Some wireless mic systems don't perform well once the battery
voltage drops below about 8 volts. We were curious to hear what
kind of battery those in the group are using, and how long they
go before changing to a new one. Here's what we found.
From: Curt Taipale (Taipale Media Systems, Inc.)
Subject: Re: batteries
Hi y'all!
By the way, since our solution of the hearing assistance
system and lapel
mics ended up using lots of batteries, I'm curious to hear what
y'all are
using for batteries.
We depended on Duracell 9 Volt batteries. For every service,
each wireless
lapel transmitter and handheld wireless transmitter would be fitted
with a
fresh (voltage-confirmed) battery. The same went for the hearing
assistance
receivers (though I don't recall what kind of battery they used).
We tried to switch to some true 9V rechargeables at one
time, but even with
all of our support we never came up with a dependable system to
be sure they
were recharged properly.
Which brings up another point - if you're using rechargeable
9V batteries,
check the fine print. Most of the so-called "9V" rechargeable
batteries are
actually only about 7.6 volts on a full charge. Through testing
we
determined that it wasn't safe to send a transmitter out on stage
with less
than about 8 volts. I've seen only a couple of manufacturers who
produce a
"9V" battery that will give you something on the order
of 8.5 volts. I found
the others weren't worth bothering with.
Also, when the alkaline batteries would go, they'd give
you some warning by
dying slowly - which gave us some time to plan a swap for a replacement
mic
or battery. When the rechargeables lost their charge, they went
in a hurry -
with hardly enough time to run toward the stage.
As much as we want to save the money, we decided long ago
that our pastor was
worth the $1.50 per service for a fresh 9V Duracell.
Fire at will!
Curt Taipale
curt@churchsoundcheck.com
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From: Andrew Smithies (Wellington, New Zealand)
Subject: Re: batteries
My brother has built a battery cycling/charger for his
church. After each
service all nicads are dumped into a unit that first runs them
flat and
then recharges them ready for their next use. The next step in
its
development is to do this twice and measure and record the first
and second
discharge energies. That way the health of the battery and the
percentage
used and end of service can be determined. If a battery has a
capacity that
is reducing to a low point AND it is nearly flat after use it
is then
replaced.
This auto cycle system also looks after the cells ensuring
the memory
effect is keep at bay and so the cells last for ages. Time delay
start etc
is also useful so that the nicad spends most of its shelf time
flat rather
than charged. (This reduces the dendrite growths inside the battery
which
leads to high self discharge!)
My brother has had good success with his unit. What would
be good is to
build a version using a HC05 microcontroller (or the like). Then
a dozen
batteries could easily be handled at once and a PC or terminal
could be
plugged into a serial port to get the details. There are also
some dinky
display units around that are quite cheap instead of the PC.
Does anybody have access to manufacturing facilities? I'm
sure a charger
like this could retail for under a $100.00 if mass produced. There
is a
ready market (given our own experiences). Has anybody come across
a charger
like this that is already on the market?
Andrew Smithies
Wellington
New Zealand
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From: Duane Green (The Colony, TX)
Subject: Re: batteries
Our church has eight Shure SM58/SC24 handheld wireless
mikes that we use
in nearly every service. We use Energizer 9V batteries and have
had no
problems squeezing up to six hours of life out of each.
For peace of mind, I always put a fresh battery in the
Pastor's lapel
mike before each AM service and use it again for the PM service.
I never use fresh batteries during rehearsals, figuring
that if a
battery goes bad then, it's no problem to replace it. These particular
mikes have a built-in battery meter that checks battery life.
As a rule,
before each service, I check each one and if the meter reads less
than
half, I toss the battery and replace it with a fresh one.
We have had the same experience as Curt with the rechargeable
batteries.
I wonder why someone hasn't come out with a rechargeable with
a more
dependable power rating. If they did, they's make a mint!
Duane
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From: Curt Taipale (Taipale Media Systems, Inc.)
Subject: Re: batteries
Duane and all,
Where do you buy your batteries?
We bought our batteries from an industrial supplier. One
convenience with
that arrangement was that, should we find batteries with little
or no charge
- and it does happen! - all we had to do was set that battery
aside. Any
time I'd place an order, I'd be able to get a free replacement
for any bad
batteries that may have been in that batch.
Our "used" batteries were also kept for rehearsals
and soundchecks. And the
ushers would come by once in a while and ask for any used batteries
that we
had so they could give them away for kids' toys and the like.
