int2str
03-20-2008, 08:06 PM
Alright...
I have two Cellpro Revolution 2100mAh and my trusty old E-Flite 1800mAh that came with the Blade 400. I figured I'd ride the 1800 pack like crazy and it would probably be the first to go. I charge it at 4A right after flying, fly it exactly as long as my 2100mAh packs (even so it has less capacity) etc.
However, today I may have accidentally killed a 2100mAh pack...
I've been flying based on my TX timer set at 5:30min. That usually leaves around 3.75V in the packs and I put back about 1500mAh into the 2100mAh pack. I'd say that's going easy on the batteries, no? They have many many cycles now and balance perfectly with my CellPro 4S charger.
Today I did not forget to set my timer, I forgot to reset it. So instead of counting down from 5:30. It continued counting UP from about 0:30sec where I left it from my previous flight. So I'm flying pretty hard in very strong winds and hear the minute beep every once in a while ensuring me that indeed, my timer is running.
After a while power started to drop and the motor started pulsing (low voltage cut-off on the ESC). Landed instantly with a low altitude auto and looked at the TX... Timer was at 8:40min.... I had flown > 8min in strong winds, straining the heli quite a bit at times.
The pack was much warmer than usual. After 5:30min the packs are barely luke warm. This one was almost hot, though I could comfortably hold it in my hands still. There is no visual deformation or bulging.
I rushed the battery to the charger and it showed a noticeable cell imbalance at that point (1 cell mainly). Cell voltages were 3.36V, 3.32V and 3.2V. It seemed to charge normally and balanced ok to 4.19Vx3.
If it was 3.2V at rest right off the heli, I'm sure it dropped below 3V under load.... I had to approach with low voltage cut-off on already against heavy wind to get it to the landing area....
Sooooooooo.... how bad is it, doc?! :(
I have two Cellpro Revolution 2100mAh and my trusty old E-Flite 1800mAh that came with the Blade 400. I figured I'd ride the 1800 pack like crazy and it would probably be the first to go. I charge it at 4A right after flying, fly it exactly as long as my 2100mAh packs (even so it has less capacity) etc.
However, today I may have accidentally killed a 2100mAh pack...
I've been flying based on my TX timer set at 5:30min. That usually leaves around 3.75V in the packs and I put back about 1500mAh into the 2100mAh pack. I'd say that's going easy on the batteries, no? They have many many cycles now and balance perfectly with my CellPro 4S charger.
Today I did not forget to set my timer, I forgot to reset it. So instead of counting down from 5:30. It continued counting UP from about 0:30sec where I left it from my previous flight. So I'm flying pretty hard in very strong winds and hear the minute beep every once in a while ensuring me that indeed, my timer is running.
After a while power started to drop and the motor started pulsing (low voltage cut-off on the ESC). Landed instantly with a low altitude auto and looked at the TX... Timer was at 8:40min.... I had flown > 8min in strong winds, straining the heli quite a bit at times.
The pack was much warmer than usual. After 5:30min the packs are barely luke warm. This one was almost hot, though I could comfortably hold it in my hands still. There is no visual deformation or bulging.
I rushed the battery to the charger and it showed a noticeable cell imbalance at that point (1 cell mainly). Cell voltages were 3.36V, 3.32V and 3.2V. It seemed to charge normally and balanced ok to 4.19Vx3.
If it was 3.2V at rest right off the heli, I'm sure it dropped below 3V under load.... I had to approach with low voltage cut-off on already against heavy wind to get it to the landing area....
Sooooooooo.... how bad is it, doc?! :(