Redarc BCDC1220-IGN 12V 20A under-bonnet DC-DC battery charger — front view of grey potted body with input and output terminals

Redarc BCDC1220-IGN rear mounting face with fixing holes for under-bonnet, cabin or canopy install

Redarc

BCDC1220-IGN — 12V 20A DC-DC Charger for Smart Alternators

Name: Redarc BCDC1220-IGN — 12V 20A DC-DC Charger for Smart Alternators
Brand: Redarc
SKU: BCDC1220-IGN
Price: 560.00 AUD
Availability: InStock

BCDC1220-IGN

12V 20A under-bonnet DC-DC charger with ignition-switched input for stop-start and variable-voltage smart alternators. Lead-acid chemistry only (AGM, gel, calcium, VRLA, standard lead-acid).

$560.00

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For 12V vehicles with ECU-controlled variable-voltage or stop-start smart alternators, charging a 12V auxiliary bank.

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20A FOR SMART ALTERNATORS

Ignition-switched input handles stop-start and variable-voltage alternators found on modern 4WDs.

3-STAGE CHARGING, ANY CHEMISTRY

Selectable charge profiles for AGM, gel, calcium, standard lead-acid and lithium banks.

SEALED FOR ENGINE-BAY HEAT

Rated to run in the engine bay of an Australian 4WD — dust, water and vibration tolerant.

LITHIUM AND AGM READY

Handles any modern deep-cycle chemistry — pick the profile and connect.

2 YEAR REDARC WARRANTY

Backed by 2 years direct from Redarc. Repair or replacement in accordance with Redarc's warranty policy.

A 12V 20A DC-DC charger that pulls from the start battery or alternator and runs a multi-stage charge into a 12V auxiliary bank. The ignition-switched input tells it when the vehicle's running, so it keeps charging reliably on late-model utes, 4WDs, vans and commercial vehicles whose smart alternators drop voltage while cruising. Fanless and fully potted, so it mounts under the bonnet, in a canopy or in a trailer tub.

The body is 100 by 120 by 37mm and weighs 450g. Three charging profiles (14.6V, 15.0V and 15.4V) cover AGM, gel, calcium, VRLA and standard lead-acid banks. A built-in start-battery isolator cuts the auxiliary off before cranking voltage drops too low. Operating range is -20°C to +80°C, with derating above 55°C in a hot engine bay.

This is a lead-acid charger, not a lithium one. Pair it with an AGM, gel, calcium or standard lead-acid auxiliary bank. For a LiFePO4 bank, use Redarc's dedicated lithium under-bonnet charger instead. For a 24V output, use the BCDC2420.

What sets it apart

Ignition-switched input — charges through stop-start and smart alternators

Potted and fanless — engine-bay rated, silent, no fan to fail

Three charge profiles — 14.6V, 15.0V and 15.4V to match the bank

Built-in isolator — protects the start battery during cranking

Lead-acid specialist — AGM, gel, calcium, VRLA and standard lead-acid

Full 20A continuous — delivers 300W into a 12V auxiliary bank

Designed and built in Australia — made by Redarc in Lonsdale, South Australia

Mounting and install

Mounts under the bonnet, in the cabin, in a canopy or on a trailer. The potted construction handles water, dust and vibration; keep ambient temperature under 55°C where possible to deliver the full 20A output. Allow 50mm clearance around the body for airflow.

Wire the input and output in 6 B&S cable with a 40A MIDI fuse within 300mm of each battery. Connect the blue ignition wire to a switched-12V source that goes live with the key on and dead with the key off, so the charger follows the ignition cycle on smart-alternator vehicles.

Pairs with

Redarc BCDC2420 — 24V 20A Under Bonnet DC-DC Charger with MPPT Solar Input

$799.00

Ignition-switched input — charges through stop-start and smart alternators
Potted and fanless — engine-bay rated, silent, no fan to fail
Three charge profiles — 14.6V, 15.0V and 15.4V to match the bank
Built-in isolator — protects the start battery during cranking
Lead-acid specialist — AGM, gel, calcium, VRLA and standard lead-acid
Full 20A continuous — delivers 300W into a 12V auxiliary bank
Designed and built in Australia — made by Redarc in Lonsdale, South Australia

Electrical

Input Voltage: 9-32V DC

Output Voltage: 12V DC

Output Current: 20A continuous

Output Power: 300W

Input Fuse: 40A MIDI

Output Fuse: 40A MIDI

Standby Current: <5mA

No-Load Current: <100mA

Charging

Charge Profiles: 3-stage multi-profile

Max Charge Voltage: 14.6V / 15.0V / 15.4V

Float Voltage: 13.3V

Chemistry: AGM, gel, calcium, VRLA, lead-acid

Environment and build

Operating Temp: -20°C to +80°C

Engine-bay Rated: Yes (derate above 55°C)

Construction: Potted, fanless

Length: 100mm

Width: 120mm

Height: 37mm

Weight: 0.45 kg

Mounts under the bonnet, in the cabin, in a canopy or on a trailer. The potted, fanless construction handles water, dust and vibration; keep ambient under 55°C to run the full 20A output. Allow 50mm clearance around the body for airflow and leave the connector face accessible for wiring.

