• Absorption time determined by tail current:
In some applications it may be preferable to terminate absorption time based on tail current only. This can be achieved by
increasing the default absorption time multiplier (warning: the tail current of lead-acid batteries does not decrease to zero when
the batteries are fully charged, and this “remaining” tail current can increase substantially when the batteries age).
Default settings for LiFePO4 batteries
The default absorption voltage is to 14.2V (28.4V, 56.8V) and the absorption time is fixed and set to 2 hours. The float voltage is
set at 13.2V (26.4V, 52.8V). Equalization is disabled. The tail current is set to 0A, this so that the full absorption time is available
for cell balancing. The temperature compensation is disabled and the low temperature cut off is set to 5. These settings are the
recommended settings for LiFePO4 batteries, but they can be adjusted if the battery manufacturer specifications advise
otherwise.
Reset of the charge algorithm:
The default setting for restarting the charge cycle is Vbat < (Vfloat – 0.4 V) for lead-acid, and Vbat (Vfloat – 0.1 V) for LiFePO4
batteries, during 1 minute. These values are for 12 V batteries, multiply by two for 24V and by four for 48V.
6.3. Automatic equalization
Do not equalize charge Gel, AGM, VRLA or lithium batteries.
Equalization can cause damage to the battery if the battery is not suitable for an equalization charge. Always
check with the battery manufacturer prior to enabling equalization.
Automatic equalization is by default disabled. When enabled, it can be configured with a number between 1 (every day) and 250
(once every 250 days).
When automatic equalization is active, the absorption charge will be followed by a voltage limited constant current period. The
current is by default limited to 8% of the bulk current and can be adjusted between 0% and 100%. The bulk current is set by
default to the maximum charge current the solar charger is capable of, unless a lower charge current has been chosen.
The maximum equalization duration is set by default to 1 hour and can be configured between 0 minutes and 24 hours. The
automatic equalization will end when the voltage limit has been reached or when the set maximum equalization duration has been
reached, whichever comes first.
When automatic equalization has not finished within a day, it will not resume the next day. The next equalization session will take
place as determined by the day interval.
6.4. Lithium batteries
Lithium Iron Phosphate (LiFePo4) batteries do not need to be fully charged to prevent premature failure. The default lithium (and
recommended) settings are:
Setting
12V system
24V system
48V system
Absorption voltage
14.2V
28.4V
56.8V
Absorption time
2h
2h
2h
Float voltage
13.2V
26.4V
52.8V
These settings are adjustable.
6.5. Shutdown and restart procedure
The solar charger is always active when the PV and/or the battery terminals are powered. The solar charger does not have an
on/off switch.
To shut down the solar charger, perform these steps in the prescribed order:
1. Disconnect the PV supply to the solar charger by switching the PV supply off or by removing the fuse(s).
2. Disconnect the battery supply to the solar charger by switching the battery supply off or by removing the fuse(s).
To restart the solar charger after it was shutdown, perform these steps in the prescribed order:
1. Connect the battery supply to the solar charger by switching the battery supply on or by inserting the fuse(s).
2. Reconnect the PV supply to the solar charger by switching the PV supply on or by inserting the fuse(s).
MPPT solar charger manual
Page 34
Operation
