Recomendations for Rechargable Batterries and Charger?

[tootallll]

I've been searching the net trying to find the best forum to ask these questions and came across this forum.

Here's my situation, I recently started working a sound system with 12 wireless microphone systems. Each transmitter uses 2 AA 1.5V batteries for a total of 24. The rechargeable batteries currently used are lasting about 45-60 minutes in the transmitters...I think they are Ni-MH. I'm sure there are rechargeable batteries that would last longer I just don't know what brand or where to buy them.

I would be recharging them after each performance and performances are twice weekly. Any suggestions on a specific battery brand that might give me extended use? Should I purchase Ni-MH, Ni-CD or Li-Ion batteries? Also, what charger would you recommend? I would be recharging them after each performance and performances are twice weekly.

Thanks!
Mike

 

[kirby]

Just my suggestion

Charger : MAHA MH-C801D http://thomasdistributing.com/shop/...html?SP_id=&osCsid=gk612rnlum0gc28t589q16u3g4

AA Batteries : Sanyo 2700mAh http://thomasdistributing.com/shop/...ml?SP_id=78&osCsid=gk612rnlum0gc28t589q16u3g4
or Powerex 2700mAh http://thomasdistributing.com/shop/...html?SP_id=&osCsid=gk612rnlum0gc28t589q16u3g4

 

[mdocod]

I disagree with the suggestion to use 2700mAH cells, while they have their place and some of them seem to hold up ok, I'm of the understanding that a wireless microphone failing in the middle of a performance is a good way to cause a few people blood pressure to rise just a hair. Don't create that kind of liability with cells who's track record is less than stellar. Pretty much all "maximum" capacity cells (that's 2500+mAH rated NIMH for AA size) are going to suffer from ever increasing rates of self discharge with use. Anyone who has owned some really bad ones can attest that the self-discharge can get so bad that within 24 hours a cell goes from full to beyond dead, these symptoms can crop up within a few dozen cycles on use on some of these cells, making them not worth a look in a critical application.

At ~2000mAH, Sanyo Eneloops have proven to be absolutely awesome in the reliability department. Their consistency from cell to cell is second to none in the consumer cell market and they will probably outlast any other cell on the market in total useful cycle performance. Being low-self-dischargee cells they will hold near full charge if you have cells sitting for a few days or weeks at a time.

I would also be interested in hearing more about which cells are currently being used. As that may give some kind of indication as to how the eneloops will compared runtime wise, 45 minutes sounds pretty short for a good NIMH cell. On ~1900mAH cells, a 45 minute discharge would mean that the device is drawing around 2.5 amps, I highly doubt that the transmitter is operating at 6 watts. If the device is compatible with alkaline cells then the current draw almost must be less than 0.7A, in which case, good NIMH cells like eneloops would last way over 2 hours.

My GUT tells me that more than likely, the rechargeables you are using are suffering from 1 of several possible conditions:
1. they are NiCD cells and suffer from poor capacity, like ~700mAH. solution: buy eneloops to triple (or better) your runtime.
2. They are NIMH cells of the "high capacity" type, like energizer 2500s, that have already developed massive self-discharge problems, so you are only seeing a fraction of the cells capacity by the time the mic is turned on. Solution: buy eneloops.
3. The charger being used is of poor quality and not properly charging the cells already in use. Solution: buy a better charger, (like the 801D that kirby mentioned, check out other MAHA chargers as well)

 

[tootallll]

Thank you for your replies, they are very helpful.

Attached are specs for the Sennheiser EW 100 G2 transmtter and the BA 2015 Accupack. I do not use the Sennheiser Accupack which holds two 1500mAh NiMH cells but product literature claims that the Accupack will operate the transmitter for 8 hours...under what use and conditions I don't know. I will find out what cells and charger we are currently using...I'm pretty sure the batteries are fairly old. Are Li-Ion cells not recommended?
Thanks!
Mike

 

[SilverFox]

Hello Mike,

Your specification sheet indicates a current draw of around 170 mA. If your batteries were truly 1500 mAh, you could expect around 8 hours from them.

It seems that either your charger is not working properly, or your cells are crap.

I don't know what you need for runtime, but here are some estimates for different cells...

Quality Alkaline - about 6 hours, not rechargeable.
1500 NiMh - about 8 hours.
2000 NiMh - about 10 hours.
2700 NiMh - about 14 hours.
Energizer L91 Lithium - about 20 hours, not rechargeable.

One Li-Ion cell replaces three NiMh cells. Since your application only involves two cells, you can't use Li-Ion unless you want add a voltage reducer to your power pack.

As Eric has mentioned, the Eneloop cells have been rock solid and great performers. I would second a recommendation for those, unless you actually require the additional runtime provided by the higher capacity cells.

In addition, it may be worthwhile to pick up some if the Energizer L91 lithium AA cells to have as a back up. They have a long shelf life.

The Maha C9000 is an excellent charger. It gives you the ability to test your cells to see if any have problems. It also allows you to quickly charge cells if you are in a hurry, or charge slowly when you have more time. You can also do the 16 hour 0.1C charge with it which will improve the long term performance of your cells if you use it periodically.

The problem with the C9000 is that it can only charge 4 cells at a time. With 24 cells, it would take you around 6 hours to get them all charged, depending on the charging rate you choose, and how discharge the cells are.

You may want to send a private message to CPF member Sub_Umbra. I believe he has a similar application and he may have some other ideas to share.

Tom

 

[mdocod]

Tom beat me to it, the magic number "170mA" says it all.

Life is good when you find out that you can probably get 10 hours out of a device you only thought was good for 45 minutes eh? With that kind of runtime, you could probably charge em once a week

Eric

 

[roymail]

Hi Mike and welcome to the forum.

