What is the difference between 1 AA, and 4 AA's wired in parallel?

Is the longer run time the only difference at all.

For this circuit do you think I could run 4 AA's in series?

Someone mentioned that it runs nice off of 2 AA's, I want my light to use 4 AA's, so do you think I should wire two batteries in parallel, then wire the packs together in series with this circuit? or would that not even work for some unknown reason to me.-'

It will not work with 4 AAs in series. Too much voltage. 2 parallel and two of those in series should work.

Oops, I didn't mean 4 in series, I meant to write, 4 wired in parallel.

I am wondering what all happens when you wire batteries in parallel other than it increasing run time.

For instance, could you wire 8 AA's in parallel to that circuit, or is there something I don't know about wiring lots of batteries up in parallel that I don't know about?

Cavelightchris said:

Oops, I didn't mean 4 in series, I meant to write, 4 wired in parallel.

I am wondering what all happens when you wire batteries in parallel other than it increasing run time.

For instance, could you wire 8 AA's in parallel to that circuit, or is there something I don't know about wiring lots of batteries up in parallel that I don't know about?

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Nothing bad will happen. The driver will only draw what it needs.

Thanx for your help you guys, I have been dying to know if you could do that.

So now I am going to assume, that if this circuit can run off 1.5 volt AA's, that you could always change that to 1.5 volt C or D batteries?

Cavelightchris said:

Thanx for your help you guys, I have been dying to know if you could do that.

So now I am going to assume, that if this circuit can run off 1.5 volt AA's, that you could always change that to 1.5 volt C or D batteries?

Click to expand...

A 1.5V D battery will behave similarly to 4AAs in parallel.

In addition to having more capacity, using a higher capacity cell, or multiple cells in parallel, will give you lower internal resistance. Internal resistance causes the voltage of the cell to drop under load, which forces the driver to pull more current to compensate. Lower internal resistance means less energy loss, so 4AAs in parallel should actually run MORE than 4x longer than 1AA.

That's not the only factor however. The greater the voltage gain required in the boost driver, the less efficient it will be. That means a 2series 2parallel configuration will be more efficient than a 4paralell, since stepping up from 2.4v (2 alkaline cells under load) to 3.6v is less of a boost than going from 1.2v to 3.6v.

If you have a light that can fit 4AAs however, I wouldn't recommend that driver at all. I'd suggest using all four AAs in series, with a buck, or voltage step-down drivers like this. Buck converters are generally more efficient than boost converters like the one you linked to.

That is so funny you linked to that, I was just reading all the replies for it for the last 10 minutes now.

Thanx a million, I really do want the most efficient setup, so thanx for pointing it out to me, I wasn't sure of anything. Do you know what the most efficient setup is using AA's, it sounds like 4 AA's is good, but your holding out on me and there's something better right? I wonder.-'

Are you serious that 1.5 volt alkaline's are only 1.2 volts under load, I did not know that. This really confuses me, then why do they even bother calling it a 1.5 volt, is it because their 1.5 volts if you tested one without any load right, I think I got it.-'

I have been dying to know what 1.7 volt lithiums are under load?????

It seems like from what I read 1.2 volt NIMH batteries are slightly above 1.2 volts fully charged, but I still wasn't positive if they are the same under load?

I just had an epiphany, so would this be the most efficient setup for the board you suggested:

Wire up 2 packs in parallel, 4 AA's in series in each pack. Would that make things more efficient?



I am guessing that if I use 5 AA's the Q5 LED will be driven hard enough that it will become less efficient. I also realize that if you only use 3 AA's in series, that the light will shut off before the batteries even get to use all their juice.
So wouldn't it appear that 4 AA's in series is the most efficient way to go here.

Also wondering, does anyone know what voltage a lithium AA is when it's run all the way down. I would like to know that for NIMH, and Alk as well if anyone knows.-'

Thanx ahead of time,

Chris

2 stacks of 4 AAs in series would work with the driver.

NiMh and Lithium batteries have much less internal resistance then an alkaline battery so their voltage(and capacity) will sag much less. An alkaline battery would be fine for low draw applications but for anything involving most high power LEDs, lithium or rechargeable would be the best choice.

You might want to try some of the battery testing thread for voltage and capacity info,=.

You will likely find answers to all your questions about batteries in this forum : http://www.candlepowerforums.com/vb/forumdisplay.php?f=9