The best DC-DC chargers for a dual battery setup in Australia

A DC-DC charger is the box that charges a second battery properly from the vehicle’s alternator while you drive. Most also take a solar panel when you stop. If you are adding a lithium battery to a 4WD, ute or tow vehicle, this is the part that decides whether it ever reaches full. Prices are from Redarc, iTechworld, BCF and Anaconda on 18 October 2026; for models sold on Amazon Australia, check the current price on Amazon. We compared maker specifications and retailer listings; we have not bench-tested these chargers.

Get an auto electrician

This is the one product on the site we would not fit ourselves. A DC-DC charger connects to the starting battery with heavy cable, needs fuses at both ends (Redarc recommends 60A for the BCDC1240D and does not supply them), and often an ignition wire. Wrong cable size or a missing fuse at 40A is a fire risk. Buy the charger, then have an auto electrician install it with the battery, cable and fusing they specify. The prices below are for the unit only.

What to compare

Output current. 25A suits smaller batteries; 40A is the common choice for a 100Ah lithium battery. Redarc’s own guide puts its 40A chargers on lithium banks over 100Ah and lead acid over 200Ah. The battery’s maximum charge current is the upper limit: iTechworld and Hardkorr both allow 100A on their lithium batteries.

Solar input. All but the Victron have an MPPT solar regulator built in, so a portable solar panel plugs straight in. Check the voltage window: Redarc’s Classic and Core accept 9 to 32V, the Alpha 50 up to 48V, the Dune only 12 to 28V. Redarc’s “Green Power Priority” and iTechworld’s “Solar Power Priority” use solar first and the alternator second; Renogy defaults to the vehicle input first.

Where it can go. Engine bays get hot, wet and dusty. Redarc rates the BCDC1240D for the engine bay at up to 80°C and the Alpha 50 at IP67/69K; iTechworld’s iTECHDCDC40 is IP67 and rated for under the bonnet. Redarc’s BCDC Core is for the cabin, canopy or a battery box only, and the Dune 40A is IP20, meaning no protection from water.

Battery profiles. Every charger here lists a LiFePO4 profile. The Redarc Alpha 50 adds a separate profile for heated lithium batteries; the Dometic includes a battery temperature sensor and the Dune a temperature sensor lead.

The comparison

The Redarc BCDC1240D and Alpha 50, the Victron Orion-Tr Smart and the Renogy are listed on Amazon Australia; check the current price on Amazon. The Redarc and Victron listings we saw were from third-party sellers, so check the seller before you buy.

The picks

The Redarc BCDC1240D is the one we would have fitted. It is made in Australia, rated for the engine bay from -20 to 80°C, charges from solar and the alternator at once with solar given priority, and suits standard and smart alternators on 12V or 24V vehicles. It is $699 from Redarc with a two-year warranty.

If the charger can live inside, the Redarc BCDC Core 40A does the same job for $469: same 40A, same 9 to 32V MPPT input, same battery types, but not for the engine bay.

The iTechworld iTECHDCDC40 is the budget under-bonnet choice at $349, IP67 with solar priority and a stated 80 to 800Ah battery range. Its warranty is one year.

The Dometic 40A MPPT carries the longest warranty here, five years, and the biggest solar input, up to 800W at 37.5 to 45V. Its output is adjustable from 5 to 50A, so it suits a small battery now and a bigger one later. It is $589 at BCF ($549 Club price). BCF’s listing does not say whether it may be mounted in the engine bay.

The Redarc BCDC Alpha 50 is for big lithium banks: 50A, IP67/69K, a 48V solar window and a button Redarc says recovers a flat start battery in as little as 15 minutes, at $899.

On Amazon, the Victron Orion-Tr Smart 12/12-30 Isolated is an isolated charger with Bluetooth and a five-year warranty on the listing, but no solar input, and the Renogy 40A adds MPPT with a two-year warranty. At $149, the Dune 4WD 40A suits a battery box build with its Anderson plugs, as long as it stays dry.

A DC-DC charger or a power station?

If you would rather wire nothing permanent, a portable power station charges from the car’s 12V socket, slowly, or from a maker’s alternator charger such as EcoFlow’s 800W unit for its DELTA range. That alternator charger still connects to the vehicle’s battery, so treat it as an installation job too.

The one trap

Buying the charger on output alone and putting it in the wrong place. A cheap cabin-only charger mounted under the bonnet, or a 50A charger on a battery rated for less, will not last. Check the install rating and the battery’s maximum charge current first, then the amps. Then pay an auto electrician to fit it, and size your 12V fridge and battery together.