Redarc BCDC1220 20A under-bonnet DC-DC charger front view, black potted housing with Redarc branding

Redarc

BCDC1220 — 12V 20A Under Bonnet DC-DC Charger

Name: Redarc BCDC1220 — 12V 20A Under Bonnet DC-DC Charger
Brand: Redarc
SKU: BCDC1220
Price: 520.00 AUD
Availability: InStock

BCDC1220

12V 20A DC-DC charger that sits under the bonnet and charges a 12V lead-acid auxiliary bank from the alternator while driving. Supports AGM, gel, calcium and standard lead-acid; does NOT support LiFePO4 lithium (use BCDC1225D Classic25 or BCDC2420 for lithium banks).

$520.00

4 interest-free payments of $130.00 with Afterpay

or finance your build with Allied Finance

We accept Visa Mastercard Amex Apple Pay PayPal Zip Afterpay Finance

Universal fitment12V 20A DC-DC charger for 12V lead-acid auxiliary banks

Shipping & collection

Worldwide shipping available^*

In-store pickup

Professional installation available

*Shipping is calculated at checkout based on your location. Some products can't be delivered to every address.

20A UNDER-BONNET DC-DC

Compact charger sized to mount in the engine bay of most 4WDs and utes.

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

Selectable profiles for AGM, gel, calcium, standard lead-acid and LiFePO4 lithium banks.

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 sits under the bonnet and charges a lead-acid auxiliary battery from the vehicle's alternator while driving. Multi-stage profile for AGM, gel, calcium and standard lead-acid banks. Pairs the start battery with the auxiliary bank in a 4WD, ute, van, camper or boat.

Potted construction, no fan, rated for engine-bay heat, water and vibration. Case is 100 by 120 by 37mm and weighs 450 grams, so it fits in the tight spaces most engine bays leave for aftermarket gear. Wire terminals are bare-wire tails straight off the unit, so cable size follows the install.

Output is always 12V, regardless of input. The 9-32V input range covers 12V and 24V vehicles, but a 24V auxiliary bank needs the BCDC2420 instead. The plain BCDC1220 does NOT support LiFePO4 lithium banks; Redarc publishes lead-acid-only chemistry support on this SKU. For a lithium auxiliary bank, specify the BCDC1225D Classic25 (lithium-capable) or the 24V BCDC2420.

What sets it apart

Multi-stage charging — AGM, gel, calcium, standard lead-acid

Potted construction — rated for engine-bay heat and vibration

Fanless silent operation — no moving parts to fail

9-32V DC input — covers 12V and 24V vehicle input

12V output — always 12V, regardless of input voltage

Bare-wire tails — size cable to the install, crimp lugs to suit

Made in Australia — built at Redarc's Lonsdale SA facility

Mounting and install

Mounts under the bonnet or in-cabin with the supplied bracket hardware. The potted body is sealed and fanless, rated for engine-bay heat, water spray and vibration. Allow 50mm clearance around the body for air flow; orientation is not restricted.

Wire with 6 B&S from the start battery to the charger's input tails and 6 B&S from the output tails to the auxiliary bank. Install a 16-23A MIDI fuse within 300mm of the start battery and a 31A MIDI fuse within 300mm of the auxiliary bank, matching Redarc's input and output fuse specs. On a smart-alternator vehicle or multi-charger setup, hardwire a switched-12V ignition trigger from the ignition pin.

Pairs with

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

$799.00

Redarc BCDC1225D Classic25 — 12V 25A DC-DC Charger with MPPT Solar Input

$520.00

Multi-stage charging — AGM, gel, calcium, standard lead-acid
9-32V DC input — covers 12V and 24V vehicle input
12V output — always 12V, regardless of input
Potted construction — rated for engine-bay heat and vibration
Fanless silent operation — no moving parts to fail
Bare-wire tails — size cable to the install
Made in Australia — Redarc Lonsdale SA facility

Electrical

Input Voltage: 9-32V DC

Output Voltage: 12V DC

Max Charging Voltage: 15.3V

Output Current (12V in): 11A

Output Current (24V in): 20A

Standby Current: <5mA

No-Load Current: <100mA

Chemistry support

Supported: AGM / Gel / Calcium / Standard Lead-Acid

Not supported: LiFePO4 lithium

Fuses (not supplied)

Input Fuse: 16-23A MIDI

Output Fuse: 31A MIDI

Environment and build

Operating Temp: -20°C to +80°C

Engine-Bay Rated: Yes

Construction: Potted, fanless, bare-wire tails

Length: 100mm

Width: 120mm

Height: 37mm

Weight: 0.45 kg

Mount under the bonnet or in-cabin with the supplied bracket hardware. The potted body is sealed and fanless, rated for engine-bay heat, water spray and vibration. Allow 50mm clearance around the unit for air flow. Orientation is not restricted.

