9V battery question, why?

Not that long ago I bought a CMOY Amp from Ebay to use with my MP3 players. Anyhow when I got/received the AMP the very first battery I put in it was a 9V Panasonic Alkaline, in which lasted for almost 2 weeks and thats with listening to it for over 2 hrs a day. Ok I know that Alkaline has its downside where once it goes fat they are thrown out and cannot be recharged.

A few days later I bought 2 xTrue 9.6V PowerEx which I had already fully charged up as well. But I noticed that this battery only gave me 5days of heavy use. Not that it bothers me as like I said once a Alkaline goes flat, it goes into the bin and more $$$ is spent to buy another one. But if the 9V NiMH batt goes flat it can be recharged.

So really shouldn't a NiMH last longer before going flat.

While a NiMH battery will (should) always last longer in a high drain device (such as a flashlight for example), this may not always be true with a low drain device such as the CMOY you are talking about. The CMOY amp really doesn't draw a lot of current.

When used in a low drain situation, the Alkaline battery may actually have more total power available than a NiMH (I've read that some alkalines AA's may exhibit power equivalent to 2800maH when used very, very slowly). The problem with alkaline is that if you draw a lot of current like in a flashlight, a lot of the power sort of gets wasted and the total power available for use will drop significantly (often closer to 800maH for an AA).

Conversely, a NiMH handles high drain situations better and doesn't seem to lose as much power when used like this, but in a low drain situation may actually have less energy (ex. 2000maH-2700maH for an AA).

Another issue that is probably affecting this is self-discharge. NiMH batteries have a high self-discharge and lose their charge relatively quickly even when they are just sitting there doing nothing. This would also seem to reduce the life considerably in your situation.

So to summarize:
-An alkaline may actually perform better in a VERY low drain device (smoke detector, remote control, ....CMOY)
-NiMH also has high self-discharge which in this case will significantly reduce its life

Also in a nimh 9v battery there are 8 1.2 volt cells as opposed to 6 1.5v cells in an alkaline. This reduces the capacity.

Thanks for your replies. A personal Q here but assume if you had a CMOY amp would you use a NiMH in it or Alkaline. Like I said previously the bonus with a NiMH 9V is that you dont have to go out and keep spending money to get a new 9V Alkaline battery and ok the 9V Alkaline last for 2 weeks where as the 9V Nimh lasted for 1 weeks. I can also fully charge my NiMH batt in a matter of bit over 1 hr.

Albinoni said:

Thanks for your replies. A personal Q here but assume if you had a CMOY amp would you use a NiMH in it or Alkaline.

Click to expand...

Personally I'd hook up 8xAA or 8xAAA low self-discharge NiMH (ex Eneloop or "Duraloop" AA or AAA) in series. But maybe that's just me...

One thing to consider is that NiMh rechargeable 9V cells are the odd ducks in the NiMh rechargeable world - they have significantly lower capacity compared to an alkaline cell.

Those 9.6V PowerEx cells are only 230 mAh cells whereas a 9V primary used in a low current draw situation such as yours would have 660 mAh or more capacity.

Your rechargeable 9V has 1/3 (or less) the capacity of a primary 9V - that's why you are getting less runtime with the rechargeable 9V.

Albinoni said:

A personal Q here but assume if you had a CMOY amp would you use a NiMH in it or Alkaline.

Click to expand...

Even though you get less runtime, you can quickly recharge. You are saving money and it's one less primary cell to be disposed of.

Another lithium 9v question: does anyone make a 9V that's equivalent to three serial CR2 batteries?

Chrontius said:

Another lithium 9v question: does anyone make a 9V that's equivalent to three serial CR2 batteries?

Click to expand...

I know there are LiPo's in a typical 9 Volt package, but I believe they are 8.4 Volt OC.

Dave

Not sure, but I think the primary 9v lithiums use prismatic cells, not cylindrical.

No idea what the rechargable 9v lithium cells use.

Marduke said:

Not sure, but I think the primary 9v lithiums use prismatic cells, not cylindrical.

No idea what the rechargable 9v lithium cells use.

Click to expand...

You may be correct Marduke. Seems like 9 Volt Lithium primaries are hard to find anymore. I used to use them here and there. Expensive, but you didn't have to change them as often, or it seemed that way to me anyway.

I was curious as to where I saw the LiPo 9 volt, so I just looked. It was at TD.

Dave

9V Packs: Alkaline vs Rechargeable; Break Even?

Albinoni said:

...I can also fully charge my NiMH batt in a matter of bit over 1 hr.

Click to expand...

