What's all the hype with Lipo over AA NiMH?

[dima]

I know I may sound retarded (I am new in electric RC) but what exactly are the advantages of these expensive LiPo batteries and NiMH battery packs compared to AA NiMH. LiPos and the 2/3 packs are like 1500Mah tops? Whereas AA NiMh are 2500Mah. Why is everyone going LiPo route? Is there longer runtimes there? I thought runtime depends on Mah value only?

With AA you can use smart charger, charge individual cell and if one cell dies you don't need to throw away the pack. 6 AA NiMH of 2500Mah cost like $12 only!

Is there anything I am missing or misunderstanding? What's all the hype about expensive but low capacity battery packs?

[Lord_Inferno]

The main difference with the lipo is that they have much better discharge rates for faster motors.

The difference between AA batteries and NIMH is that AA batteries don't have as good discharge rates either.

If u run say the 1400mah 9.6v batteries they will go much better than the standard AA 7.2 volt.

I made this little invention though


9.6 volt AA battery packs
It works quite well, but the acceleration still isn't as good as the 9.6 volt NIMH packs

http://miniinferno.zexxo.net/howto/8cellAA.html

[dima]

The main difference with the lipo is that they have much better discharge rates for faster motors.

The difference between AA batteries and NIMH is that AA batteries don't have as good discharge rates either.

If u run say the 1400mah 9.6v batteries they will go much better than the standard AA 7.2 volt.

I made this little invention though


9.6 volt AA battery packs
It works quite well, but the acceleration still isn't as good as the 9.6 volt NIMH packs

http://miniinferno.zexxo.net/howto/8cellAA.html

Very nice instructions, thanks bro!

[Number_8]

You also forgot that LiPo's do have a longer runtime, I have a 7.4v LiPo 1800 Mah, and goes for an hour. Only problem with LiPo's is that they can be quite dangerous if not treated properly, and if you run them too long without a cut-off voltage you will not be able to re charge it.

[Lord_Inferno]

Thats ok dima,
I have quite a few more articles off my site that i'm writing up.
But they take time

[Jshwaa]

I know I may sound retarded (I am new in electric RC) but what exactly are the advantages of these expensive LiPo batteries and NiMH battery packs compared to AA NiMH. LiPos and the 2/3 packs are like 1500Mah tops? Whereas AA NiMh are 2500Mah. Why is everyone going LiPo route? Is there longer runtimes there? I thought runtime depends on Mah value only?

It's about power density. The discharge rate of polymers is so much higher per volume of material, you can pack more punch for the amount of space you use for cells. The geometry of lipos helps as well. Most, if not all, lipos are a rectangular block, which makes for stacks that can neatly pack in a rectangular space, whereas a cylindrical wastes a little bit of volume in between each cell, as the only part that mates with the next cell is a fine line of the outside of the cylinder. All that other surface area of the cell is surrounded by AIR, which is a waste and very well could be the exploit of your racing opponents. You use lipo to maximize that part of your system, so that you don't have to worry about power supply anymore. You can maximize your ESC and motor, knowing that you're doing all you can to provide it with adequate power.