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Old Dec 09, 2012, 07:40 AM
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United States, IL, Chicago
Joined Aug 2003
17 Posts
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UltraMicro battery life - When do you declare them dead?

I've been flying my Eflite UM, and Blade micro heli's for a year or so now. (I think...) And I've been enjoying them immensely.

I've noticed my flight times dropping. So I decided to break out my nice charger, and test the batteries to see what they're really giving me.

Before anyone jumps at me, I didn't do this "right." I don't have time to gently cycle each cell properly. But what I've done should give a really good idea of what's going on.

Here's how I did it. I used my 6 way adapter, and discharged all of my batteries down to 3v at less than 1c per cell.

I then have been charging all of my cells at 200ma. Since there are losses while charging, my charge numbers will be "generous."

Here are my results:

Code:
No Brand       Label  Test   C    Heli/Plane
1  Eflite      150ma  154ma  12c  Plane
2  Venom       120ma   94ma  25c  Heli
3  Eflite      150ma   83ma  12c  Heli
4  Eflite      150ma  134ma  12c  Plane
5  Eflite      120ma  108ma  14c  Plane
6  Eflite      120ma   79ma  14c  Heli
7  Eflite      120ma  103ma  14c  Plane
8  Eflite      120ma  100ma  14c  Plane
9  Eflite      120ma   72ma  14c  Heli
10 Eflite      120ma  106ma  14c  Plane
11 Eflite      120ma   94ma  14c  Heli
12 Turnigy     160ma  145ma  40c  Heli
13 Turnigy     160ma  145ma  40c  Plane
14 Eflite(25c) 150ma  153ma  25c  Heli
15 Turnigy     160ma  130ma  40c  Heli
16 Turnigy     160ma  136ma  40c  Plane 
17 Turnigy     160ma         40c  Plane
18 ParkZone     70ma
19 ParkZone     70ma
20 Eflite(25c) 150ma         25c  
21 Eflite(25c) 150ma         25c
Anything with velcro on it, got most of it's use in planes. Anything without velcro on it never saw use in planes. I think there's a direct correlation to C rating and battery life.

To cut to the chase, at what capacity do you declare a battery dead? The industry at large considers 50%. I'm thinking about this, and as the batteries lose capacity, i'm effectively running them at higher C ratings. That can't be good.
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Last edited by nerobro; Dec 09, 2012 at 07:49 AM.
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Old Dec 09, 2012, 09:24 AM
Registered User
United States, IL, Chicago
Joined Aug 2003
17 Posts
Hmm. Took 4 cells with me to the field this morning. I found batteries 1 and 4 couldn't sustain full throttle for more than 5 seconds before things started flashing.

Those are getting retired. 13 and 16 were just fine, and could go minutes.

I wonder if I'll have more than 5 good batteries at the end of my testing. :-) At least I'll have cells where I can be confident in flight time.
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