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[JAOgann]

We are looking into the "low-self-discharge NiMH" (LSD MiMH) AA batteries now being offered. They don't loose their charge quickly when stored and come pre-charged.

Has anyone tried these on UHF AA battery powered wireless mics? There is a lot of info on the forum on 9V but not much on AA's.

We use Shure SLX's.

Some come with "smart" chargers so batteries can be left in them after charge is complete.

These are the brands and models in question:
   * Duracell Rechargeable Pre-charged
   * E8GE 1000 Ready to Use Rechargeable
   * EasyPix Pre-charged Rechargeable
   * Panasonic R2 Technology Rechargeable
   * Powerex Imedion
   * President's Choice Rechargeable
   * Rayovac Hybrid
   * Sanyo Eneloop
   * Sony CycleEnergy

[Taylor Phillips]

I don't have any experience with rechargeable AAs in mics, but I use the Duracells you mentioned for my camera.  I work as a photographer for car dealers for my day job, and I haven't a problem getting 600-800  pictures(~50% w/flash)on one charge of those batteries.  That's usually in one day though, and I recharge them every night, so I don't really know how they'll do when fully charged on Sunday morning, used for a couple hours then sitting all week.  They do work better than regular NiMH or alkaline batteries for my use of them.

[Darin Brunet]

Shure ( http://www.shure.com/americas/products/wireless-systems/slx- systems/slx1-wireless-bodypack-transmitter ) states that "rechargeable" AA batteries are acceptable for use in both the SLX1 and SLX2 transmitters. However, they also state that the 8+ hours of use are with alkaline batteries, not the rechargeable kind. I would expect that NiMH batteries would provide acceptable performance but maybe not for a full 8 hours of use, since you will be short on voltage. Remember, they do not provide a full 1.5V per cell. I have used them but usually recharged them after every 3-4 hours of use (2+ hours on Sunday, 1+ hours on Wednesdays), putting them in the recharger after Wednesday evening service. BTW, since I remote mount my receivers, the transmitters only go for about 15-20 ft. YMMV.

[Christy L Manoppo (okky)]

we currently use energizer rechargeables for all of our wireless mics, senn ew500g3 and shure's UR.
So far, 6hrs plus of use every sunday, we don't encounter any problem yet.

also, the battery life depends on some factors;
- transmitter power level (most says 10mW, 50mW)
- recharging habits. (make sure it discharge completely before any recharging cycle begins).

[Darin Brunet]

Christy L  Manoppo (okky) wrote on Sun, 18 July 2010 23:27

we currently use energizer rechargeables for all of our wireless mics, senn ew500g3 and shure's UR. So far, 6hrs plus of use every sunday, we don't encounter any problem yet. also, the battery life depends on some factors; - transmitter power level (most says 10mW, 50mW) - recharging habits. (make sure it discharge completely before any recharging cycle begins).

There is no need to completely deplete an NiMH battery before recharging. NiMH batteries do not have the "memory" that older NiCD batteries did.

From Energizer:  Battery "memory" is a loss of battery capacity due to partially discharging and recharging repetitively without the benefit of a full discharge. This was evident with early nickel cadmium (NiCd) rechargeable batteries and is not found in nickel metal hydride batteries (NiMH) currently manufactured.


I continually charge and recharge the NiMH batteries in my DSLR cameras, cell phones, AA & AAA's and have never had a problem.
~DB

[Jonathan Johnson]

Darin Brunet wrote on Sun, 18 July 2010 22:43

BTW, since I remote mount my receivers, the transmitters only go for about 15-20 ft. YMMV.

Transmitter-to-receiver distance doesn't directly influence battery life, but I suppose that a weak battery would be more usable if the distance was short -- on an analog-tuned transmitter.

If your transmitter uses digital tuning, chances are good the unit will shut off when the voltage drops below the level necessary to operate the chips, and you won't notice much of a difference at all in transmission distance. Those same batteries that are too weak to operate the digital-tuning transmitter just might work OK for a while longer in an analog-tuning transmitter.

If the transmitter allows you to adjust the RF power output, you may be able to optimize the battery life.

