Victron energy 6V/12V-1,1A Manuel page 5

[5] Whenever possible, disconnect and remove the battery from the
vehicle before charging. Read section 6, Safety Instructions for
more information.
[6] Connect the crocodile clamps to the battery in the following
sequence:
First, connect the positive charging lead (red) to the positive
terminal.
Second, connect the negative lead (black) to the negative
terminal.
It is extremely important to ensure that both crocodile clamps are
properly in contact with the respective terminals, otherwise it
might not be possible to complete the charging cycle.
[7] When the battery leads are in their correct position, connect
the power cable to the power supply. In case of reverse polarity
connection the fault indicator LED (!) will light up. Unplug the
charger and reconnect with the correct polarity.
[8] 6V battery
If the battery is between 2V+/-0.5V and 7V+/-0.25V, the charger
will begin charging. If the voltage is greater than 7V+/-0.25V, the
charger will not begin charging but will go into failure mode.
[9] 12V battery
If the battery is between 7V+/-0.25V and 14V+/-0.25V, the charger will
begin charging. If the voltage is greater than 14V+/-0.25V, the charger
will not begin charging but will go into failure mode.
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