jmir

My Feedback: (1)

The E-flite ESC I just purchased is programmable.
The default setting includes a 70% voltage cutoff.
It can also be programmed for a 3-cell cutoff or a 6-cell cut off among other settings.

My battery pack is a 3S2P pack. That means it has a total of 6 cells.
Basically, it is two 3-cell packs joined in parallel. Voltage is 11.1v and amperage is doubled to 4400 mah.

Which is the correct setting for my 3S2P pack?

wswanepoel

Your ESC will see this as a 3 cell pack. Set it for 3 cell or for 70% is your choice. If programmed to 70% you can use it on different cell configurations without reprogramming.

jmir

My Feedback: (1)

Thanks for the info.

Do you now what 70% of what? Is it 70% of 11.1v? That would be 7.77v which is too low for a cut-off.
I think I will stick with the 3 cell set up just to make sure.

Thanks again.

Greg Covey

When a pack includes paralleled cells like your 3s2p (6-cell) pack, it is essentially a 3-cell pack for all practical purposes.

The 70% refers to 70% of battery starting voltage. You can see from the graph that on any LiPo pack, about 75% capacity will measure about 3.7v/cell or 11.1v (unloaded) on your 3-cell pack. A fully charged pack is 4.2v times 3 cells = 12.6v. (unloaded)

Working backwards...70% = Xv/12.6 so Xv = 12.6 * .7 = 8.82v
Divide 8.82v by 3 cells = 2.94v per cell (under load)

This is a safe cutoff voltage as your pack will never go under 3v per cell when the motor is running. After you land, you will find that the pack voltage is much higher than 3v per cell.

I'm not sure which setting gives you the longer run time; 3-cell or 70%. It is likely a setting used for heavy 3D flying so the motor is less prone to turn off until the battery is really depleted.

theradioflyer

Another note, if you use the 70% setting and fly with a partially charged batt it could be ruined because it is 70% of starting voltage.

God Bless,

Jay

jmir

My Feedback: (1)

Greg,

Thanks for the information. One thing about this hobby..... I am always learning something new!
I will try it both ways and see if there is any appreciable difference in flight times.

jmir

My Feedback: (1)

I guess this is something to keep in mind although I never fly with partially charged battery.

Thanks for comments.

wswanepoel

Yes as long as you don't get your charged and discharged batteries mixed up.