REDARC BCDC DC-DC Chargers
Charge As You Drive, Properly
A DC-DC charger keeps your house battery fully charged from your alternator and solar while you're on the move — safely, and at the right charge profile for lithium. We supply and install REDARC's rugged BCDC range, set up for your vehicle, at our Christchurch workshop.
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What a DC-DC Charger Actually Does
A DC-DC charger — also called a B2B or battery-to-battery charger — sits between your vehicle's starter battery and your auxiliary "house" battery. As you drive, it takes power from the alternator and delivers it to the house battery at the exact voltage and multi-stage charge profile that battery needs.
It sounds simple, but it solves two real problems that a basic wired connection or old-style isolator can't — and on a modern vehicle with a lithium house battery, it's essential rather than optional.
The Two Problems It Solves
1. Modern "smart" alternators. Newer vehicles vary their alternator voltage to save fuel and cut emissions — they no longer hold a steady 14V+. Wired directly, your house battery may sit chronically half-charged. The DC-DC charger boosts and regulates that variable voltage back up to a proper, full charge.
2. Protecting your alternator from lithium. Lithium batteries draw hard — connected straight to an alternator they demand maximum output, which can overheat and damage the alternator, especially at idle. The DC-DC charger limits and controls that draw, protecting the alternator while still charging fast.
A typical BCDC setup: alternator and solar in, a properly charged house battery out.
Who It's For
Do You Need One?
If any of these sound like you, a DC-DC charger will make a real difference — and if you're running or moving to lithium, it's a must.
Motorhomes & Caravans
Keep the house battery charged on every drive between stops, so you arrive with power ready to go.
4x4 & Touring Setups
Dual-battery rigs running fridges, lights and gear off-grid — the classic BCDC use case.
Lithium Upgrades
Switching to LiFePO4? A DC-DC charger is essential to charge it correctly and protect your alternator.
Solar + Driving Combined
The BCDC takes solar input too, blending both sources so your battery charges however you're travelling.
Why REDARC
Built Tough, Built to Last
REDARC's BCDC range has powered off-grid touring for over a decade. It sits at the premium end of the market — and for good reason. Here's what you're paying for. (Wondering how it stacks up against other brands? See our honest REDARC vs Victron vs Renogy comparison.)
Australian-Built & Rugged
Designed and made in Australia with IP67/69K dust and moisture protection — built for the heat, dust and vibration of real touring, including under-bonnet mounting on the right models.
Start Battery Recovery
The only DC-DC charger that can also recover a flat start battery — revive it in as little as 15 minutes at the press of a button or from the app. Never stranded.
Green Power Priority
Prioritises free solar power over the alternator, cutting the load on your engine and saving fuel while you drive.
Alternator Protection
Customisable input current limiting protects your vehicle's alternator — ideal for modern, hybrid and EV setups where that matters most.
Solar Controller Built In
An efficient MPPT solar regulator is built in, so the one unit charges from both the alternator and your panels — simultaneously, and correctly.
Lithium-Ready
Correct charge profiles for lithium (LiFePO4) as well as AGM, gel and flooded — so your battery fills properly and lasts.
See It in Real Time
Your Whole System, In Your Pocket
The BCDC Alpha R range connects over Bluetooth to REDARC's RedVision app, so you can check your power at a glance — from the driver's seat or the campsite.
- Live charge status — see exactly what's coming in from the alternator and solar.
- Battery health — voltage, temperature and state of charge at a glance.
- Start battery recovery — trigger it right from your phone if you're caught out.
- Smart Battery Monitor — the Alpha R models include it, for a true picture of your system.
Which Model?
Getting the Size Right
1
How big is your house battery? A good rule of thumb is a charger rated around 10–20% of your battery's amp-hour capacity — so a 200Ah bank suits roughly a 25–50A charger. We'll confirm the exact match.
2
Where will it be mounted? Some BCDC models are rated for hot under-bonnet installation, others are designed to live in the living space. The right pick depends on your vehicle.
3
Do you want built-in monitoring? The Alpha R models add RedVision connectivity and a Smart Battery Monitor — worth it if you like to keep an eye on your power.
4
Not sure? Tell us your vehicle, your battery and how you travel, and we'll spec and install the right BCDC for the job. Our solar calculator is a handy starting point too.
REDARC recommends installation by a qualified auto electrician or technician. Model names, availability
and specifications are current REDARC information and may change — we'll confirm the right current
model for your build when you enquire.
Get Your BCDC Installed Right
A premium charger is only as good as its install. Tell us about your vehicle and how you travel, and we'll supply and fit the right REDARC BCDC — sized, wired and set up properly. Honest advice, no obligation.
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