Saito ProCharger S Operating Instructions Manual page 19

Charging process
For the charging operation itself it does not matter whether the battery
is only partly or completely discharged. The battery can also remain
permanently connected to the charging device; however the
surrounding temperature should not exceed approx. 40°C! If the battery
is connected to the charging device with reversed polarity by mistake,
this will be signalised by means of a red "Polarity reversal" LED and the
charging current will be turned off at the same time.
Charging shut-down
The charging devices features a shut-down function which automatically
ends the charging process when reaching charging end voltage and
independently switches to trickle charging mode.
The yellow charging display will switch off in trickle charging mode resp.
if the charging current is reduced to less than 80 mA.
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