Curt
curt@churchsoundcheck.com
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From: Don Clayton (Calgary, Alberta, Canada)
Date: Tue, 2 Dec 1997
Subject: Re: RE: batteries
We use an "industrial" version of Duracell called
Procell. It costs
about half the price of a Duracell. These batteries are only available
wholesale but the cost savings are well worth it.
We use them in our Samson VHF Diversity lapel. With 2 services
every
Sunday they last about 3 weeks. At the recommendation of our supplier
I
have never tried rechargeable's in any Mic.
Don
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From: Calvin Wilson (Garland, TX)
Subject: Re: batteries
Let me make sure I understand. Are you saying that if a
volt meter check
indicates a charge of less than 8.0V that the battery should be
replaced?
I've wanted to know this for some time. Is that voltage
accurate? Has anyone done
an actual study to determine the minimum acceptable start-of-church-service
voltage for a 9V wireless? As it is now, we use our handheld and
our belt pack
about 1 hour each twice a week. We replace the batteries "every
so often".
Usually when it seems like we are losing gain. That ends up being
about every
three to four weeks. I'd much rather check the voltages and replace
the batteries
when I hit the minimum acceptable voltage. I just need to know
what the minimum
is. Of course we could replace the batteries very week, but the
truth is in our
case that would be over kill.
Comments?
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From: Barry Birdwell (Nashville, TN)
Subject: Re: batteries
<"We tried to switch to some true 9V rechargeables
at one time, but even with
all of our support we never came up with a dependable system to
be sure they
were recharged properly.">
Rechargable batteries are the worst things to use if you
are looking for
full performance each time. Unless the battery is fully discharged
prior
to recharging, it will not fully recharge. They can also develope
a
"memory" of how much is needed to make them feel good
again and will only
take on so much. This is ok if you drain them the same each time
however
different drainings will produce varying recharge cycles.
Most modern day wireless systems are pretty voltage particular as you said.
<"As much as we want to save the money, we decided long ago that our pastor was worth the $1.50 per service for a fresh 9V Duracell.">
This would be my advise
Barry Birdwell
Birdwell Acoustics, Inc.
Nashville, Tennessee
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From: Robert Martin (Warner Robins, GA)
Subject: Re: batteries
Curt/List,
We also should buy stock in Duracell.
The Duracells seem to last about 33% longer
(that's 4 services rather than 3) than Energizers
in our pastor's mic. We tend to "recycle"
batteries that are too weak for his mic. by
using them in the music leader's handheld mic.
- it seems to be more forgiving than the pastor's.
One of my sound guys went to a seminar
recently and said that they recommended
the Duracell Powercell - I am unfamiliar with
these, do you know anything about them?
Has anyone tried the Lithium 9 volt batteries?
Robert K. Martin
martinrk@hom.net
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From: Duane Green (The Colony, TX)
Subject: Re: batteries
Curt,
The last time we bought batteries, a member of our sound
team got them
from Sam's Club. I don't know how the price compares with an industrial
supplier, but I think we paid around $1.50 each.
Duane
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From: Doug Benson
Subject: Re: batteries
Batteries, batteries. We have been using Duracell Alkaline,
exclusively for the past 6 years. That would be a tolal of about
2500
batteries and have had exactly 2 failures. That would be, batteries
that
were DOA or lasted just a minute or two. Most of the measure about
9.6V out
of the package. We use them down to 8.4 volts. I never want to
risk
having an altar call become a technical fiasco over being too
cheap to
change batteries.
Batteries below 8.4 volts are not discarded but kept in inventory
for
rehearsals. That is the best place to "bleed dry" old
batteries becaue
there is no audience and if the mic goes dead, "Who cares?"
Also, when other ministries come running up to you at the last
minute
wanting to "borrow" a battery, (childrens, youth, etc)
give them one of the
special ones you have set aside.
Doug Benson
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From: Michael Henderson (Houston, TX)
Subject: Re: batteries
Regarding 9V batteries. We have used several rechargable
brands for a number of years with no problems as long as 1) they
are charged overnite, 2) they are
changed out and replaced every 6 months.
I have compared the pastors wireless with duracell and
everready 9v's and see
only a tiny bit difference. Our wireless is a Samson and an Audio
Technica and both work fine with rechargable's from Sears or Radio
shack.
I am curious as to what the others that don't like rechargables notice when using them.
