Is the battery efficiency supplied by the manufacturer the round trip from 100% to 50% to 100% @a c/20 charge/discharge rate?
What does the wizbang use that value for?
The amp-hour efficiency is used so that it knows how many amp-hours to put back into the battery to replenish what it took out.
It should be in the 90% range for lead-acid and the high 90% range for lithium
In addition to what boB mentioned:
This Efficiency is the Charge Efficiency of the battery. This factor will vary, at least a bit, depending upon the DOD that the battery experienced in the previous discharge.
FLA Lead-Antimony batteries are fairly inefficient. This is in large part, due to the conversion of the water in the electrolyte into Oxygen and Hydrogen, after the Gassing Voltage has been reached, primarily, during Absorb.
The FLAs Lead-Antimony batteries that I have experience all run a bit below the manufacturer-stated value of 80% Charge Efficiency, nominal, at about 77%-ish.
Deeper discharges yield a bit of an increase in this efficiency. My batteries are fairly old. As this type of battery ages, the negative plate is said to become "poisoned", by Antimony migration from the positive plate. This increases the Gassing in the battery, yielding increased water consumption, and resultant efficiency reduction.
This is all, IMO. Batteries seem to be much like people. Behavior varies, depending upon the treatment they experience, the environment etc. But FLAs can tolerate a fairly wide range of inattention and a bit of abuse, too ... and so on.
I am NO battery expert, but try treat batteries, like they are friends, upon which, we often rely.
FWIW, Vic