Whatever Eric and Tom advise you to do, you'd be smart to listen. They know about which they speak!

That should be an easy fix.

 

[tootallll]

Wow...thanks everyone, you all have been a been a big help and yes 10 hours should allow me to charge once a week maybe once every two weeks. :thumbsup: I would purchase enough chargers to charge all the cells at once since I wouldn't be able to change them out as they finish charging...can I leave the cells in the charger until I use them?
Mike

 

[Mr Happy]

can I leave the cells in the charger until I use them?

Depends on the charger, but for most chargers, yes.

 

[Robstorch]

The Maha 801D would be the way to go.. charges 8 AA or AAA in 1 hour on fast charge, 2 hours on slow charge and batteries can be left in it until you are ready to use them. I have a new one direct from Maha last week that I will not be needing if you want one at a good price let me know.
Rob

 

[tootallll]

What is the difference between the MAHA MH-C801D and the Maha C9000 chargers besides the ability to charge more cells and a different UI?

I checked the cells we are currently using and they are Energizer 2700mAh recharged by the quick-charger that came with the batteries purchased some time ago at a local Walmart or similar store.

 

[Mr Happy]

I checked the cells we are currently using and they are Energizers being charged by the charger that came with the batteries purchased some time ago at a local Walmart or similar store.

Oh, no...they wouldn't happen to be Energizer 2500 cells, would they? Those cells have gained quite a reputation for under performance and premature failure.

Sadly, when it comes to rechargeable batteries Energizer is not the most reliable brand.

What is the difference between the MAHA MH-C801D and the Maha C9000 chargers besides the ability to charge more cells and a different UI?

The C801D is designed for regular charging duties. The C9000 has many extra features that allow you to measure, test, condition and otherwise obtain the maximum performance from your batteries. For most users it has more features than you will use, so the C801D would be better suited when there are lots of cells to charge.

 

[mdocod]

the reason you are getting 45 minute runtimes on the energizers, is that they have likely self-discharged ~90% of their capacity by the time you actually use them. You mentioned you usually charge them after a performance, this gives them a couple-few days to sit and self-discharge.

The Energizers have been known to develop self-discharge rates so high, that not even a trickle charge will maintain a state of "full" on them. Mine got to the point that they would be dead within ~48 hours of a charge. This rate of self-discharge developed within the first few dozen cycles on the cells. Very disappointing, needless to say, those cells have been retired and now rest in my bag of "some day I'll go dispose of these properly" cells.

 

[tootallll]

Here's the setup up I'd like to purchase...let me know if you think I should do it differently:

6x Sanyo Enelope AA 2000 mAh Ultra Low Discharge NiMH (4 Cell Pack)
2x Maha MH-C9000 Battery Charger
2x Maha MH-C801D Battery Charger

Purchasing the C801D for it's ability to charge twice as many batteries as the C9000 and purchasing the C9000 for it's ability to measure, test, condition...we should get good returns on this investment. I'm glad I found this forum and once again thanks for all your help!
Blessings!
Mike

 

[Aussie Cheese]

you only need 1 801 unless you are looking after a fleet of stuff (24 batteries isnt that many)

Here's the setup up I'd like to purchase...let me know if you think I should do it differently:

6x Sanyo Enelope AA 2000 mAh Ultra Low Discharge NiMH (4 Cell Pack)
2x Maha MH-C9000 Battery Charger
2x Maha MH-C801D Battery Charger

Purchasing the C801D for it's ability to charge twice as many batteries as the C9000 and purchasing the C9000 for it's ability to measure, test, condition...we should get good returns on this investment. I'm glad I found this forum and once again thanks for all your help!
Blessings!
Mike

 

[GarageBoy]

I thought 2700mAh Sanyos were good to go...

 

[Hollow Man]

If you want to push it and get an extra 4-5 hours of runtime, you could do worse than buying good quality 2700 mAh cells. I have the PowerEx ones and they're great performers. If you're going to be recharging every week or two, a good set of regular NiMHs isn't going to discharge that much more in that timespan vs. the Eneloops.

But if there's the chance that you are going to charge less frequently, or you may use the batteries for other applications, then yes, get the Eneloops. They're fantastic.

-HM

 

[tootallll]

It's been almost four years since I made the equipment purchase below and the cells and chargers continue to perform flawlessly...I have saved hundreds if not thousands of $$.

I need to purchase more cells and chargers and thought I'd ask if there were any new products that may perform as well or better than what I have. In our last discussion the 2000mAh Enelopes were chosen over the 2700mAh cells due to reliability. Is this still the case? Any recommendations on new AA cells and chargers?
Thanks!
Mike

Here's the setup up I'd like to purchase...let me know if you think I should do it differently:

6x Sanyo Enelope AA 2000 mAh Ultra Low Discharge NiMH (4 Cell Pack)
2x Maha MH-C9000 Battery Charger
2x Maha MH-C801D Battery Charger

Purchasing the C801D for it's ability to charge twice as many batteries as the C9000 and purchasing the C9000 for it's ability to measure, test, condition...we should get good returns on this investment. I'm glad I found this forum and once again thanks for all your help!
Blessings!
Mike

 

[CKOD]

This thread reads as if it was something modern, if eneloops fit your needs, buy more. If you need more runtime at the expense of self discharge, the eneloop XX's (2500mAh?) would suit, but their cycle lifetime is less than the normal 1900/2000mAh eneloops

 

[aurgathor]

You should check the voltage on several sets of batteries right after they are removed from the wireless mikes. If the volatge on them is over 1.1V or so they are not fully discharged, and the mikes stopped working because of low voltage.
In such a case you could try NiZn batteries -- while their capacity is smaller, whatever they have would be fully used up.