NiMH - How Much mAh Is Enough?

[vranswer]

I'd like to use rechargeable batteries in my amp, and was wondering what opinions are as to type of NiMH battery. Is there any benefit from higher and higher mAH ratings, or will it be enough to just get the Energizer rechargeables from a local store? The department store batteries are rated at 750 mAH, but I can get up to 2000 mAh or more online. Is it just a matter of how long they'll last before needing recharge (and how long it takes to charge)?

About how long does it take, for example, to charge a 750 mAH battery and how long would it run before needing a charge? And do these 2100 mAh batteries like Maha, etc. take exceedingly long to charge..like 24 hours or something, to the point of absurdity?

 

[go_vtec]

Are you talking about AAs, AAAs or 9V?

Hmm, it sounds like AAs based on the specs (2000-2100mA)! If you are talking about AAs, it can be charged in an hour upto 1000 times (expect 500-800 charges or 3-5 years of service life). Usage of the batteries are heavily depend on the system... but expect approximately 40-80 hours of operation time for 4 AA powered amps.

 

[Eagle_Driver]

Quote:

Originally Posted by vranswer I'd like to use rechargeable batteries in my amp, and was wondering what opinions are as to type of NiMH battery. Is there any benefit from higher and higher mAH ratings, or will it be enough to just get the Energizer rechargeables from a local store? The department store batteries are rated at 750 mAH, but I can get up to 2000 mAh or more online. Is it just a matter of how long they'll last before needing recharge (and how long it takes to charge)? About how long does it take, for example, to charge a 750 mAH battery and how long would it run before needing a charge? And do these 2100 mAh batteries like Maha, etc. take exceedingly long to charge..like 24 hours or something, to the point of absurdity?

Actually, the higher-capacity batteries are much, much larger than their lower-capacity brandmates. Don't assume that every rechargeable NiMH battery fits into every device. They come in a hodgepodge of completely different sizes and shapes.

First off, neither the AA nor the AAA batteries will fit the SuperDual amp of yours at all - it will accept only a single rectangular 9V battery. And as far as I know, there is no current rechargeable "9V"-size battery rated at higher than about 220 mAh. Worse, most department-store "9V"-size NiMH batteries deliver only 7.2V or 8.4V, and their capacity tends to be a conservative 150 mAh. In your particular case, then, throwaway alkaline 9V batteries (typically rated at 500 to 600 mAh) are the only way to go with your particular amp (if you cannot order batteries online).

 

[crazyfrenchman27]

Quote:

Originally Posted by vranswer The department store batteries are rated at 750 mAH, but I can get up to 2000 mAh or more online. Is it just a matter of how long they'll last before needing recharge (and how long it takes to charge)?

I believe that this is the case. I do not believe that it will affect the sonic characteristics of your amplifier.

750 mAH is rougly the size of the third-generation lithium ipod battery. It lasts for about eight to ten hours in an ipod.

2000-2100 mAH lithium last for about twenty hours in an ipod.

How that equate to battery life-time in your amplifier...I have no idea.

They both charge in about four hours...I don't know how fast NiMH charges.

I just replaced my third-generation ipod battery last week with an 850 mAH, which is why I know all this useless information.

Currently Listening to: Daft Punk's "Like A Prayer" mix of Madonna.

 

[vranswer]

Yes, I should specify that I'm referring to AAA batteries which are used in the new SuperMono that is currently hurtling my way at the speed of the USPS. I was not aware of the different physical sizes issue, but is that also the case for AAA's?

 

[Illah]

If you can get four AA 2000mAh batts in an amp it will last a LONG TIME. Most PDA's, Cell phones, iPods (based on what guy said above

), have less than 1000mAh of power. With 8000mAh you'd be good for weeks.

One problem I've noticed with NiMH batts is the power 'leaks'. This won't damage your equipment or anything, but if you don't use them or charge them for a while they will slowly lose charge.

--Illah

 

[Eagle_Driver]

Quote:

Originally Posted by vranswer Yes, I should specify that I'm referring to AAA batteries which are used in the new SuperMono that is currently hurtling my way at the speed of the USPS. I was not aware of the different physical sizes issue, but is that also the case for AAA's?

Oh, in your Supermono, then, the highest capacity AAA NiMH rechargeables on the market are rated at about 850 mAh. (Contrast that to the typical AAA alkaline's capacity rating of about 1000~1200 mAh, and you'll see why rechargeable AAAs are a better bet for that particular amp.)