[Darin Brunet]

Jonathan Johnson wrote on Mon, 19 July 2010 01:21

Darin Brunet wrote on Sun, 18 July 2010 22:43 BTW, since I remote mount my receivers, the transmitters only go for about 15-20 ft. YMMV. Transmitter-to-receiver distance doesn't directly influence battery life, but I suppose that a weak battery would be more usable if the distance was short -- on an analog-tuned transmitter. If your transmitter uses digital tuning, chances are good the unit will shut off when the voltage drops below the level necessary to operate the chips, and you won't notice much of a difference at all in transmission distance. Those same batteries that are too weak to operate the digital-tuning transmitter just might work OK for a while longer in an analog-tuning transmitter. If the transmitter allows you to adjust the RF power output, you may be able to optimize the battery life.

Yes, I absolutely agree with you. I did not mean to imply that distance affects battery life. My poor choice of wording Thanks for the clarification! I do remote mount my receivers and amplifiers for other reasons... just NOT for battery life.
~DB

[Arnold B. Krueger]

Darin Brunet wrote on Mon, 19 July 2010 03:43

BTW, since I remote mount my receivers, the transmitters only go for about 15-20 ft. YMMV.

I was forced to do that with our previous Samson UHF diversity system. They all became illegal, and we replaced them with Shure SLX and AT 3000-based systems.

Remote mounting receivers is pretty nasty because you lose so much feedback about how the link is running. It eliminates the benefits of remote battery status indicators.

In retrospect, the lack of frequency agility was the probable cause of the range related problems that we had with the Samsons. Of course both of the new systems are frequency agile.

I've been able to simulate the same symptoms we had with the Samsons by picking the wrong frequencies with the new ATs. The Shures are self-setting, and never seem to put themselves onto troublesome frequencies.

Getting back to batteries, we've never risked rechargables. The improved battery life with the new equipment, and the switch to AAs is a tremendous benefit.

[George S Dougherty]

I run the 15 minute charge Energizer types. I do a fresh charge on a Saturday and they're good for 3 services and about 5 hours of use through Wednesday. We pickup a new set every 6-12 months.  $12/4AA's

[David Sharp]

I use these batteries:

http://www.thomasdistributing.com/shop/ansmann-2500-aa-low-d ischarge-nimhbrfour-batteries-per-pack-p-1880.html?SP_id=&am p;osCsid=a98rm8a91donrsllit8gi3gna7

With this charger:

http://www.thomasdistributing.com/shop/ansmann-energy-8-rech argeable-battery-chargerbrincludes-4-free-2850mah-ansmann-aa -batteriesbr1-eight-cell-ansmann-battery-holder-p-550.html?S P_id=&osCsid=a98rm8a91donrsllit8gi3gna7

In a Sennheiser G3. We've been using them for about 2 months no with no issues. I also use a 9v rechargeable in a Shure model handheld. Only issue I've had there is with a negative terminal detaching from one of the batteries.

- David

[Christy L Manoppo (okky)]

Darin Brunet

There is no need to completely deplete an NiMH battery before recharging. NiMH batteries do not have the "memory" that older NiCD batteries did. From Energizer: Battery "memory" is a loss of battery capacity due to partially discharging and recharging repetitively without the benefit of a full discharge. This was evident with early nickel cadmium (NiCd) rechargeable batteries and is not found in nickel metal hydride batteries (NiMH) currently manufactured. I continually charge and recharge the NiMH batteries in my DSLR cameras, cell phones, AA & AAA's and have never had a problem. ~DB

Yes. Thanks Darin for pointing that  out. But this is just a matter of habit of mine.

The only problem we encounter when using rechargeables is, they have a steeper voltage loss curve when they already spent all their "energy". Unlike alkalines, which seems to have a broader curve.
cmiiw

[Darin Brunet]

Arnold B. Krueger wrote on Mon, 19 July 2010 06:10

Darin Brunet wrote on Mon, 19 July 2010 03:43  BTW, since I remote mount my receivers, the transmitters only go for about 15-20 ft. YMMV. I was forced to do that with our previous Samson UHF diversity system. They all became illegal, and we replaced them with Shure SLX and AT 3000-based systems. Remote mounting receivers is pretty nasty because you lose so much feedback about how the link is running. It eliminates the benefits of remote battery status indicators. In retrospect, the lack of frequency agility was the probable cause of the range related problems that we had with the Samsons. Of course both of the new systems are frequency agile. I've been able to simulate the same symptoms we had with the Samsons by picking the wrong frequencies with the new ATs. The Shures are self-setting, and never seem to put themselves onto troublesome frequencies. Getting back to batteries, we've never risked rechargables. The improved battery life with the new equipment, and the switch to AAs is a tremendous benefit.

