Optimal DOD (Depth Of Discharge) varies by battery formulation!

(These 3 discharge profiles are all Lithium Cobalt variations.)

Optimal discharge voltages vary between 3.5V - 3.65V - 3.75V!

Some cell types retain good energy density right to about 4.20V while another had poor energy density till below 4.10V

1st step is to determine the best high and low voltage for your battery pack.

I demonstrated a couple methods in earlier in thread.

Simplest?

1. Find a "track", circular path of moderate length. No stop signs or interruption is best.

(Around a block?, back and forth along an open road or trail?)

Charge battery pack to its maximum recommended voltage (4.2V per cell?).

Attach voltage meter to pack or to single bank. (100th V capability recommended.)

Object is - to determine the variance of voltage loss at various starting voltages, using identical amounts of power usage.

2. Run identical laps, same speed and throttle usage.

Release throttle, at the same point, several seconds before passing your start point. (should recover from voltage sag)

Call out voltage as you pass your start point, have a friend charting your voltage. (Graph paper is nice or chart into graph program to see results?)

Initial lap(s) should show a heavy drop.

Severity of drop will decrease and stabilize.

At some point the severity of drop will increase, this would be your maximum DOD.

(This method will give you a chart similar to the common discharge graph, without the drastic voltage sag.)

You should be able to determine your optimal charge voltage and discharge voltage.

You want to stay within the stable area of the graph, charge to below the sharp initial drop and do not discharge below the point where the drop again sharpens.

Charging to a voltage where little energy is retained is needlessly damaging.

Deeply discharging where minimal energy is available is needlessly damaging.

Staying within your batteries optimal range will greatly increase its lifespan and preserve its performance.

Note: LiFePO4 and similar formulations have the majority of there energy concentrated in a narrow voltage range!(Near the 3.2V region)