Mike Henderson
Sound coordinator
VCF Houston
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From: Curt Taipale (Taipale Media Systems, Inc.)
Subject: Re: batteries
Calvin,
Great question. I'd say use whatever system makes you comfortable.
We would
use old batteries for rehearsals and soundchecks, and then put
in new
batteries about twenty minutes before the start of the service.
How long
they lasted would of course depend on how long the service lasted,
and/or if
the wireless transmitter was kept on throughout the service. For
our
services, the transmitters might be on for over two hours. Also,
some
transmitters seem to suck batteries faster than others. So the
brand and
model of transmitter you're using is another variable.
In our case, there's no way I'd put a mic with an old battery
on our pastor
or worship leader and send him out in front of a couple of thousand
people
(or more). It's no more important for a mic to fail on a pastor
in front of
200 people versus 2,000 people, though it may be more embarassing
to the
sound team.
The most important issue for me was to not let the mic
fail during a
sensitive moment in the service, like the invitation. And think
about it -
if a mic's battery is going to give up, when's it going to happen?
If he
went into the service on a battery with less than a full charge,
the mic has
been on now for an hour or more, the charge is dropping lower
and lower until
finally it hits the point where the transmitter gain starts to
compromise its
signal to noise ratio for the RF signal. Eventually the audience
will start
to hear dropouts ("phfffft"sounds and loud pops). If
that happens during the
sermon, it's embarassing. If that happens during an invitation,
I'll be
disappointed in myself for allowing it to happen, and I'll probably
hear
about it from on high after the service or at the production meeting
later
that week.
I remember Marty O'Connor saying one time that he wouldn't
put a wireless mic
on his pastor - instead he used a cabled lapel mic because it
was much more
dependable. Marty was the tech director at Willow Creek Community
Church for
several years. (Any comments Marty?) Talk about batteries - that
church doub
le-miked their drama team! (Two wireless mic transmitters and
mics for
redundancy.)
All that to say, yes - the only time I'd use a 9V battery
with a charge of
about 8 volts would be maybe for a short, evening worship service,
or for
some less demanding events like a small group Bible study and
so on. I'd
always use fresh batteries with a full charge for the primary
services,
weddings, and so on.
And technically, those batteries should be checked with
a load to get the
proper voltage. But my guess is that most churches just check
the battery
with a voltmeter directly on the battery terminals. It may not
be precisely
accurate, but it's relative and it worked for us. (The invention
that Andrew
talked about would have been a Godsend for our church - I would
have bought
one sight unseen.)
Blessings!
Curt
curt@churchsoundcheck.com
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From: Randy Starkey (Pevely, MO)
Subject: Re: batteries
Calvin,
I think each wireless mike is going to fade at a different
voltage. You'll
probably have to field determine that for each of your mikes...
We have
several variants here.
--Randy
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From: Curt Taipale (Taipale Media Systems, Inc.)
Subject: Re: batteries
Randy,
That's interesting. Have you documented those variables?
If you have time
to document it, I think many on the list would be curious to see
a comparison
of those mfg/models and their relative ability to drain batteries
dry. Maybe
we can dub one the "battery eliminator".
Curt
curt@churchsoundcheck.com
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From: Randy Starkey (Pevely, MO)
Subject: Re: batteries
Curt,
I've never documented it, but I'll see what I can do. I
know our Beyer
Dynamic handheld works at lower voltages than does the Shure/SM58
handheld
we have, and the Samson (the oldest one we have) is somewhere
in between.
But let me see if I can get some voltage readings right when they
fade...
All our lapels (5 of them) are Shure's, so those are the same.
Randy
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From: Rick Chinn (Redmond, WA)
Subject: Re: batteries
I buy mine at Costco. They've got Duracells. Don't remember how much though.
There's an interesting article in this month's Popular Electronics. Compares different brands of alkaline batteries. worth looking at at the newstand, even if you don't buy. All the brands appeared to be close in terms of performance vs lifespan.
The reason that nicads have lower terminal voltage is that
they are based on
different chemistry than the alkalines. (Ni/Cd vs C/Zn). So, to
a transmitter
expecting an alkaline, a fully charged nicad looks like an alkaline
that
is on it's way south.
Radio Shack (among others) makes a battery tester that puts a load on the battery under test. Just measuring the terminal voltage with a voltmeter won't tell you much, as the thing that renders a battery useless at the end of its life is it's internal resistance, which rises. So, ohms law comes into play, and you drop more of the terminal voltage across the internal resistance than you get into the load; voila! that battery is now toast.
