Battery Charging Information - Victron energy BlueSolar MPPT 75/10 Mode D'emploi

3.8 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 behavior of MPPTs differs from AC connected battery chargers.
Please read this section of the manual carefully to understand MPPT behavior, 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))
Default absorption voltage: 14,4V
Default float voltage: 13,8V
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 1A.
For models with a load output the current on the battery terminals is used; and for the
larger models; the current on the output terminals is used.
The default settings (voltages, absorption time multiplier and tail current) can be modified
with the Victronconnect app via Bluetooth (VE.Direct Bluetooth Smart dongle needed) 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.
Variations to expected behaviour
1. Pausing of the absorption time counter
The absorption time counter starts when the configured absorption voltage is reached
and pauses when the output voltage is below the configured absorption voltage.
An example of when this voltage drop could occur is when PV power (due to clouds,
trees, bridges) is insufficient to charge the battery and to power the loads.
When the absorption timer is paused, the absorption LED will flash very slowly.
Multiplier Maximum absorption time
x 1
x 2/3
x 1/3
x 1/6
6h
4h
2h
1h
7