Due to 'Sealed Pack / Series Cells', I've NEVER charged NiCD or NiMH 9Vs at anything more than ~0.1C (DieHard 93558 7-hour Fast Charger @ 15mA; RadioShack 23-428 Universal Ni-Cd/Ni-MH Battery Charger @ 23mA) to avoid overcharging any one cell.

1. What Make/Model Charger are you using to charge in ~1 hour?
   .
2. What is the Charge current?
   .
3. How long have you been using it?
   .
4. What is the mAh Capacity of the 9V packs you've been using?
   .
5. How is it working out for you?

Albinoni said:

...A personal Q here but assume if you had a CMOY amp would you use a NiMH in it or Alkaline...

Click to expand...

• Does the CMOY have a 'Low Voltage Shutdown'?
  - If so, what is it?
  .
• What is the current draw of the CMOY?
  - How much does it vary from the MIN and MAX volume levels that you ordinarily use?
  - Can you estimate the runtime close enough to avoid NEGATIVELY DISCHARGING a cell in the pack?
  .
• *IF* you used a rechargeable pack, how often would you need to charge it?

I'm pretty much with folks like jtr1962 regarding this topic (i.e. Alkaline vs Rechargeable):

jtr1962 said:

...Whenever I come across a battery-powered device which has been sitting idle a while, I know if it doesn't power up then I'll likely find a big mess inside. Sure enough, more than half the time that's the case. It's been such a huge issue for me that I'm phasing alkalines out of my life. As the cells in the few remaining alkaline-powered devices die, they get replaced with Eneloops. I don't care whether or not the economics favor rechargeables (and they may not in something like a wall clock)...

Click to expand...

...since:

1. I have an abundant supply of *CRAP* (i.e. LT 80% Capacity) NiMH non-LSD AA cells.
   .
2. I have an abundant demand for AA cells (remotes, thermometers, etc...) :twothumbs
   .
3. Around a half dozen AA Alkaline devices that I neglected when my health 'went South' a few years back LEAKED and I STILL haven't gotten the initiative / energy to clean them all yet.
   .
4. Last year, IIRC, I found several Rayovac AA Alkalines dated DEC 2011 had *LEAKED* in their package!
   [I've seen 'white crystals' growing out of the ends of NiCDs (i.e. ~20+ year old GEs), but not AAA/AA/C/D NiMHs. I *HAVE* seen 'GREEN crystals' growing out the '-' terminal of TWO DieHard 9V NiMHs (12/2000) to the point that it ATE through the rivet and the connector 'fell off'.]

BUT, the Varta 9V 150mAh NiMhs (12/2002) that I bought for my X-10 Security Consoles (2) and Terraillion Digital Bathroom Scale didn't work out as well as I had anticipated (my pre-CPF days ) - only lasted ~6 years (or ~4 Alkalines worth; 1 x ~$8 vs 4 x ~$2 - BROKE EVEN). This time I'm trying some Harbor Freight 9V 100mAh NiCDs (2) and 160mAh NiMH (1) @ ~$4-5 each, IIRC.

BOTTOM LINE, after all this yakking... IMO, calculate your weekly / monthly / yearly mAh. The better you can do over BREAKING EVEN, the better deal a rechargeable (NiCD or NiMH) cell / pack will be for you.

Black Rose said:

One thing to consider is that NiMh rechargeable 9V cells are the odd ducks in the NiMh rechargeable world - they have significantly lower capacity compared to an alkaline cell.

Those 9.6V PowerEx cells are only 230 mAh cells whereas a 9V primary used in a low current draw situation such as yours would have 660 mAh or more capacity.

Your rechargeable 9V has 1/3 (or less) the capacity of a primary 9V - that's why you are getting less runtime with the rechargeable 9V.


Even though you get less runtime, you can quickly recharge. You are saving money and it's one less primary cell to be disposed of.

Click to expand...

Actually the PoweEx 9.6V I am using is actually a 300 mAh cells, I am really not sure how many mAh cells does the Panasonic Alkaline have in them, doesnt seem to state on the battery.

Re: 9V Packs: Alkaline vs Rechargeable; Break Even?

TakeTheActive said:

Due to 'Sealed Pack / Series Cells', I've NEVER charged NiCD or NiMH 9Vs at anything more than ~0.1C (DieHard 93558 7-hour Fast Charger @ 15mA; RadioShack 23-428 Universal Ni-Cd/Ni-MH Battery Charger @ 23mA) to avoid overcharging any one cell.

1. What Make/Model Charger are you using to charge in ~1 hour?
   .
2. What is the Charge current?
   .
3. How long have you been using it?
   .
4. What is the mAh Capacity of the 9V packs you've been using?
   .
5. How is it working out for you?

