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DRAFT
Problems caused by excessive LiFePO4 charging voltage
So your LiFePO4 battery is acting up:
It's fairly common for excessive charging voltage to cause these symptoms. Unfortunately it's very common for preconfigured Lithium profiles to charge at these voltages.
TLDR
If this is the problem then reducing the charging voltage to something like 13.6v will cause the symptoms to improve.
about these summaries]
the full process
reduce charging voltage (aka “absorption voltage”, “boost voltage”)) to something like 13.6v and float voltage, if used, to something like 13.4v.
observe for a few days. Charging will be slower and may not finish by sundown
1), but we are most interested in whether or not the symptoms above clear up.
if they do clear up you can start to raise the charging voltage back up gradually (13.65v, 13.7v, 13.74v, etc) or you can leave it low. {note from secessus: there is little benefit to charging LiFePO4 >13.8v.] Float can remain at 13.4v.
if it starts acting up again drop charging voltage back down
why the problem occurs
lithium cell voltages are very “flat” for most of their usable capacity. When deeply discharged the voltage drops off dramatically, and when they are overcharged their voltage spikes dramatically. Because of the shape of this voltage curve we sometimes say there is a “lower knee”, broad flat middle, and “upper knee”.
when one cell hits overcharge first it can “run away” voltage-wise, and do so quite suddenly. This unevenness in cell voltage is called “imbalance” and is more likely to happen with higher charging voltages.
2)
the BMS sees the runaway and shuts down charging to avoid damaging the cell
which stops
all charging of the battery
3)
if the cell imbalance is bad enough the battery can't charge anywhere near full because the misbehaving cell is causing problems.
So we ease up on charging which encourages the cell to stay in line with the others, which allows for a full battery charge.
The bigger question is this: why do battery and charger manufacturers specify such high charging voltages in the first place?
further reading