AAA vs AA help

[Marcos]

I have 2 choices of battery sizes but I need to stay light and yet have performance,a 7 Cell AA or AAA Nicad pack to turn the electric motor. One pack the AA size is rated at 600mah and the AAA pack [smaller in size is rated higher at 700mah ,Which [pack] will give me the best performance and duration in flight?

[Dave Hederich]

Your 700mAh AAA pack is not NiCd, it is NiMH. There are no AAA NiCd cells that provide 700mAh. Whether the AAA pack will work or not depends on the current that your motor is drawing. Generally speaking, if you have a Speed 300 or larger motor in direct drive, the motor will draw more current than AAA NiMH cells can deliver.

[Marcos]

Respectfuly ,thanks for the information on the AAA cells , Do I need the AE cells with my speed 400 to function properly??????

[vintage1]

My tentative research and a bit of practical investigation shows that the 600 AE cell is a dmaned good allrounder. You can easily do the 10A that a sp400 likes, and in fact 15A or more is reasonable.

Another good choice is 800AR for 'hot' model where the lower resistance and slighly fatter energy rating gives direct drive screamers an edge.

The other 'normal' cell in this range is uaually the 1100mA/h or 1300NimH. Usual;ly 'one cell more' to allow for greater internal resistance than the AE's pr AR's

An interesting alternative is 1100AAU, which will give good duration as long as currents are kept down below 15A and you can cary the weight..

I seem to be building a lot of models in this class, and what I am using and intend to use are..

...lightweight models for slow flying (not slo flyers, just old fashioned planes) i am using 7 or 8 600AE's. These will also do for lightweigh fatser models but for
... direct drive speed 400 warbirds and picojets, 8x800AR or possibly if you don't mind teh wing loading, the 1300Nicds. Or perhaps 8x1300NiMh for slightly less zoom, anmd a bit more duration.

...larger models with 400/480- geared motors - 10x1100AAU allows a lot of efficiency and power, but not outright screamability.
I need to ultimately get a new pack for the picojet - and am torn between 800AR and 1300Nimh...

[Dave Hederich]

Vintage1 gave you a lot of good advice on specific cells. I'll just say, in a general sense, when you ask which is the best cell for performance AND duration in flight, you are really asking for two different packs. The best performance pack generally contains NiCd cells designed to deliver power quickly and easily, which means they are not going to have the best duration. A NiMH pack is better than a NiCd pack of the same size for flight duration, but generally will not deliver power as quickly and easily. So if you want to fly intense, high-speed aerobatics, go with a high-performance NiCd pack. If you want longer, more leisurely flights, go with a NiMH pack. The better NiMH AA cells (~1600mAh) will handle up to a direct drive Speed 400. I just bought a bunch of Panasonic AA NiMH cells at Odd Lots for $4.99 per 4-cell package.

[Marcos]

say thanks for the footwork you have done, can I get the AE cells rated at 700 or 800 mah? and the1300Nicds. you mentioned are they AE ,AR or sub c ?

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[steve lewin]

Please take some time to read the EFlight FAQ (link at top of page), particularly the battery section. Among other things, that should give you some idea of what the various battery codes mean. E.g. AE is a specific cell type, sub-C is just a size.

It's only the 600AE that is a good battery not any other capacity that happens to have AE in the code. The 1300NiMH cells are usually AA sized.

Steve

[Gary Retterbush]

I have recently been using 7 pushed and matched GP 1000's for my S400 and I'm very pleased with them so far. My motor time has almost doubled over the Sanyo 600AE's I normally use in this plane. I just have to remember to not let them get cold!

[Marcos]

The only reason I don't use nimh is that my chargers are all for NiCads, and If I do purchase a fast charge unit for nimh,how long will say a 7 cell 1300mah pack take to charge?

[Dave Hederich]

I charge my 720mAh AAA NiMH cells at 2C (~1.4A). I'm not sure what the AA NiMH cells will take. If C, then they'd charge in 60 minutes; if 2C, in 30 minutes; if 3C, in 20 minutes.

[Marcos]

Originally posted by Dave Hederich
I charge my 720mAh AAA NiMH cells at 2C (~1.4A). I'm not sure what the AA NiMH cells will take. If C, then they'd charge in 60 minutes; if 2C, in 30 minutes; if 3C, in 20 minutes. ===========================================
Can you safely charge an AA or a AAA pack at 3C[ Nimh thast is]

[steve lewin]

I'd say no. I don't even go as high as 2C if I can avoid it though some people seem to get away with it. The couple of times I've tried it they got way too hot.

Steve

[Marcos]

Originally posted by steve lewin
I'd say no. I don't even go as high as 2C if I can avoid it though some people seem to get away with it. The couple of times I've tried it they got way too hot.

Steve ========================================

Thats a logical Answer Thanks for clearing this up. :p