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Author Topic: On rechargeable batteries for high profile RF mic/IFB/IEM use  (Read 5707 times)

Dave Stevens

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On rechargeable batteries for high profile RF mic/IFB/IEM use
« on: December 10, 2008, 04:44:36 pm »

This is taken from the "where do I get cheap batteries thread" and Mac if you think it needs to be integrated into that thread please do.  This is direct experience from almost 3 years on large scale modern human circus style production shows on the Strip in Las Vegas.  In addition to being one of the all around mixer type dudes at the  show, I'm also what is called the "battery czar".  I ride heard over the rechargeable batteries used for 158 radio IEM/IFB packs on 22 freqs as well as batteries for 22 radio mics.  We are presently migrating out of the 700mHz band (to the tune of well into six figures for our show alone) and will go to all rechargeable batteries when the move is complete just after the first of the year.  We currently are using 9v and AA rechargeable and were planning on using AAA NiMH but suspended the transition as the new mic packs are the 5200 series and use a single AA.  Once the migration is complete we will eliminate the use of alkaline cells in all of our radio gear which includes more than 200 Motorola radios, 16 UHF hoist controls and 52 BTR 800 packs in addition to the IFB/IEM and mics.

We currently use the Sennhieser Panasonic NiMH sleds and charging system in the G2 series listen packs but most of our inventory is 3000 series with G1 style packs.  The 9v are the iPower Li-polys that are at Thomas distributing.  We stock and manage an inventory of just over 200 iPower 9v in the show at any given time.  At this point only 16 of the packs are G2 series AA but it will change to all AA G2 series style packs soon.  I've done extensive testing on AAA NiMH, AA NiMH, 9v NiMH and 9v Lipo cells and have documented run time and overall cell life.  We use a Fluke 199C with computer logging interface and a jig I made to plot use curves in real world conditions.  

To be short, we haven't found any 9v rechargeables with quite as long a run time as alkaline 9v.  To compensate we use two rotations of batteries swapping them for each show.  We have calculated a savings of about US$15,000 per year using this method for 9v cells alone.  There are issues with an out of the box or within a couple week failure rate of about 12% but we can usually test and segregate those cells prior to failure during the performance.  We have more ear piece failures than battery failures due to the extreme conditions in which they are deployed.  We try to rotate the lipo cells out every six months or so as they seem to deteriorate after that though we do have some cells that are more than a year old.

In testing and real world performance we have found the AAA and AA cells operate as well as alkaline in our applications.  You do need to condition the NiMH cells periodically and make sure they don't get "soft" but routine testing and maintenance will take care of it.  We consider our technical, artistic and creative standards to be among the best in the industry.  If we are able to use rechargeable cells in these apps I see no reason why others can't as well.

Dave
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Mac Kerr

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #1 on: December 10, 2008, 05:53:44 pm »

Dave, thanks for sharing the results of your research. Can you share what you have found to be effective "conditioning" of rechargables? That is quite a battery inventory you are dealing with, how do you keep track of bad cells?

Mac
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Andrew Broughton

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #2 on: December 10, 2008, 06:13:32 pm »

Dave, thank you for supporting what I have been saying for years about rechargeables.

I'm curious if you ever tried the PowerEx batteries and chargers?
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-Andy

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http://www.checkcheckonetwo.com - Saving lives through Digital Audio, Programming and Electronics.

Mac Kerr

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Re: On rechargeable batteries
« Reply #3 on: December 10, 2008, 06:23:58 pm »

Dave Stevens wrote on Wed, 10 December 2008 16:44

 We consider our technical, artistic and creative standards to be among the best in the industry.  If we are able to use rechargeable cells in these apps I see no reason why others can't as well.

Dave

It may be because your technical standards are high that the system works for you. In a facility situation like your's, even though you are at the sharp end of the stick, you have tight control over the handling and maintenance of the batteries. I fear that in the area of one offs like I deal with day to day it would mean relying on the shop for that quality control, which may not inspire confidence. There may also not be time for battery charging when rehearsing or in show mode from 7am-6pm. Batteries can charge overnight, but during the day there may be a large demand. Keep us informed this is an important issue.

Mac
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Scott Helmke (Scodiddly)

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Re: On rechargeable batteries
« Reply #4 on: December 10, 2008, 07:06:22 pm »

It works because the company is in complete control of the batteries, as Mac says.  As more of a rental house there's no way we could manage that.  People would be throwing away our batteries to put in alkalines, or at the absolute best not keeping track of things well enough to make the system work.

