AA batteries

[MikeH]

Anyone who has cracked open a 9V battery has surely noticed it's made up of six 1.5V cells, same as any AA or AAA battery.  I noticed that the capacity of an AA battery is around 2900 mAh, whereas a 9V is only about 625 mAh.  Couple questions: 1) does that mean 6 AA batteries will have a shared capacity of 17,400 mAh (2900x6)?  If so, does that mean that 6 AA batteries will last 25 to 30 times longer than a single 9V?  It would seem other than the physical size they take up, 6 AA batteries would be a better choice.  I must be missing something here- what is it?  Is it just industry standard that keeps everyone using 9 volts?

[R O Tiree]

The individual cells inside a 9V battery are connected in series (voltage is additive) and thus, because the PP9 package is quite small, the individual cells are quite small. The relatively smaller amount of energy (9V * 625mAh) is down to the reduced amount of chemicals/plates/etc that make up each individual cell. The single cell of the AA, on the other hand, has far more volume than a cell in a PP9, so there's more energy able to be stored.

Since you would have to connect the batteries in series, then they are each pushing their 1/6th share of the load and when they've each done 2900mAh -worth, they all die.

So, 6 AA cells in series would provide 9V * 2900mAh, so they'd last a shade over 4.6 times longer than a PP9.

[MikeH]

Interesting- so still worth it if you have the extra room in your enclosure, and the sort of person that uses batteries.

[Mark Hammer]

Why do we all use 9v batteries?  Simple, because it is a good compromise between the most voltage, current. and the most convenient package.

You CAN get 12v batteries in a format that is a tad smaller/shorter than an AA, but the total current capacity is too small to be of use/convenience.

A 6-pack of AA or AAA not only requires more space, but the structure required to keep them in series is costlier and demands more space than a 9v.  That, in turn ups the chassis size requirements, production costs, shipping costs, and storage-space requirements.

As for what is inside 9v batteries, what you find will depend on the type (carbon-zinc vs alkaline) and quality.  Carbon-zinc have 6 stacked "slugs" rather than 6 mini-AAAs spot welded together.  The different interconnection and surface area between has implications for current delivery and the manner in which they respond to suddent current draws at different points in their lifespan.

[Paul Marossy]

Carbon-zinc have 6 stacked "slugs" rather than 6 mini-AAAs spot welded together.

I remember seeing those when I took a 9V battery apart when I was in 5th grade. That was many moons ago. 

[MikeH]

A 6-pack of AA or AAA not only requires more space, but the structure required to keep them in series is costlier and demands more space than a 9v.  That, in turn ups the chassis size requirements, production costs, shipping costs, and storage-space requirements.

Well, sure if you're boss or ibanez, but in terms of DIYing one pedal isn't it possible that the extra few bucks for a slightly larger enclosure and a 6 cell battery holder will save you money in the end, due to the lower expense on batteries (again, if you use batteries - which I do not.  this is all just hypothetical)?

[thereverend]

does it add more mojo if you use d batteries?

i did the math a few years back, basing the cost of 9v batteries for my pedals for a year against the cost of adapters and a power strip. the latter was cheaper. i really dont know why anyone uses batteries in their pedals nowadays since it doesnt seem very convenient or cost effective.

[MikeH]

does it add more mojo if you use d batteries?

i did the math a few years back, basing the cost of 9v batteries for my pedals for a year against the cost of adapters and a power strip. the latter was cheaper. i really dont know why anyone uses batteries in their pedals nowadays since it doesnt seem very convenient or cost effective.

The only time I ever use batteries is in the studio, because it makes my chain quieter.  But yeah, with tha availiability/affordability of power supplies and daisy chains, using batteries is a big waste of money.

[jacobyjd]

The most useful purchase I've EVER made for my rig was my Pedal Power 2.

[Mark Hammer]

There are solutions to almost every problem.  Power blocks are a solution to the problem/challenge of having enough sustainable current.  battery packs are a solution to the problem of noisy power lines.

Just a question out of curiosity:  Do people experience that heterodyning noise issue when powering two or more digital pedals with a common battery pack?

[solderman]

It all comes down to the case and the situation.

How many pedals to power
How many gigs to play
Availability of high power at the stage
A quite setup and ground loop issues
Different pedals need  9, 12 or 18V

To handle most of those situations I have built my self a to step solution. One unregulated wallvart that delivers 12V DC at 1000mA inserted in a regulator that gives me 12V and 9V out. I also have a rechargeable 12V 3,7Ah (I think) motorcycle wet but sealed lead battery if no power is at hand to plug in instead of the wallvart. Lasts for ever.

   
 

[CynicalMan]

Anyone who has cracked open a 9V battery has surely noticed it's made up of six 1.5V cells, same as any AA or AAA battery.  I noticed that the capacity of an AA battery is around 2900 mAh, whereas a 9V is only about 625 mAh.  Couple questions: 1) does that mean 6 AA batteries will have a shared capacity of 17,400 mAh (2900x6)?  If so, does that mean that 6 AA batteries will last 25 to 30 times longer than a single 9V?  It would seem other than the physical size they take up, 6 AA batteries would be a better choice.  I must be missing something here- what is it?  Is it just industry standard that keeps everyone using 9 volts?

I'm pretty sure they are 6 AAAA batteries. They must be better than 6 AAs, there are 12 more As in there!

[trixdropd]

My rechargable aa batteries are 25 mah or whatever the measurement is....

[smallbearelec]

For those who do use them, I have lowered the price of 9V Duracells to $2.00. Duracell U.S.-made AA penlights are $ .50 each.

http://www.smallbearelec.com/Categories.bok?category=Batteries

I forgot to note in my latest Update: 8mm diffused LEDs are now in stock, SKU 2303A, and a suitable black bezel is SKU 0617A. Water-clear high-brightness in this size will be available in a few weeks.

We are growing once again...more parts, more tools, etc.

Regards
SD

[bbmonster]

Anyone who has cracked open a 9V battery has surely noticed it's made up of six 1.5V cells, same as any AA or AAA battery.  I noticed that the capacity of an AA battery is around 2900 mAh, whereas a 9V is only about 625 mAh.  Couple questions: 1) does that mean 6 AA batteries will have a shared capacity of 17,400 mAh (2900x6)?  If so, does that mean that 6 AA batteries will last 25 to 30 times longer than a single 9V?  It would seem other than the physical size they take up, 6 AA batteries would be a better choice.  I must be missing something here- what is it?  Is it just industry standard that keeps everyone using 9 volts?

Got info from http://www.zbattery.com/Connecting-Batteries-in-Series-or-Parallel. In short, series have same capacity while parallel sum the capacity.

From my experience when I raced R/C cars was that you want to match all the batteries in a series connected pack to the same capacity and voltage. Reason being that the stronger batteries would waste their charge recharging the weaker batteries. So basically your pack was as strong as the weakest link.