Victron energy Blue Power IP22 Charger Manuel page 12

3.5 Estimating charge time
A lead-acid battery is about 80% charged at the beginning of the
absorption period.
The time T to 80% charged can be calculated as follows:
T = Ah / I
Where:
I is the charge current (= charger output minus load current).
Ah is the amount of Ah to be charged.
A full absorption period of up to 8 hours is needed to charge the
battery to 100%.
Example:
Charge time to 80% of a fully discharged 220Ah battery when
charged with a 30A Charger: T = 220 / 30 = 7,3 hours. Charge
time to 100%: 7,3 + 8 = 15,3 hours.
A Li-ion battery is more than 95% charged at the beginning of the
absorption period, and reaches 100% charge after approximately
30 minutes absorption charge.
3.6 High internal resistance
When a battery reaches the end of its cycle- or float life, or when
it dies prematurely due to sulfation or corrosion, capacity will
dramatically drop and internal resistance will increase. The
charger will not reject such a battery during the test phase (it
could as well be a nearly fully charged battery).
A very short bulk phase when charging a supposedly discharged
battery does however indicate that the battery has reached the
end of its useful life.
Remark: sulfation can sometimes be partially reversed by
repeated application of the RECONDITION MODE.
3.7 Can be used as a power supply
The charger will supply DC loads when no battery is connected.
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