3.11 Battery charging information
The charge controller starts a new charge cycle every morning, when the
sun starts shining.
Lead-acid batteries: default method to determine length and
end of absorption
The charging algorithm behaviour of MPPTs differs from AC connected
battery chargers. Please read this section of the manual carefully to
understand MPPT behaviour, and always follow the recommendations of
your battery manufacturer.
By default, the absorption time is determined on idle battery voltage at the
start of each day based on the following table:
Battery voltage Vb
(@start-up)
Vb < 11,9V
11,9V < Vb < 12,2V
12,2V < Vb < 12,6V
Vb > 12,6V
(12V values, adjust for 24V))
The absorption time counter starts once switched from bulk to absorption.
The MPPT Solar Chargers will also end absorption and switch to float when
the battery current drops below a low current threshold limit, the 'tail current'.
The default tail current value is 2A.
The default settings (voltages, maximum absorption time and tail current)
can be modified with the Victronconnect app via Bluetooth or via VE.Direct.
There are two exceptions to normal operation:
1. When used in an ESS system; the solar charger algorithm is disabled;
and instead it follows the curve as mandated by the inverter/charger.
2. For CAN-bus Lithium batteries, like BYD, the battery tells the system,
including the solar charger, what charge voltage to use. This Charge
Voltage Limit (CVL) is for some batteries even dynamic; changes over
time; based on for example maximum cell voltage in the pack and other
parameters.
When, in case of the above-mentioned exceptions, several solar chargers
are connected to a GX device, these chargers will automatically be
synchronised.
12
Multiplier
absorption time
x 1
x 2/3
x 1/3
x 1/6
Maximum
6h
4h
2h
1h