REDARC LFP2420-LV 24V 20A LiFePO4 DC-DC charger for variable-voltage alternators24V 20A LiFePO4 charger for 12V smart-alternator vehicles, with MPPT solar input

Overview

The LFP2420-LV charges a 24V LiFePO4 auxiliary battery at 20A and 600W from a 12V vehicle whose ECU-controlled alternator lowers its output voltage. Thresholds of 12.0V on and 11.9V off, with the blue wire on ignition, keep it charging where the standard LFP2420 would switch off. It follows a lithium-only algorithm of 28.8V absorption and 27.2V float. When parked, unregulated 12V panels with a Voc of 17.5–32V can feed it through the built-in MPPT regulator. REDARC states it is not suitable for 24V vehicles.

• 24V output at 10A (BCDC2410) or 20A
• Charges from a 12V or 24V vehicle, or 12V solar
• Built-in MPPT regulator for unregulated 12V panels
• BCDC for lead-acid, LFP for LiFePO4 batteries
• LV versions for 12V variable-voltage alternators
• Sealed, fan-free, 150×120×37mm

How it works

These chargers boost or reduce the input to deliver a 24V three-stage charge, so a 12V vehicle can charge a 24V auxiliary bank, or a 24V truck one at the end of a long cable, and they isolate the start battery. Each has a single power input on the red wire: the blue source-select wire tells the charger whether that input is a vehicle battery or an unregulated 12V solar panel, which is then handled by the internal MPPT regulator.

Boost runs at constant current up to the absorption voltage; absorption ends after a set time or when current falls below 4A for 30 seconds, then float maintains the battery. Automatic timeouts restart the cycle if a battery has not completed charging.

Models and battery types

BCDC2410 (10A, 300W) and BCDC2420 (20A, 600W) charge lead-acid, calcium, gel and AGM batteries with profiles A (29.2V), B (30.0V) and C, set with the orange wire, and float at 26.6V. LFP2420 charges LiFePO4 batteries at 28.8V absorption and 27.2V float, with no profile wire. The LV versions, BCDC2420-LV and LFP2420-LV, have lower turn-on thresholds (on at 12.0V, off at 11.9V) for 12V variable-voltage alternators and are not suitable for 24V vehicles.

Installation and compatibility

Mount the charger on a flat surface close to the auxiliary battery, away from heat, with four M6 fasteners; the output cable must not exceed 1m. Output derates above 55°C. For 20A models REDARC specifies at least 13.56mm² cable for 1–5m and 20.28mm² for 5–9m, and MIDI bolt-down fuses: 60A input from a 12V vehicle, 40A from a 24V vehicle, 30A on the output. The BCDC2410 uses 30A/20A input and 15A output fuses.

For alternator charging, connect the blue wire to ignition (12V only on BCDC2420) or permanently to the input positive on non-LV models; never connect it to ignition in a 24V system on the BCDC2420. For solar, leave the blue wire open or earthed, and use unregulated 12V panels with an open-circuit voltage of 17.5–28V (17.5–32V for LFP2420).

Status and protection

Front LEDs show charge mode or profile and charge status; the status LED blinks with a duty cycle that rises with current and stays on at full output. A green wire can drive an external dashboard LED without a resistor. All LEDs flash numbered codes for internal faults, over-temperature, high output voltage or reversed solar polarity, input under- or over-voltage and reverse polarity.

Questions and answers