don't let the meter stay across the battery but a very few seconds so you don't overheat (and run down) the battery.


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Matte
Re: question about battery life
on Aug 19, 2005 at 1:22:05 pm

I re-read my post (shoulda done that before I sent it, huh?) and I should have said "zinc chloride" instead of " lead-acid" in describing so-called "Heavy Duty" standard batteries.

Also, for RECHARGEABLE batteries (all depending on the composition) the Amp readings should be very close to that of the good Alkaline batteries.

To find out for sure what a "good" battery should read on the meter with YOUR brand/kind of rechargables:
Fully charge one of your (known-to-be-good) batteries and put it briefly on your meter.
Whatever it reads, you can use that as the relative "benchmark" for that kind of battery.


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Peter Perry
Re: question about battery life
on Aug 19, 2005 at 9:39:43 pm

I have never had good luck with rechargeable batteries. Regular batteries slowly give up the ghost and the equipment seems to be able to tolerate that......rechargeables work/then don't. Real quickly.
I have been working in theater and TV sound for over 20 years in Boston and NYC and no one, and I mean NO ONE, uses rechargeables. And when I think of some of the nickel squeezing places I have worked, that's saying something.
Peter


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Tom
Re: question about battery life
by
on Aug 20, 2005 at 1:07:29 pm

The small cost of batteries is worth it. When wiring the cast for a live theatre performance that sometimes uses 25+ wireless beltpack transmitters. Before each show each one gets a new battery AND after the show they are left on intentionaly to go completely dead. That way they is never any doubt if the battery is new or old , good or bad.

Tom :)


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