how to charge a life pack

[bobby77402]

just purchased a 2100 mah rx 6.6v i use a tritan 2 charger,should i charge on lipo and how many volts,it only gives me 3.7 and 7.7 to chose from,

[kcordell]

Need to use A123 setting for charging if the charger has it. LiFe cells are 3.3v.

[acidla]

Originally Posted by bobby77402

just purchased a 2100 mah rx 6.6v i use a tritan 2 charger,should i charge on lipo and how many volts,it only gives me 3.7 and 7.7 to chose from,

I have a Triton2 and it don't have the option to charge Life packs, you should get a charger that can do Life packs.

[Matt Nasca]

I just got a 1100 mAh, 6.6V 2S LiFe and when I charge it on the LiFe setting it goes from 6.6v to 7.2v in less than a minute and puts in 20 mAh. Then I'll try to discharge it to storage and the voltage drops to 6.6V within a minute and it takes 20 mAh out of the pack...

What's the deal with these?? I've tried 3 chargers and 2 batteries all the same results.

[acidla]

This is normal for Life packs, once they put into operation the voltage drops instantly at 3.3V per cell and stays there for a very long time.

[Matt Nasca]

I changed the discharge cutoff from 3.3v/ cell to 2.7v/ cell and pulled 500 mAh out of the pack. It stayed around 6.4-6.0 while discharging. I wasn't expecting them to be so different from LiPos .

[acidla]

Keep in mind that 6Volts (3V/cell) is the minimum voltage, beyond this point the voltage will drop like a rock and you will not have any control.
You can use up to 70% of the capacity without affecting voltage much.I usually use around 50%.

[Matt Nasca]

Originally Posted by acidla

Keep in mind that 6Volts (3V/cell) is the minimum voltage, beyond this point the voltage will drop like a rock and you will not have any control.
You can use up to 70% of the capacity without affecting voltage much.I usually use around 50%.

I'm actually using the pack as a buffer with my BEC at 7.2V. I just wanted to make sure the battery was working properly before I installed it. Thank you!!!

[acidla]

No worries mate

[MeatRocket]

Originally Posted by acidla

Keep in mind that 6Volts (3V/cell) is the minimum voltage, beyond this point the voltage will drop like a rock and you will not have any control.
You can use up to 70% of the capacity without affecting voltage much.I usually use around 50%.

That's dandy...now how do we tell what 50% is? On a LiPo we judge by voltage, but that doesn't apply linearly to a LiFE. What do we do, measure it in mA that gets applied during charging?

[desertstalker]

Originally Posted by MeatRocket

That's dandy...now how do we tell what 50% is? On a LiPo we judge by voltage, but that doesn't apply linearly to a LiFE. What do we do, measure it in mA that gets applied during charging?

Basically yes, fly a few flights and charge the pack, this will show you how much you use per flight then select number of flights you will fly to get to about 70% used.

[pferg]

I'd just fly one flight how you typically fly at first and recharge. This will give you a good starting point. Load checking is no good with A123. You'll get 6.67 until the battery is almost dead.

[Riff]

I bought a 3s LiFe for my TX and I still do not understand a life and thus I'm afraid to use it inside my TX. Same issues that it will drop from 10,8V really fast and input mAh is small etc.

3,6 x 3 = 10,8 V
3,3 x 3 = 9,9 V
3,0 x 3 = 9 V

When is a LiFe full and when is it empty, at what voltages? What should be the warning voltage level for a LiFe?

Thanks All,
Raimo

[desertstalker]

Originally Posted by Riff

I bought a 3s LiFe for my TX and I still do not understand a life and thus I'm afraid to use it inside my TX. Same issues that it will drop from 10,8V really fast and input mAh is small etc.

3,6 x 3 = 10,8 V
3,3 x 3 = 9,9 V
3,0 x 3 = 9 V

When is a LiFe full and when is it empty, at what voltages? What should be the warning voltage level for a LiFe?

Thanks All,
Raimo

3.6V is full but it will drop almost immediately to ~3.3 where it will stay until it is almost flat. I would set the alarm for 3.2, but be aware that is a charge now value, you may only have 10mins or so left at that point.

IMO the best bet is to charge it after every flight session or few (depends on how much you fly) no reason to let it go almost flat first.

[goraplx]

3.0V per cell is still a lot. The lowest discharge limit is 2.0v.

http://www.multirotorforums.com/showthread.php?t=5669

[desertstalker]

Originally Posted by goraplx

3.0V per cell is still a lot. The lowest discharge limit is 2.0v.

http://www.multirotorforums.com/showthread.php?t=5669

True, but a LiFe cell at 3V is pretty much flat, voltage drops off very fast from that point.