You can use a voltmeter as a battery tester if you hang a resistor across its input so as to load the battery under test. If you really wanted to be scientific, you could size the resistor so that it's value approximated the drain of the transmitter.
Or, you could just arbitrarily say: .....15 milliamps, and use ohms law to figure out the nearest 5% value. You'll need to work out your own limit voltages this way (however).
Rick Chinn
Uneeda Audio
------------------------------------------------------------------------------
From: Rick Chinn (Redmond, WA)
Subject: Re: batteries
Oh yes, one last thing:
You can get the industrial cells from somewhere like Graingers. You have to buy them by the box (but then, you go through them by the box...).
In my Newark catalog, the 9V energizer sells for $3.44 (1-24) and $3.32 (25-49). That's p/n 522, NEDA 1604A. The EN22 (NEDA 1604AC) is $2.41 (1-24) and 2.31 (25-49).
Duracells are shown at $3.28 and $3.16
Their Procells are shown at $2.22 and $2.14.
Graingers sells rayovac. their 9v alkaline is 2.52 (ea, 6pk) or 1.89 (ea, 72pk)
They also have a 'heavy-duty industrial battery' that is 1.30 (ea, 6pk) or 1.14 (ea, gross)
I'll check Costco and report back
Rick Chinn
Uneeda Audio
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From: Rick Chinn (Redmond, WA)
Subject: Re: batteries
OK. I went to Costco today. They win, hands down. A six
pak of 9V duracels
goes for 8.29, which is $1.38/battery. You even get a free battery
tester!
Rick Chinn
------------------------------------------------------------------------------
From: Calvin Wilson (Garland, TX)
Subject: Re: batteries
These are interesting suggestions. I'd use a multimeter instead and go one step further...
To get the correct value of the load resistor:
1. Put the meter in series with one pole of the battery and the transmitter terminal. Then setup the meter to read milliamps and turn on the transmitter. Get the current reading.
2. Put the meter in parallel across the battery terminals. Setup the meter to read volts and turn on the transmitter. Get the voltage reading.
3. Use Ohm's law to calculate the load resistance.
BTW if anyone needs it here's Ohms law: I=E/R
In this case it would be transposed to: R=E/I
Calvin
P.S. Don't forget to do the units conversion: milliamps to amps. With enough digits on the meter, you could read the current directly in amps.
------------------------------------------------------------------------------
From: Andrew Smithies (Wellington, New Zealand)
Subject: Re: batteries
<"I might be able to help out with something like
this. I purchased a
bunch of 68HC705J2s for a project that I never did.">
Bob,
I take it that you're familiar with building / programming
these things.
I'm rather busy and was hoping someone might like to make this
fly. It's no
trouble to dig out the needed info on how to do this. I've also
had some
work to do with a commercial unit for testing 500Ahr 48V battery
banks as
used for standby power for telecommunications equipment.
Send me a note if your keen (or anybody else too) to make some
useful
chargers.
Steve,
<"Our cordless phone uses a lead acid battery.
The manufacturer suggests
charging the battery often ,not letting it drain all the way down,
because
it works better and lasts longer. I have looked for a 9V version
with no
success.">
Unlike Nicads lead acid cells require the terminal voltage
to be maintained
or the surfaces on the electrodes will deteriorate. For a cordless
phone
this is no problem as it is almost always left on the charger
when not in
use. Have you ever left the lights on in your car and really flattened
a
new battery? Did you notice that the battery was no good after
a year or
so? When normally you can get 5 or more years.
As a lead acid likes to be kept trickle charged, a Nicad does NOT.
Also. Look out for the metal hydride type batteries. They
have more
capacity but an even faster self discharge. When a manufacture
goes for a
high capacity cell it is often at the expense of self discharge.
A metal hydride is a bit like a Nicad but be careful when
charging them.
There is distinct voltage characteristic that is often used to
determine
full charge. You will either under or over charge the cells if
you get it
wrong.
*Some Nicads will be flat in two days!
*Also Nicads have a amp hr rating that is less than a zinc carbide.
*Zinc carbide cells have a self life of 6 months (ie 6 months
after
manufacture they will be half flat.) Alkaline cells have a 3 year
shelf
life. Also alkalines have an amp hr capacity that is more than
double the
zinc carbide.
If you don't have the means to care for Nicads then use
alkaline batteries.