Wire input and output in 6 B&S cable, kept as short as practical. Fit a 40A MIDI fuse within 300mm of the start battery (input) and a second 40A MIDI fuse within 300mm of the auxiliary battery (output).

The blue ignition wire goes to a switched-12V source that goes live with the key on and dead with the key off. Pick up from a factory ignition circuit the ECU already recognises so the charger follows the ignition cycle on smart-alternator vehicles. Set the chemistry profile with the external switch to match the auxiliary bank (A for standard lead-acid, B for AGM/calcium, C for deep AGM/gel/calcium).

For 12V vehicles with ECU-controlled variable-voltage or stop-start smart alternators, charging a 12V auxiliary bank.

Suits late-model utes, 4WDs, vans and commercial vehicles with smart alternators

Engine-bay rated — mounts under the bonnet or in the cabin, canopy or trailer

Ignition-switched input already built in — standard for smart-alternator installs

CRITICAL — not for LiFePO4 lithium banks; use Redarc's lithium under-bonnet charger instead

Not for 24V output banks — use the BCDC2420 for 24V

Q: What does DC-DC charger actually mean?
A: A charger that takes DC voltage from the vehicle (alternator or start battery, 9-32V) and converts it into a controlled DC charge for a second battery. It isn't a mains charger and doesn't need an AC source. Lets you run a dedicated auxiliary bank for fridges, lights, inverters and camping power without flattening the start battery.

Q: What does ignition-switched input actually mean?
A: Modern smart alternators drop voltage below 13V while cruising to save fuel. A standard DC-DC charger triggers off that voltage and switches off; the ignition-switched input gives it a separate 12V signal from the ignition that stays on while the engine runs, so charging continues reliably.

Q: Which vehicles need the IGN version?
A: Vehicles with stop-start, variable-voltage or ECU-controlled smart alternators. That covers most post-2015 utes, 4WDs, vans and commercial vehicles. The standard BCDC1220 (non-IGN) suits older vehicles with a fixed-voltage alternator. If the vehicle flashes a battery or charging warning when accessories switch on, the IGN version is the safer pick.

Q: Can this charge a LiFePO4 lithium bank?
A: No. The BCDC1220-IGN is a lead-acid charger. Its output profiles are built for AGM, gel, calcium, VRLA and standard lead-acid chemistry. Charging a LiFePO4 bank with it risks damaging the lithium BMS or shortening the bank's cycle life. For a LiFePO4 bank, use Redarc's dedicated lithium under-bonnet charger.

Q: Can I mount this in the engine bay?
A: Yes. The BCDC1220-IGN is engine-bay rated — the electronics are fully potted and the case is sealed against water, dust and vibration. Output derates above 55°C ambient, so pick a spot away from direct exhaust heat or the hottest part of the manifold to deliver the full 20A on hot days.

Q: What cable size and fuse rating should I use?
A: Redarc specifies 6 B&S cable for both the input and output runs on a typical install, with a 40A MIDI fuse within 300mm of each battery. In our workshop's experience that's the right call for most 12V installs — keep the runs short and don't go smaller than 6 B&S.

Q: Does it have a solar input?
A: No. The BCDC1220-IGN is a DC-DC-only charger with no built-in solar regulator. For solar top-up alongside DC-DC charging, step up to a BCDC with an MPPT input (such as the Classic25) or add a separate MPPT solar regulator in parallel on the auxiliary bank.

Q: What's the real output at 12V vehicle input?
A: 20A continuous — the full rated output into a 12V auxiliary bank. Delivers 300W into the bank regardless of whether the vehicle is 12V or 24V input, provided the input is in the 9-32V range.

Q: How do I size the auxiliary bank for this charger?
A: Rule of thumb — the charger comfortably handles AGM banks from about 50Ah up to around 200Ah. Below 50Ah risks over-current on a small bank; above 200Ah the charge time stretches out. A 100-120Ah AGM is the sweet spot for most 4WD, caravan and ute setups.

Q: How long is the warranty?
A: 2 years direct from Redarc. Covers manufacturing defects under normal use. If anything goes wrong in that window, bring it to us and we'll handle the claim.

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