With the short distance, I have never had any link problems. Also, the receivers I have do not have remote battery indicators, so no problem there, I routinely replace batteries on a schedule. I am using Shure wireless mics and body packs and have never had any issues of any sort with frequency problems. I remote mount my receivers and amps to limit the distance and obstacles the transmitters face and simply run balanced line back to my board. Remote mounting my amps makes for shorter speaker wire runs. They are out of the way and cannot be easily adjusted by novices/volunteers. They are fan cooled and have air filtration around them. Again, just balanced lines from the desk to the amps. My gain structure is such that I do not have issues with amp clipping. At the levels I run the PA, distortion and clipping are never present. This is just how I set things up, perhaps others do it differently but it suits me fine.

[Darin Brunet]

Christy L  Manoppo (okky) wrote on Mon, 19 July 2010 23:35

Darin Brunet There is no need to completely deplete an NiMH battery before recharging. NiMH batteries do not have the "memory" that older NiCD batteries did. From Energizer: Battery "memory" is a loss of battery capacity due to partially discharging and recharging repetitively without the benefit of a full discharge. This was evident with early nickel cadmium (NiCd) rechargeable batteries and is not found in nickel metal hydride batteries (NiMH) currently manufactured. I continually charge and recharge the NiMH batteries in my DSLR cameras, cell phones, AA & AAA's and have never had a problem. ~DB Yes. Thanks Darin for pointing that  out. But this is just a matter of habit of mine. The only problem we encounter when using rechargeables is, they have a steeper voltage loss curve when they already spent all their "energy". Unlike alkalines, which seems to have a broader curve. cmiiw

Christy, with due diligence, I regularly recharge all of the batteries we use in our wireless products. I have never had any issues. AA's should last for more hours of usage than you are actually requiring of them. The only reason I would choose to use 1.5V alkaline type is if the unit specifically requires 3V and will not operate reliably on 2.4V. I choose to use Energizer 2500mAh 1.2V NiMH AA batteries.

[Shawn_Lockwood]

Some interesting discussion here on this topic.  I'd like to share my experience with the rechargeables vs. alkaline battery usage.  My comments are based on several thousand batteries of use at a community college using both rechargeables and alkalines.  

First - if it's a critical situation where you have to depend upon the mic working - use alkaline.  If it's OK to stop what's going on and replace batteries or swap mics then rechargeables are fine.  I make this statement based on the results that I have observed (over a 16 year period) and the related data provided by independent testers as well as that by that provided by Energizer on their web site.  I compared Energizer's info with various tests and charts found on line and they mirror each other.  No...I'm not associated with Energizer in any way.  Second - use Energize or Duracel Pro's for your batteries.  Oh, by the way, there isn't any difference between Energizer consumer batteries and the "Industrial" version.  Both are the same E91 (industrial is labeled as EN91) battery for the AA's and likewise for their 9 volt versions.  The labeling is different and you get a protective cap on the 9 volt version's terminals for the industrial version but that's it (AA's don't have a need for the protective caps).

What is my firm belief in using alkalines during a critical situation based on?  Look at the charts, Engergizer's or anyone else's and you will see the difference between the rechargeables and the alkaline in the area on the chart where the battery is beginning to lose it's ability to provide usable power.  The rechargeable will have a drop that falls of dramatically and with little to no time for use beyond that drop off point.  Alkaline's are much more forgiving with a  gentler drop off and the assurance that it will last for a while longer (my experience shows that it will be around 30 minutes of use or maybe a little less).  I get a solid 8 hours out of two AA's in my belt pack transmitters (Audio-Technica 3000 series mics with a current draw of around 180 ma/hr) with the same for the 7000x series 9 volt versions.  I have gotten upwards of 10 hours or a little more but I never push things that far when it's not just practice.  I do battery checks prior to each use and know exactly how long I can expect a battery to last.  Additionally, you will find that rechargeables lose upwards of 4% per day of charge if left off of a charger/installed in a mic.  As long as you stay within the shelf life of the alkalines you won't have to worry about it's capacity/ability to perform as desired.  