• Does the CMOY have a 'Low Voltage Shutdown'?
  - If so, what is it?
  .
• What is the current draw of the CMOY?
  - How much does it vary from the MIN and MAX volume levels that you ordinarily use?
  - Can you estimate the runtime close enough to avoid NEGATIVELY DISCHARGING a cell in the pack?
  .
• *IF* you used a rechargeable pack, how often would you need to charge it?

I'm pretty much with folks like jtr1962 regarding this topic (i.e. Alkaline vs Rechargeable):

...since:

1. I have an abundant supply of *CRAP* (i.e. LT 80% Capacity) NiMH non-LSD AA cells.
   .
2. I have an abundant demand for AA cells (remotes, thermometers, etc...) :twothumbs
   .
3. Around a half dozen AA Alkaline devices that I neglected when my health 'went South' a few years back LEAKED and I STILL haven't gotten the initiative / energy to clean them all yet.
   .
4. Last year, IIRC, I found several Rayovac AA Alkalines dated DEC 2011 had *LEAKED* in their package!
   [I've seen 'white crystals' growing out of the ends of NiCDs (i.e. ~20+ year old GEs), but not AAA/AA/C/D NiMHs. I *HAVE* seen 'GREEN crystals' growing out the '-' terminal of TWO DieHard 9V NiMHs (12/2000) to the point that it ATE through the rivet and the connector 'fell off'.]

BUT, the Varta 9V 150mAh NiMhs (12/2002) that I bought for my X-10 Security Consoles (2) and Terraillion Digital Bathroom Scale didn't work out as well as I had anticipated (my pre-CPF days ) - only lasted ~6 years (or ~4 Alkalines worth; 1 x ~$8 vs 4 x ~$2 - BROKE EVEN). This time I'm trying some Harbor Freight 9V 100mAh NiCDs (2) and 160mAh NiMH (1) @ ~$4-5 each, IIRC.

BOTTOM LINE, after all this yakking... IMO, calculate your weekly / monthly / yearly mAh. The better you can do over BREAKING EVEN, the better deal a rechargeable (NiCD or NiMH) cell / pack will be for you.

Click to expand...

Hi I wil do my best to answer your questions here.

1. The charger that I am using is this one:

http://servaas.com.au/maha-powerex-c490f-9v-4bank-charger-3x9v-batteries-p-36.html

That 1 hr is just a made up time figure from me, because apparently this charger can charge 4 9V's in 2 hrs, so I am assuming it would charge 1 300mAh in 1hr.

2. I honestly dont know and would have to find out?
3. Approx 2 weeks or close to (its brand new).
4. I have 2x9.6V batts and each is 300 mAh.
5. It works out as I dont ahave to go out everytime and buy a new 9V batt
in which saves me time and money, though I was tempted to buy a box
of 12 9V Procells (Duracell) off Ebay. While the Alkaline might give me
approx 12 days run time, the NiMH gives me about 6.

6. What do you mean by shutdown? No the CMOY doesnt turn it off by
itself after say 5 mins like what a calculator or MP3 player does.

7. I will have to charge at least probably onece a week this is with my NiMH

Also I forgot to add. I have approx 8 MP3 players (Cretive Zens, Cowons and Sansa Fuze. The Zens are powerful and have quite a loud/high Vol level output, I bought a black 8GB Sansa Fuze recently and though its a lovely player with very nice sound quality, I have found the Vol to be slightly weaker to that of the Zens. This means that I have to turn up the Vol level slightly more on both the Fuze itself and the CMOY amp, where as if I have the Zen Vision M or my other Creative Zens connected to the CMOY I dont need to turn up the Vol level of the CMOY as the output level already on the Zen is quite loud.

The C490F says it has a charge current of 70-90 mA. If we take 80 mA as a round number, a 300 mAh battery is likely to take about 4 hours to charge. That would be the same for one battery or four, since it's 80 mA per channel.

Mr Happy said:

The C490F says it has a charge current of 70-90 mA. If we take 80 mA as a round number, a 300 mAh battery is likely to take about 4 hours to charge. That would be the same for one battery or four, since it's 80 mA per channel.

Click to expand...

But I thought the charger can charge up to 4 9V batts in a matter of 2 hrs according to the website.

The batt did fully charge because the LED light on the charger went green.

Hello.

I charge my 9Volts BTY 280mAh cells @200mA, sometimes @300mA.
They where bought from DX $6.41 so i don't care if I charge them too hard.


Charger used is Bantam BC-6
They never got warm.

I discharged them earlier on CBAII, can't find the file but they where under 200mAh if I recon right.

Anders