 

[kiwirugby]

vranswer,

I just bought 8 "AccuPower" NiMH AAAs from Thomas Distributing for exactly the same purpose as you: the SM that is flying down Insterstate 5 to me here in souther California.

The specs read (going blind trying read it!!!): 1.2 Volt, up to 1000mAh. Mine are charged and ready to go.

Not sure is this helps, but I thought I would pass it along

 

[guppi]

You wont find AAA rechargeables (much) above 1000mAh. The 2200mAh batteries you are seeing are AAs. Within AAA batteries there are no size differences. The runtime you will get out of them should be pretty much linear in the mAh rating. The charging time will depend on the charger you are using.

 

[Illah]

Quote:

Originally Posted by guppi You wont find AAA rechargeables (much) above 1000mAh. The 2200mAh batteries you are seeing are AAs. Within AAA batteries there are no size differences. The runtime you will get out of them should be pretty much linear in the mAh rating. The charging time will depend on the charger you are using.

Yeah, read up on chargers. My Lenmar (I think that's the name...) is a VERY highly rated charger that can fully charge a 2000mAh+ AA in an hour! Cheap eBay $10 chargers can take up to 12-18 hours which is unacceptable to me - spend the extra $30 for a good one. I've partial charged AA's for 20 mins with my digicam and had enough juice to get plenty of shots.

--Illah

 

[Eagle_Driver]

Actually, Illah, it is impossible to fit any batteries inside an amp other than the single size that the battery compartment is designed to hold. As I said, the Supermono is designed strictly for AAA-size batteries - and AA batteries will not fit inside at all. (At least not without severe modifications.)

 

[go_vtec]

Quote:

Originally Posted by vranswer Yes, I should specify that I'm referring to AAA batteries which are used in the new SuperMono that is currently hurtling my way at the speed of the USPS. I was not aware of the different physical sizes issue, but is that also the case for AAA's?

For AAAs, you will be looking at around 700-800mAh rated NiMH batteries. I'm using four Energizer NiMh AAAs with my Total AirHead (rated 750mAh) and they last me roughly 40-80 hours. It should last approximately the same on your amp, and AAAs charge much faster than AAs (less than an hour).

 

[vranswer]

Quote:

Originally Posted by go_vtec For AAAs, you will be looking at around 700-800mAh rated NiMH batteries. I'm using four Energizer NiMh AAAs with my Total AirHead (rated 750mAh) and they last me roughly 40-80 hours. It should last approximately the same on your amp, and AAAs charge much faster than AAs (less than an hour).

OK thank you, now brings up another question. The SM can hold EIGHT AAA batteries, but can run on as few as four (if I understand correctly). Does anyone think there would be any benefit from popping all eight in there. Four obviously is lighter on the belt.

 

[Dixie Flatline]

Quote:

Originally Posted by vranswer Yes, I should specify that I'm referring to AAA batteries which are used in the new SuperMono that is currently hurtling my way at the speed of the USPS. I was not aware of the different physical sizes issue, but is that also the case for AAA's?

Also, just to inject a note of paranoia -- you may want to verify with Xin that whatever batteries you buy will work with the amp, particularly WRT the voltage level. Bobjew, who had one of the Superdual prototypes, said that he managed to fry it by putting a 9.6V Plainview rechargeable in it. (The SD is designed to use the Energizer 9V rechargeable, which is actually only 7.2V.)

So I'd just check with Xin and make sure you're not going to fry the amp when you put the batteries in it...

 

[Daroid]

Quote:

Originally Posted by vranswer OK thank you, now brings up another question. The SM can hold EIGHT AAA batteries, but can run on as few as four (if I understand correctly). Does anyone think there would be any benefit from popping all eight in there. Four obviously is lighter on the belt.

It might be convenient if you're on a trip for a weekend or so without access to a charger. Your choice, else there is no benefit in it.

The 750 mAh you saw could have been NiCD cells instead og NiMHs, if you're saying that both types were size AA. NiCD can be convenient if you're using it in frosty weather with low temperatures, since NiMHs die out very quickly at the same low temperatures. AFAIK NiCDs can't be charged very fast like NiMHs and they polute the environment badly if correct disposal wasn't done.