Archive for September, 2009

A123 batteries instead of LiPo

Today I’ve received 3 A123 batteries. Specification of these batteries are unbelievable:

* Nominal voltage: 3.3V
* Nominal capacity: 2.3Ah
* Core cell weight: 70 grams
* Internal impedance: (1kHz AC) 8 mΩ typical
* Typical fast charge current: 10A to 3.6V CCCV
* 70A continuous discharge
* 120A, 10 sec pulse discharge
* Cycle life at 10C discharge, 100% DOD: over 1,000 cycles




The problem is that cell’s nominal voltage is 3.3V, and LiPo has 3.7V. Can we use it instead of LiPo? I had no time to mount these batteries into plane, but I’ve done some testings. First of all I’ve measured my Rhino 2S1P 7.4V Lipo 30C battery with Hextronix 3000 KV motor. Battery was slightly depleted, but motor was running quite ok. Measured current was 9.5A. Then I’ve measured A123 in 2S1P configuration. With same motor, at max rpm. The result was very similar, it was about 9,5A. I’ve connected 3 cells in series and connected to system. Motor was running insanely fast. I couldn’t measure the current, because my multimeter has 10 A limit. I didn’t try max RPMs. I don’t to damage my motor. Few users wrote in forums that they’ve damaged their motor with A123 3S1P configuration. In summary 2 A123 cells can replace somewhat depleted LiPo 7,4V battery :) . With 3 cells you can fly, but you should limit RPMs. When I have results how batteries work in the air, I’ll give you update.
Seems to be all right, just on high RPM engine starts to heat, ESC also.

Pimp my flight – prolonged wings

I’ve decided to prolong wings of the plane by 20 cm each. I was amazed how stable and slow it can fly. Video and few photos.

embedded by Embedded Video

YouTube Direkt