Wire with 6 B&S cable from the start battery to the charger's input tails and 6 B&S from the output tails to the auxiliary bank. Install a 16-23A MIDI fuse within 300mm of the start battery (Redarc's input spec) and a 31A MIDI fuse within 300mm of the auxiliary battery (Redarc's output spec). Keep the earth path through the vehicle chassis short.

On a smart-alternator vehicle or multi-charger setup, hardwire a switched-12V ignition trigger wire to the charger's ignition pin to prevent current draw when the engine is off. Standard alternators work fine on voltage sensing alone and don't need the ignition trigger. Chemistry profile selection: set the profile switch for AGM, gel, calcium or standard lead-acid before connecting the auxiliary bank. Do NOT connect a LiFePO4 lithium bank; this charger is lead-acid only.

12V 20A DC-DC charger for 12V lead-acid auxiliary banks

12V vehicles with alternator or smart-alternator (fit the BCDC1220-IGN variant on stop-start or variable-voltage alternators)

24V input vehicles (output always 12V)

Lead-acid chemistry: AGM, gel, calcium, standard lead-acid

CRITICAL: Not compatible with LiFePO4 lithium banks — use BCDC1225D Classic25 or BCDC2420 instead

CRITICAL: 24V auxiliary bank — use BCDC2420 (output on this unit is always 12V)

Q: What does DC-DC mean?
A: A DC-DC charger converts the alternator's 12V or 24V DC output into a regulated multi-stage charge for the auxiliary bank. Different from a smart isolator that just connects two batteries once the start battery is charged. The multi-stage profile means the auxiliary bank gets a proper bulk, absorb and float cycle, same as a mains charger would deliver.

Q: Which battery chemistries does it charge?
A: AGM, gel, standard lead-acid and calcium. Redarc publishes this charger as lead-acid-only and does NOT support LiFePO4 lithium on the plain BCDC1220. For a lithium bank, specify the BCDC1225D Classic25 (lithium-capable at 25A) or the BCDC2420 (if the auxiliary bank is 24V).

Q: Does it work with smart alternators?
A: The plain BCDC1220 uses voltage sensing and is suitable for older non-variable alternators. For stop-start or variable-voltage alternators (common on vehicles built from about 2015 onwards), fit the BCDC1220-IGN variant instead; it takes an ignition trigger wire rather than relying on voltage sensing.

Q: What's the real output on a 12V vehicle?
A: Redarc publishes 11A continuous output on a 12V vehicle input, 20A continuous output on a 24V vehicle input. The 20A rating refers to the 24V-input case; on a 12V vehicle the charger will deliver 11A continuous into the auxiliary bank. This is physics (a 1:1 DC-DC can't source 20A at 12V from a 12V input). The Classic25 (BCDC1225D) at 25A continuous is a better fit for 12V-input installs that need a higher charge rate.

Q: Where does it mount?
A: Under the bonnet or in-cabin. The potted sealed body is rated for engine-bay heat, water and vibration. Allow 50mm clearance around the body for air flow. Orientation is not restricted.

Q: What cable size should I run?
A: 6 B&S cable on the input side from the start battery and 6 B&S on the output side to the auxiliary bank for most installs under 2m. Over 2m, step up to 4 B&S to keep voltage drop in check. Our workshop runs 6 B&S for all standard dual-battery installs on this charger.

Q: What fuses do I need?
A: Redarc specifies 16-23A on the input side and 31A on the output side, both in MIDI fuse holders within 300mm of their respective batteries. The MIDI series fits those ratings cleanly (we typically run 20A MIDI input and 30A MIDI output).

Q: Does it have solar input?
A: No. The plain BCDC1220 is DC-DC input only, no MPPT. If you also want to charge from solar when parked, specify the BCDC1225D Classic25 (12V) or BCDC2420 (24V) instead; both carry an MPPT solar input alongside the DC-DC input.

Q: Can I charge a 24V auxiliary bank with this?
A: No. Output is always 12V, regardless of whether the input vehicle is 12V or 24V. For a 24V auxiliary bank, use the BCDC2420 (12V/24V input, 24V output at 20A).

Q: How big an auxiliary bank will it run?
A: Rule of thumb: match the DC-DC output amperage to about 10-20% of the battery bank's amp-hour capacity. At 11A continuous (12V input) this suits a 55-110Ah lead-acid auxiliary bank. For larger banks, step up to the BCDC1225D Classic25 (25A) or BCDC1250D Classic50 (50A).

Cart 0

Sorry, looks like we don't have enough of this product.