5. Charging algorithms
5.1. Battery selection
The charge algorithm of the charger must fit the battery type connected to the charger. The following table shows the three predefined battery types available. A custom battery type can be programmed by the user.
Charging voltages at room temperature:
MODE | ABS V | FLOAT V | STORAGE V | RECONDITION Max V@% of Inom |
|---|---|---|---|---|
NORMAL | 14.4 | 13.8 | 13.2 | 16.2@8%, 1h max |
HIGH | 14.7 | 13.8 | 13.2 | 16.5@8%, 1h max |
LI-ION | 14.2 | 13.5 | 13.5 | N/A |
For 24V battery chargers: multiply all values by 2.
NORMAL (14.4V): recommended for wet-cell flat-plate lead-antimony batteries (starter batteries), flat-plate gel and AGM batteries.
HIGH (14.7V): recommended for wet-cell lead-calcium batteries, Optima spiral cell batteries and Odyssey batteries.
LI-ION (14.2V): recommended for Lithium Iron Phosphate (LiFePo4) batteries.
CUSTOM (Adj.): recommended for any other type of battery other the the above mentioned if the adjustable voltages are set according to the battery manufacturer recommendations.
MODE button
Once the battery charger has been connected to the AC power supply, press the MODE button to select a different charging algorithm if required (the battery charger remembers the mode after disconnecting the power supply and/or battery).
After selecting reconditioning, the RECONDITION LED will light up and start to blink when reconditioning is active.
The battery charger switches to LOW (low power) when the MODE button is held down for 3 seconds. The LOW LED will then remain lit. LOW mode will remain active until the MODE button is held down for another 3 seconds.
When LOW is active, the output current is limited to max. 50% of the rated output power.
Intelligent 7-stage charging algorithm for lead acid batteries: (with optional reconditioning)
BULK
Charges the battery using the maximum current until the absorption voltage is reached. At the end of the bulk phase, the battery will be about 80% charged and ready for use.
ABS - Absorption
Charges the battery using a constant voltage and a decreasing current until it is fully charged. See the above table for the absorption voltage at room temperature.
Variable absorption time:
The absorption time is short (at least 30 minutes) if an almost fully charged battery is connected and increases to 8 hours for a totally discharged battery.
RECONDITION
RECONDITION is an option for the NORMAL and HIGH charging programs and can be selected by pressing the MODE button again after selecting the desired charging algorithm.
During RECONDITION, the battery is charged to a higher voltage using a low current (8% of the rated current). RECONDITION takes place at the end of the absorption phase and ends after one hour or sooner once the higher voltage has been reached.
The RECONDITION LED will be lit while charging and will blink during RECONDITION.
Example:
For a 12/30 battery charger: the reconditioning current is 30 x 0.08 = 2.4A
FLOAT
Float charging. Keeps the battery at a constant voltage and fully charged.
STORAGE
Storage mode. Keeps the battery at a lower constant voltage to limit gas formation and corrosion of the positive plates.
READY (battery fully charged)
The battery is fully charged when the FLOAT or STORAGE LED is lit.
REFRESH
Slow self-discharging is prevented by automatically ‘refreshing’ the battery with a brief absorption charge.
5.2. Lithium-ion (LiFePO) batteries
When charging a lithium-ion battery, the charger uses a specific charging algorithm for lithium-ion batteries to maximise their performance. Select LI-ION using the MODE button. When using the Low battery temperature cut-off, charging will stop when batteries fall below 5°C (default) when coupled with a suitable VE.Smart networking temperature sensor, e.g. Smart Battery Sense or SmartShunt.
You can see when this feature is active by pressing the 'Why is my charger off?' button in VictronConnect and it will state that the charger is off due to a low battery temperature.
The voltage set points are set to lowest value possible (rather than switching the unit off completely), as it cannot be guaranteed that a battery voltage is always present, which is required for the charger to switch off.
Some lithium batteries with built-in BMS will cut themselves off in case of over/under voltage or temperature, this includes Victron Smart Lithium batteries. Since the BMS will disable the charge when the batteries are below 5°C, and also in case of cell over voltage.
It is not necessary to use the VE.Smart sense feature, or buy a Smart Battery Sense to make sure a Smart Charger stops charging a Victron Smart Lithium Battery below 5°C, when correctly installed with a BMS.
5.3. Fully user-programmable charging algorithm
If the three pre-programmed charging algorithms are not suitable for your purposes, you can also program your own charging algorithm using Bluetooth or the VE.Direct interface.
If a self-programmed charging algorithm is selected, the NORMAL, HIGH and LIION LEDs will not be lit. The status LEDs indicate the location of the charging program in the charger.
If the MODE button is pressed during a self-programmed charging algorithm, the charger will return to the pre-programmed NORMAL charging algorithm.
5.4. If a load is connected to the battery
A load can be applied to the battery during charging. Note: The battery will not be charged if the load current exceeds the output current of the battery charger. Reconditioning will not be possible if a load is connected to the battery.
5.5. Starting a new charging cycle
A new charging cycle starts if:
The charger is in the float or storage phase and the current rises to its maximum value for more than 4 seconds due to a load.
The MODE button is pressed while charging.
The mains power is disconnected and reconnected.
5.6. Calculation of the charging time
A lead battery is about 80% charged at the start of the absorption phase.
The time T until 80% charged can be calculated as follows:
T = Ah / I
In which:
I is the charging current (= current from the charger minus any current due to a load).
Ah the number of ampere hours that should be charged.
A full absorption period up to 8 hours will be required to charge a battery 100%.
Example:
Charging time to 80% for a fully discharged 220Ah battery when charging it with a 30Abattery charger: T = 220 / 30 = 7.3 hours.
Charging time to 100%: 7.3 + 8 = 15.3 hours
A Li-ion battery is more than 95% charged at the start of the absorption phase and will be fully charged after about 30 minutes of absorption charging.
5.7. Use as a power supply
The charger can be used as a power supply (a load is present but no battery is connected). The supply voltage can be set using Bluetooth or the VE.Direct interface.
When used as a power supply, only the BULK, ABSORPTION, FLOAT and STORAGE LEDs will light up and remain lit.
When the charger is set up as a power supply, it will not respond to the remote on-off.
If the MODE button is pressed while using the charger as a power supply, it will return to the pre-programmed NORMAL charging algorithm.