TP 11.1V 3S 2100mah lipo pack

[yongary]

I fully charged the this lipo pack with triton charger/TP balancer. The charger stops charging when it reaches 12.6V. Then, I went to the flying field and did a first hover with my trex 450se. After couple of minutes of hover, I came back home and connected the lipo pack to the triton carger/TP balancer. The display shows it has 11.3V left.

Should I increase my flight time a little bit more? I read lots of posts here and many people suggest to use 80% of lipo pack for safety. That means I can use the lipo pack till it reachs to 10.08V?

I understand that I should not discharge the lipo pack less than 9.0V, otherwise the lipo pack will be dead.

What do you guys think?

My setup is
T-res 450se
Astro flight motor w/ 13T pinoin gear
GWS naro h/bb servos for cyclics and collective
Futaba 401 gyro w/ s9650 tail servo
CC 25amp ESC
JR 790 scanselect rx

[MartinS819]

Yes you can discharge safely to 80% capacity. Just don't go below 3.4v per cell. You should always time your flights. Most Trex flyers time themselves to 5 minutes, but recognize that hovering pulls more amps on the batts than with forward flight. So if you're hovering for 5 minutes, it will draw more power than if you were doing circuits for the same amount of time. Try timing yourself and check the mah you put back into the pack after each flight. Extend each flight by a little bit until you find that you've taken out 80% of the pack capacity and that will be your benchmark time. IMO though, keep it to 5 minutes and no more to help the pack last longer. BTW, this belongs in the "Batteries and Charging section."

-Marty

[RockinRyan]

I fully charged the this lipo pack with triton charger/TP balancer. The charger stops charging when it reaches 12.6V. Then, I went to the flying field and did a first hover with my trex 450se. After couple of minutes of hover, I came back home and connected the lipo pack to the triton carger/TP balancer. The display shows it has 11.3V left.

Should I increase my flight time a little bit more? I read lots of posts here and many people suggest to use 80% of lipo pack for safety. That means I can use the lipo pack till it reachs to 10.08V?

I understand that I should not discharge the lipo pack less than 9.0V, otherwise the lipo pack will be dead.

What do you guys think?

My setup is
T-res 450se
Astro flight motor w/ 13T pinoin gear
GWS naro h/bb servos for cyclics and collective
Futaba 401 gyro w/ s9650 tail servo
CC 25amp ESC
JR 790 scanselect rx
The 80% rule is 80% of the state capacity in mAh not volts. You really should never dischard the pack below the stated voltage at rest - and doing that will almost certainly take you past the 80% capacity! So you do not want to see your pack below 11.1v when measured at rest. You don't have to go as low as 9v to take a considerable amount of life out of your pack.

One thing to understand - resting voltage is not the useable voltage. As soon as you start to draw off the pack the voltage drops to it's nominal voltage. I believe that is from 4.2v down to 3.7v at the start of a fully charged pack. So when you're flying and your pack drops down to the ESC cut-off (which is quite bad) you won't actually read that lowest voltage because the pack will be at rest and the voltage will rise before you get to read it. You need an on-board flight watt meter to really know how low they go in flight...

So to apply the 80% rule take your capacity of 2100mAh and mulitply by 0.8 to get1680mAh. That is pretty much the most that you want to put back when you recharge.

Too much info but I hope it helps. As Martin suggested you can safely find this by timing your flights, watching what you put back and stepping it out. Beware that when you packs reach their safe end point they dump voltage very quickly, so it's not linear necessarily, meaning take smaller additional steps in timing as you near your 80% capacity.

Ryan