Sorry, little off topic.
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In the settings there are only:
Absorb,float and eq. How does the SCC know at what voltage to charge, 14.4 let's say for most lithium's? I read on victron forum that absorb = bulk, but that just doesn't make sense!
You are right, there are only three voltage settings for the MPPT SCC:
Absorb
Float
Equalize.
There are four charging modes:
Bulk
Absorb
Float
Equalize.
BULK charging is constant current charging.
In reality with a Solar Charge Controller, Bulk charging is the Max constant current charge available from the Solar Panels that is within the rated current of the SCC. SO if your SCC has a current output rating of 30A, that would be a 30A constant current charge (or max solar amps available less than or equal to 30A depending on solar panel sun conditions. Clouds, shadows can distract from max solar output, resulting in less than rated current output).
The SCC output voltage is monitored, and when the voltage is equal to the Absorb voltage, the charger goes into the Constant Voltage mode at the Absorb voltage set point.
ABSORB charging is constant voltage charging.
In reality with a Solar Charge Controller, the SCC maintains the set Absorb voltage. Absorb charging current is max current the battery/load will accept at the set Absorb voltage that is within the current rating of the SCC. Clouds, shadows can distract from max solar output, resulting in less than rated current output or loss of absorb voltage.
Absorb charging is terminated if the Solar Panels/SCC cannot maintain the absorb voltage set point, or in some cases if the battery attains a set SOC value, the charging current reduces to below a set current level or after a set absorb time.
FLOAT charging is constant voltage charging.
In reality the SCC targets a constant Float voltage, the battery drops from Absorb voltage set point to the Float voltage set point by supplying power to parasitic loads, small loads or battery cell voltage normalization.
Once the battery has reached the Float voltage, the Solar Panels/SCC maintain the float voltage until the load on the battery exceeds the power available from the Solar Panels/SCC causing the battery voltage to drop below a set point voltage variance below the Float voltage. Clouds, shadows can distract from max solar output, resulting in less than demanded power output and loss of Float charging.
At that point the SCC initiates a new Bulk charge. Once the Battery voltage has attained the Absorb voltage set point, the SCC goes back to the Float voltage set point.
The Victron SCC I have only allows the Absorb Voltage for any Solar cycle (solar day) to be in the absorb mode for a total time equal to the absorb time setpoint for any solar cycle (I do not use SOC or charging current set points to terminate the battery absorb charge).
Equalize charging is constant voltage charging.
Battery chemistry can demand equalize charging to extend the life of some batteries.
An Equalize charge for Lead Acid batteries is an occasional overcharging of the battery beyond 100% SOC to desulfate the lead plates and stur the electrolyte up a little. This produces Hydrogen that is vented from the battery. The electrolyte level drops, and the batteries have to be topped off with more water occasionally. Lead acid storage batteries have an equalize voltage and routine specified by their manufacturer.