Lowest voltage per cell to protect batteries?

[Vermiform]

What is the lowest voltage per cell I should fly at to maximize the life of my batteries. I just got some quality batteries in and I want to protect them.

I don't want the science behind it as I have read many threads on it today on other forums. What I'm looking for is just the number that ya'll fly to. I'm asking here because I trust the opinions on this forum more than anywhere else.

What say you?

 

[Buzz_Roavr]

On the iOSD hovering before landing 3.7v per cell.

Recovers pretty quickly on landing.

 

[fltundra]

Never lower then 3.6v per cell under load or 80% mah used which ever comes first. Correct way to know exactly is to use telemetry with current sensor w/radio or OSD. I have never hit 3.6v before the 80% mark.

View attachment 25490

 

[Bartman]

Landing with 3.7 volts per cell after shutting down generally leaves you flying to about 3.3 under load. By "under load" I mean if you're maneuvering or doing anything requiring greater than hovering power.

3.6 and 3.7 volts per cell are certainly useable limits but they'll shorten your flights where 3.3 gives better duration while also protecting cells.

YMMV

 

[Motopreserve]

I typically land with about 3.6 as well. It pops up after that. Not to get all scientific, but the 80% rule for voltage would be closer to @Bartman suggestion - which would be 3.36 per cell.

 

[fltundra]

I fly 23.5 min to 5800 mah with my tattu 4S7000mah 600g , 24.5 min with rmrc 15 month old 4S8000mah at around 6600mah used, 730g. Multistar 10c 4S10000mah 27 min to 8000mah used, 801g. None of them below 3.65v. At about 3-4ms forward flight, i can get about a 1 amp increase in efficiency over hover. I know the numbers are right on with using a Icharger 206b and cellpro 4c multi. and all my packs are holding perfect IR readings

 

[fltundra]

I typically land with about 3.6 as well. It pops up after that. Not to get all scientific, but the 80% rule for voltage would be closer to @Bartman suggestion - which would be 3.36 per cell.

Maybe your not using a high enough c rated lipo.

 

[fltundra]

This Lipo calculator gives cell and total voltage drop at different c ratings.
http://www.soko-heli-tools.com/en/lipo-battery-calculator/lipo-battery-calculator.html

 

[Motopreserve]

Maybe your not using a high enough c rated lipo.

Not sure I understand what you mean? I land just about exactly when you do. How does this equate to low C rating?

The IR on my packs are healthy too.

 

[fltundra]

Not sure I understand what you mean? I land just about exactly when you do. How does this equate to low C rating?

The IR on my packs are healthy too.

Was referring to 3.3 volts per cell, you'd probably pulling more then the pack can handle if we are talking at the 80% mark. It's always good too, to have an IR thermometer close by to check pack temps after landing. Wouldn't want to see anything above 120 deg, but that's just my opinion.

 

[Motopreserve]

That's why I don't risk it and fly that low. But the 80% rule would be 3.36v per cell. So anything above definitely should be safe.

I never loose steam or have any issues landing at 3.6-3.7v. So I stick with that and feel good about the health of the packs.

I like to take a break anyway, so I never fly until they're as low as 80%.

 

[Vermiform]

Good stuff guys, thanks for all the responses. That's why I ask here!

 

[Vermiform]

One last time.....

So if I have my APM set correctly measuring current and voltage accurately.....if I set an alarm for 25% left and begin my landing when it goes alerts, I should be good to go?