Rechargeables are only good for so many cycles.  I've found that the "1000's" of cycles advertised has never held up for any rechargeable I've every used.  You can not predict with any certainty when a rechargeable will fail to adequately hold a charge.  All of the chargers I've used do not reliably indicate what the true status of the battery's final charge is except in the case of a bad/depleted battery.  Measuring the after-charge voltage can be an indicator but still doesn't tell you a lot about a battery.  I've had rechargeable batteries that measured a solid 1.4 volts or close to it that didn't hack it under load in a transmitter for anywhere close to the amount of time it should have.

All this being said - am I disputing the experience others have had with rechargeables?  Absolutely not!  If you've had a good experience with them and they work in your situation, then take advantage of the cost benefit.  If you've ever had the special for service ruined because the mic died or had the pastor's sermon sputter in mid-message due to bad batteries then you'll know why I promote alkaline use.  I've never had a mic that has had a pre-show battery check die on me mid-show.  I do shows at my college where I can't afford to have a mic die because of batteries.  However, I don't have a problem with stretching out a battery's life for non-critical situations.

I haven't found any (affordable) batteries that beat Engergizers or Duracell Pros (don't use the standard Duracells because they simply don't measure up).  Buying batteries in bulk knocks the cost down to a very affordable amount when compared to buying them off the shelf at Wally-World.

I hope my experience with the above will help with the use of rechargeables/alkaline batteries.  I sure wish that rechargeables were reliable and long-lasting.  It would help my budget a lot.  

[George S Dougherty]

Shawn Lockwood wrote on Thu, 29 July 2010 20:25

I hope my experience with the above will help with the use of rechargeables/alkaline batteries.  I sure wish that rechargeables were reliable and long-lasting.  It would help my budget a lot.

There's nothing in your response that says they can't be reliable and relatively long lasting.

I will say, if you're using 9V, it seems too much of a hassle to me as the 9V rechargeable must be slow charged due to the multiple small cells within the battery.  Attempting to fast charge them like the 15-minute AA's would only cause them to explode.  At that point you'd always be dealing with a slightly older charge on the battery and if you don't have multiples that stay charged, forgetting to charge a battery beforehand means you're SOL.  In my experience, managing the charge on multiple sets of batteries for multiple units and ensuring a proper rotation is eventually an exercise in futility unless your ministry is staffed entirely by anal retentives or one person goes to the extra effort to manage it themself.

Most of the newer chargers are AA only and intelligently turn themselves off so as not to overcharge the battery.  That's a required feature in dealing with rechargeables.  As you noted, 1000's of charges is unrealistic.  100 charges for the high speed chargers is very realistic.  The # of charge cycles actually drops the faster you charge them, but they become much more convenient to use.   For a typical church with one to two services a week, one year's worth of use and then planning for replacement should provide reliable use, reduced waste and some decent cost savings.  At ~$12/4AA assuming even 50 charges or ~1 year of weekly use gets you a cost of about 6 cents per battery, per charge.  Alkaline batteries look to be in the $.30-.40 range in bulk and for reliability I still replaced them every week after 4-5 hours of use.

Everything you mentioned as a reason not to use rechargeables would be directly caused by using them for too many charge cycles based on the speed of charging and improper charging practices.

Charging them just prior to a service guarantees a fresh charge and puts control back with the current operator rather than depending on someone else to have properly done their job many hours beforehand.

[Brian Ehlers]

Building on what Shawn said:

1/  The voltage vs. energy curve of rechargeables makes them inherently very difficult to predict how much longer they will last before needing a recharge.  It doesn't matter if it's the battery indicator circuit inside your wireless transmitter or a human holding a volt meter.  With rechrageables you get less warning of "the end," and the accuracy of your prediction of when the end will occur is less than with alkalines.