It's great that it can be done, though.

Steve Weiss

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #5 on: December 10, 2008, 07:44:41 pm »

We have used the Ansmans since we opened in 2004. Dave was just starting his experiment on lifespan here when he jumped shipped. I can say that just from casual observance, he is spot on. We change the 9 volts on six months and AA maybe 18 months.

We only use 40 9 volt per day and have 2 sets for rotation every other day.
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Dave Stevens

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #6 on: December 10, 2008, 09:00:03 pm »

There are other factors that play into the use of the cells and that needs to be taken into account.  From a technology based view there is no reason not to use rechargable cells. The technology is mature and progressing more everyday.  For some apps it might be best to use low self discharge cells so they have some shelf life.  Another thing to factor in is the quantity required and the frequency (as in number of times) the device is used.  There might be logistical reasons why rechargeable cells might not be appropriate but particularly in the case of AA and AAA they perform as well as the alkaline counterparts in our tests and real world deployments.

When I joined Steve's show I was hesitent about using them, mostly for the same reasons everyone else has had.  The technology, particularly over the last few years with AAA and AA has improved greatly.  Not so much with 9v though many if not most modern designs no longer use 9v.  Our typical mic pack run duration is about 8 hours.  While alkalines still run longer than our rechargeable cells, the rechargeables run well long enough (about 9 hrs plus).  Conditioning the cells are done in the chargers and manually during our dark periods.  It is also during those times we condition the BTR batteries and are alway cycling and conditioning Motorola batteries.  On a show of this scale with so much riding on communication you can not skimp on good battery management.  Of course, that's not the case for all users and many might not be able to justify the logistics or cost conversion.

We use the PowerEx AAA and AA as well as the iPower 9v.  We tried the PowerEx 300mAH 9v and while the quality and consistency of the build was better, it didn't run as long as the iPower.  The build quality and QC of the iPower is pretty spotty and though covered by warranty for the amount that fail or are DOA it's not worth the paperwork on our purchasing side to send only a few back.  They basically pay for themselves in about 20 uses and with the directive from the producers to be as eco friendly as possible it's a good fit for us.

Dave
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trace knight

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #7 on: December 10, 2008, 09:08:01 pm »

Hey Dave, welcome back to the trenchs, Battery Czar, pretty good title, At least maybe they will save enough in batterys to give you a raise! This is really a great thing for such a huge show that use's so many cells, go green young man, go green. I could also never use rechargables, they would all get tossed, no one pays attention, it's good your on top of it, in a controlled situation.Have fun, and Happy Holidays.

tk
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Andrew Broughton

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #8 on: December 10, 2008, 10:10:23 pm »

Dave Stevens wrote on Wed, 10 December 2008 19:00

For some apps it might be best to use low self discharge cells so they have some shelf life.

The new PowerEx Imedion http://www.mahaenergy.com/store/viewitem.asp?idproduct=426
interest me for that reason.

Quote:

Our typical mic pack run duration is about 8 hours.  While alkalines still run longer than our rechargeable cells,

Depending on the drain curve, rechargeables can last longer than Alkalines, as is the case in my experience with the PowerEx AA batteries.

Quote:

Conditioning the cells are done in the chargers and manually during our dark periods.  It is also during those times we condition the BTR batteries and are alway cycling and conditioning Motorola batteries.

Some people may not realize that conditioning of NiMh should be done very infrequently (if ever) to get the maximum life out of them. NiCads are a different animal - hopefully you don't have any of those!

Quote:

We use the PowerEx AAA and AA as well as the iPower 9v.  We tried the PowerEx 300mAH 9v and while the quality and consistency of the build was better, it didn't run as long as the iPower.  The build quality and QC of the iPower is pretty spotty

I concur. The iPower stuff I tried was poorly built. I've not had any problems with the PowerEx stuff. I especially like their chargers.
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-Andy

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http://www.checkcheckonetwo.com - Saving lives through Digital Audio, Programming and Electronics.

Dan Johnson

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Re: On rechargeable batteries for high profile RF mic/IFB/IEM use
« Reply #9 on: December 10, 2008, 10:17:15 pm »

Dave Stevens wrote on Wed, 10 December 2008 20:00

For some apps it might be best to use low self discharge cells so they have some shelf life.

Have you tried the PowerEx low-self-discharge batteries Dave?  I'm wondering what kind of battery life these get compared to the standard PowerEx batteries.
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