Charger settings for 48v Lifepo4 - Maximum battery life

[WolfbaneAries]

Currently I am using the charging settings recommended by Victron for my 48v Lifepo4 battery bank (3 sets of 16s 280ah cells):

Absorption: 56.4v
Float: 54.4v

I have read and heard a number of times that for maximum battery life (number of charge cycles), the batteries should be charged no more than 80% and discharged no more than 20%. Copied/pasted below is an example of such a chart (12v example).

It seems to me that my current charger settings get the battery closer to the 99% mark. What are your thoughts on charging only to 80% to maximize the lifespan of lifepo4 cells, and what Absorption and Float settings would you recommend to achieve that? At one point I was using 54.4v absorption and 53.6v float which seemed to get it into that 80% range, but then again it leaves quite a bit of power on the table that could be used when there are long stretches of cloudy days.

Voltage	Capacity	Charge Cycles	Lifespan (Above 80% Original Capacity)
(V)	(Ah %)	(If charged and discharged to each of these voltages every day)	(Charged once a day)
14.4V	100%	3200 cycles	9 years
13.6V	100%	3200 cycles	9 years
13.4V	99%	3200 cycles	9 years
13.3V	90%	4500 cycles	12.5 years
13.2V	70%	8000 cycles	20 years
13.1V	40%	8000 cycles	20 years
13.0V	30%	8000 cycles	20 years
12.9V	20%	8000 cycles	20 years
12.8V	17%	6000 cycles	16.5 years
12.5V	14%	4500 cycles	12.5 years
12.0V	9%	4500 cycles	12.5 years
10.0V	0%	3200 cycles	9 years

 

[fmeili1]

As far as I remember, this 80% / 20% rules does not really belong to LiFePO4 (LFP). Instead it's more important for other Lithium chemistry batteries (e.g. LCO, LMO, NMC, NCA, LTO, etc.). Will has made a video about that a while ago...

 

[DIYrich]

The 80/20 rule is also true for lifep04, but in the solar context calendar age is more an issue than daily cycling. In essence the additional 30% (10% for reserve) is free capacity. 15 years of daily cycling is 5,500 cycles. Keep charge rate under 0.2c and discharge rate under 0.5c, and you should be able to exceed the cycles in the table. I believe those numbers are for 1c/1c.

 

[ArthurEld]

If you use the 80/20 rule, do you ever use a ballencer?