Less $ per watt and more shelf life so you get to use the energy
you buy.
Here is a little aside to do with Nicads.
Nicads have very low series resistance when charged. --rick chinn
talked of
this "as the thing that renders a battery useless at the
end of its life is
it's internal resistance, which rises ". The next time you
have a flat
battery in your car go fetch 10D size Nicads (charged). Make a
nice row of
them (end to end) along the radiator (keeps em straight) and then
hook em
up to the car battery and at the same time get someone else to
start the
car. You have about 5 seconds of good cranking and then all the
little
cells will be approaching a smoldering mess! But hey, who is concerned?
You
car is running. If you car has an engine over 3litre then life
may not be
quite as good. I have a work mate who did this. The batteries
where all
right after. All be it a bit warm.
Andrew Smithies
Wellington
New Zealand
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From: Calvin Wilson (Garland, TX)
Subject: Re: batteries
Hey, has anyone thought about those "rechargable"
alkaline cells? Are they
really alkaline? what's the fully charged voltage? Just wondering.
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From: Robert Stanley (Topeka, KS)
Subject: Batteries for wireless & Cassette decks
We are finally reaching a point that we are using enough
wireless mics that
the Duracell supply from Sams is no longer feasible. What rechargeable
batteries are you using that you have had good luck with? I'm
especially
concerned about "memory" problems as batteries will
often not be run all the
way down before they are recharged.
Secondly, any input on cassette decks to be used as a play-only
deck. One of
the request I've had from a couple of vocalists is pitch control,
so if
you've had good experiences with any decks with this feature,
I'd be
interested.
TIA,
Robert Stanley
Topeka First Nazarene
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From: Bill Lockhart (Palmetto, FL)
Date: Sun, 1 Mar 1998
Subject: Re: Batteries for wireless & Cassette decks
We'va used a Nakamichi with good success. Pitch control, excellent quality.
------------------------------------------------------------------------------
From: Blake A. Engel (Chicago, IL)
Subject: Re: Batteries for wireless & Cassette decks
<"Secondly, any input on cassette decks to be used
as a play-only deck.
One of the request I've had from a couple of vocalists is pitch
control,
so if you've had good experiences with any decks with this feature,
I'd
be interested.">
Sure, my favorite has been the MR2 by Nakamichi (is that
spelled
right?!) smooth, has pitch control, can wire up an external remote...never
fail (in the studio or installed at a church--only standard belt-changes
were
ever needed.)
Blake A. Engel (A.K.A. "Sound Guy")
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From: Bob Enlow (Norwalk, OH)
Subject: Re: Batteries for wireless & Cassette decks
Robert Stanley,
A thorough discharge is a must if you are to maintain life. It should be done frequently, but not necessarily after every use. It's done to "remind" the battery of its real cycle.
Unless you can digitally change pitch, I'd stay away from
that. All the
tapedecks I've seen just change the motor speed, which speeds
up or slows
down the tape. If you can do it digitally, you can move it about
four steps
and still not sound too bad, unless you have background vocals,
then it
begins to sound weird. Back to the standard deck with pitch control,
I
don't think the little you can change it without seriously affecting
the
speed is enough to make that big a difference. I sing to background
tapes,
so I speak from my own experience on both of these item.
Bob Enlow
RESOUND Co.
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From: Calvin Wilson (Garland, TX)
Subject: Re: Batteries for wireless & Cassette decks
Along these same lines, I'm wondering if anyone has used
the rechargable
alkalines. Any comments?
------------------------------------------------------------------------------
From: Steve Harper (Norfolk, VA)
Subject: Re: Batteries for wireless & Cassette decks
Be careful with rechargeables! Duracell Procells for me.
Tascam 112MkII cassette deck has been great- not cheap
though. I have always
liked Tascam and needed balanced outputs. Editorial: always used
balanced lines whenever you can! The optional balancing kit went
in very easily.
Steve Harper
First Baptist Church of Norfolk
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From: Jens W. Skov (Denmark)
Subject: Re: Batteries for wireless & Cassette decks
<"...A thorough discharge is a must if you are to maintain life. It should be done frequently, but not necessarily after every use. It's done to "remind" the battery of its real cycle.
That's not the whole truth.
If you use the right charger-algoritm you won't need to discharge.
It's not available for normal rechargeables yet, but I think it
will
come.
--
Jens W. Skov
St.Sc.E.E.
Technical University of Denmark
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