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View Full Version : difference in battary weight between 1500 and 2300 NiMH


sigepkev
12-19-2005, 06:26 AM
What are the weights of an average AA size NiMH at 1500, and say 2000 or 2300 mah.

I did a test run through on a fresh pack with 9.6v 1400 mah and only got mabey4 min. in the charge. I really would like a little longer flight time, but this is being used in an easy glider electric and do not want to weigh it down too much.

Red Scholefield
12-19-2005, 03:02 PM
What are the weights of an average AA size NiMH at 1500, and say 2000 or 2300 mah.

I did a test run through on a fresh pack with 9.6v 1400 mah and only got mabey4 min. in the charge. I really would like a little longer flight time, but this is being used in an easy glider electric and do not want to weigh it down too much.

Try the manufacturers spec sheets, they give weights for various cells.

http://sanyo.wslogic.com/

rcnerd
12-19-2005, 06:52 PM
Also the high capacity aa cells aren't great for a flight pack....the extra mahs are wasted as heat. The easy glider is speed 400? If so you should get 5-10 min on 700 mah nicads!!!

Matt Kirsch
12-19-2005, 08:44 PM
Yes, there's more to it than just mAh. A cell's internal resistance actually has more to do with how well it performs, and how efficient it is, than the raw capacity.

Take a NiMH AA cell. As you pack more and more of that electrical "stuff" in there to increase its capacity, you also increase its internal resistance. The cell's discharge capability decreases; it performs worse on heavy loads than the lower-capacity cell.

You're already seeing this now with your 1500mAh cells. It will only be worse if you go to 2300mAh cells because these cells have a much higher internal resistance. They're meant for low-current loads like digital cameras and kids' toys, not flight packs.

If you swap out your AA packs for packs made from shorter, fatter 2/3A cells such as the CBP1150s, KAN1100s, or Intellect1200s at www.cheapbatterypacks.com (http://www.cheapbatterypacks.com), you'll see much higher performance and much longer flights, with little to no additional weight, even though the battery packs don't have half the capacity of your 2300mAh AAs. This is because the shorter, fatter 2/3A cells have a much lower internal resistance, and make excellent flight packs.

...and here's my dreaded clown car analogy: The cell with high internal resistance is like a tiny clown car with 16 clowns packed in it. The cell with low internal resistance is like a city bus with 16 clowns sitting in relative comfort. Now, have one of the clowns scream, "FIRE!" The clowns in the clown car will thrash and smash each other. Much cussing and swearing will ensue, and some of the clowns will probably die in the process, while the clowns in the city bus file off in an orderly fashion. That's how it is inside the batteries.

rcnerd
12-19-2005, 09:02 PM
LOL nice analogy.....so wher can I get those clown car packs?

kuzikood
12-19-2005, 11:44 PM
roflmao i hate clowns .

-kuzi-

sigepkev
12-19-2005, 11:55 PM
well, thanks.

I think this explans what I have seen. I bought a fire bird freedom as a gift and it has a 480 motor in it with a 1100 mah pack, I think 2/3a and it last a really long timme compared to my 400 size on a 1400mah aa pack.

Thanks

kuzikood
12-20-2005, 12:11 AM
no really i hate clowns lol

-kuzi-