When is a battery considered to low to fly?

[colchester daz]

I currently have my controller go made at me when the battery reaches 10.8v.

Does anyone run their battery lower? Ive read as long as you dont drop more than 3v per cell you wont damage the battery.

Just wondered what everyone else does.

 

[MRSpyder2U]

This guy is a guru on batteries in general and LiPo in particular. http://www.rchelicopterfun.com/rc-lipo-batteries.html

A very good rule to follow here is the "80% rule". This simply means that you should never discharge a LiPo pack down past 80% of it's capacity to be safe. For example, if you have a 2000 mAh LiPo pack, you should never draw more than 1600 mAh out of the pack (80% x 2000). This is assuming a healthy pack as well that has the full 2000 mAh capacity (as packs age, their capacity drops).

This again is where computerized chargers pay for themselves many times over so you can see how much capacity the battery takes allowing you to adjust your flight times accordingly to stay within that 80% rule to get the most life out of your pack.

If you don't have a computerized charger to confirm the amount of capacity, another good indicator is to measure the open circuit voltage (no load voltage) of the pack or individual cells after a flight/drive with a digital volt meter or other similar digital device. An 80% discharged LiPo cell, will give an approximate open circuit voltage of 3.73 to 3.75 volts. A 3S LiPo pack therefore would show about 11.19 to 11.25 volts after a flight when it's 80% discharged, a 6S pack would be about 22.44 volts.

I imagine at 10.8 volts it will be pretty much shot. It might even be too hot to hold in your hand.

 

[Gizmo3000]

An 80% discharged LiPo cell, will give an approximate open circuit voltage of 3.73 to 3.75 volts. A 3S LiPo pack therefore would show about 11.19 to 11.25 volts after a flight when it's 80% discharged[/b],

Good to know.

What has me baffled is that I recently flew my batteries down to the flashing red lights.
so when I check it (on my new Hobby King checker), it's saying all the cells are around 3.75, that there's 11.23 volts.

but then there's a E::::F meter,.and it's saying the Lipo is 61% full?
(on about all my batteries in that same condition)
anyone got an idea what that's indicative of?

 

[colchester daz]

If i take the battery out at the 10.8v warning its not hot at all, not even remotley warm

 

[Boosted2000si]

I run mine to the first low battery lite. When I put it on the charger it says its at 11.0 volts. I then use the charger to discharge the rest it flashes to 3amps and ramps down as it runs the battery down to 10.8v. At that time I do a balance charge and seem to get 21XX mah back into the battery.

As far as using the battery down to 10.8 I'd say that's getting risky. I do it in a controlled environment with no chance to ruin it.

So far I have burnt 4 lipos running them to low in other rc toys and have lost over $200 for it. I don't chance it anymore granted the phantom batteries are only $20-$30 just hate blowing cash if I don't have to.

 

[colchester daz]

A friend of mine has the same set up as mine, and when he was flying his yesrerday, he ignored the warning from the controller telling him low battery and waited for the Phantom to indicate low battery, when he landed it was at 9.8v and was quite warm!

If i stopped at 11.2v my fly time would be so short!

 

[Gizmo3000]

a controller telling you how low the battery is? how's that done?

 

[colchester daz]

Im using a Devention Devo 10 tx, you can display on the controller the voltage of the battery, its quite cool to see how much the battery voltage dips from a hover to a full power lift, ive set it to alarm me at 10.8v, it will beep and vibrate in your hand.