"Charge Efficiency Factor CEF?"

MEXICOWANDERER wrote:
Like borrowing. You extract so much, but expected to put back a little extra to "settle the debt".

Predicated on measuring seasoned new batteries.

Expressed as a figure like 1.11, or 1.18, or 1.24

I used to use this all the time especially when dealing with gel batteries and absorbed glass mat. Coupling this figure with proven life cycle endurance used to reveal a lot about a battery.

But I don't see it used much, any more. I wonder why?

You need a amp hour counter that does not have a set stop point
You need to count what was used
Rest to zero
Count what it takes to get back to the specified volts~ amps reading that means full
Record the numbers and reset to zero for the start of the discharge cycle

You take those numbers out versus in and derive your cef factor

This isn't aimed at "Most Consumers". Let them Eat Cake :)

Too technical. Most consumers expect automatic charging.
CEF is better suited to an industrial setting.

Watt efficiency of charging is reduced as batteries acid regains density. From 95-100% CEF is about half that of 65% SOC. Remaining energy is diverted to thermal production and electrolysis of H2O. When the trends and tendencies of absorbed glass mat are considered versus those of a flooded lead antimony battery the curve remains higher for the AGM. This is a major influence on the higher CEF seen with the AGM.

cef 200% aka 'factor of 2'

7ah battery discharge via 5 watts of LEDs for 3 hrs/night
recharged daily via ample solar (60 watt) - default sealed setting - 14.4, 13.8 - 2 hr abs, 14.6 every 30 days for additional 2 hrs.
@ 400 daily cycles the recharge was just under twice the discharge accumulators, including all the hrs floated and slow charging till noon (shade).
last 30 days the recharge is just over twice the discharge.

is the CEF 50% or 200% or 2.0?

The Trimetric AH counter uses this factor when recharging. Good discussion of it in their owner's manual.

Note on P10 page 12 of 16 here

http://www.bogartengineering.com/wp-content/uploads/docs/TM-2025%20Users%20Instructions9-11-12.pdf

Because of the automatic mindset prevalent today.

My solar controller can have a charge efficiency setpoint automatic or fixed, but other charging sources seem to like to make it choose 99% on automatic.

I set it to a fixed 92% and when amps taper to 0.4 for a 90AH AGM, the AH counter is usually down to 0 from full, or relatively close.

Still really do not trust it. I always look at amps at absorption voltage, then raise an eyebrow at the AH from full figure my battery monitor is displaying.