2/  As they age, rechargeables hold less energy and their discharge curve becomes even less predictable.  Their constant use and handling also makes them more likely to develop a mechanical failure (short or open).  For these reasons, it is prudent to replace rechargeables BEFORE they become a problem, just as you do for alkalines.

There's nothing wrong with using rechargeables if they fit your needs.  Just don't kid yourself into thinking they are equal in performance and reliability to alkalines.

For me, the hassle of removing and recharging them all the time (and the risk that the last guy forgot to recharge them) rules them out.  My church uses 2 - 5 wireless mics per service, I throw away (dispose of properly) the alkalines well before they're drained, and still we use only about $50 worth a year.

[Kent Thompson]

Most of the problems people have with rechargables come from unreasonable expectations.

Do they last as long maybe not. So do not expect them to go through as many services. Have a rotation stock on hand so that you always have fresh batteries available to use.

Make sure that they are properly charged with a proper charger that shuts off when they have a full charge.

As Brian stated make sure you replace them when they start aging.

[Mike Jaspers]

I want to address the rechargeable battery debate here.  Our church started to use rechargeable AA and 9v batteries after the economy tanked to save money on batteries.  Also, it has been said that rechargeables are a lot easier on the environment.

We use the Maha Powerex 2700mAh AAs and the iPower US 500mAh 9 volt.  

I use(d) the 9v batteries in PSM 700r(now updated to Sennheiser) product as well as ULXP product.  I have not had a battery die on me yet.  I replace my batteries roughly after 2 uses (6-8 hours, depending), alkaline or rechargeable.  The cheapest I was able to find good alkalines was about $1; the iPower batteries are $18/ea.  So, they make up their value after about 20 charges.  Charge time is usually under an hour.

The Powerex are in use for Shure UHF-R transmitters and Sennheiser g3 receivers.  Freshly charged, they last at least as long as the Procell or Energizer product.  No failures as of yet, either.  I bought some extra batteries so that I could cycle through the product and have enough spare in case I did not have enough time between charges.  I always slow charge the batteries and it takes anywhere from 1.5-4 hours.  Not including the charger, they make up for their cost after 11 uses.  

I still use alkaline AA in our UR1 bodypacks, but only because the pack does not latch well when using the rechargeables.  Since I change the batteries every time for our Pastor, I am able to use old alkalines in other bodypack situations (baptistry, etc.).  

We saved about $1000 this year using rechargeable batteries.  Hope that helps.

Sincerely,
Michael D. Jaspers
Director of Technical Services
First Baptist Church of Springdale

[Paul Wilson]

We use some rechargeable batteries and some regular batteries. Obviously the regular ones hold a charge for longer, but knowing when to change them is exactly the same. For me, when the mic gets below full/three bars/whatever battery indicator you have its time to change them.

The fact is once they get below three bars, for instance, they tend to die faster. For example...it might take three hours of use for the mic to go from three bars to two bars and only one hour more for the batteries to completely die. So keep that in mind.

The other thing to realize is that rechargeable batteries still need to be replaced from time to time. It is NOT once you have them you are set for life. Just like a laptop that can't hold a charge after so long a time such is the case with any rechargeable batteries....eventually they need to be changed.

[JAOgann]

Thanks to all of you who commented. Some excellent info.  Jim O

[Don Boomer]

Here's my 2 cents ...

I've had some good luck with NiMH rechargables.  It is very important to get the correct charger for the batteries you choose to use, they are not as interchangeable as one might think.

How long they last in a wireless depends on their mAh rating ... bigger is better.  You do have to make certain that large capacity batteries actually fit your mics.  I have seen some that exceed the diameter spec for AA batteries and do not fit properly.

The other thing is that NiMH and Alkaline discharge at different rates so the battery meters in your units may not respond correctly.

Don Boomer
wireless sales engineer
Line 6, Inc.

[Bill Beach]

we recently went to the Sanyo Eneloop and love them.  we have the smart chargers and leave the batteries there until needed.  the previous battery was also slightly larger than a 'standard' AA and therefore caused problems closing the battery compartment.  not an issue with Eneloop.

[ProSoundWeb Community]