How to Choose a REDARC DC-DC Charger
REDARC make three families of DC-DC charger and they are not interchangeable. Two questions sort it out: where the unit is going to live, and how big your auxiliary battery bank is. Get those right and the rest follows.
Step 1. Where is it going?
This is the question that catches people out, because it is the one that kills a charger rather than just under-performing.
- Engine bay, chassis rail or under the bonnet - BCDC Classic or BCDC Alpha. REDARC rate all of these for engine bay installation.
- Inside the cabin, a ute canopy, a caravan or a battery box - BCDC Core, or the Alpha100 R for larger systems.
REDARC state plainly that the BCDC Core must not be mounted in an engine bay, and that the Alpha100 R and its battery monitor are not designed to operate in engine bay environments. Heat and moisture will destroy them. If in doubt, the Classic range is the one built to be potted against heat, water and dust.
Step 2. How big is your battery bank?
REDARC publish a recommended bank size for each model. Oversizing the charger is wasted money; undersizing means it never finishes the job on a driving day.
- BCDC1225D Classic 25A, 375W - REDARC suggest 75 to 200Ah
- BCDC1240D Classic 40A, 600W - over 200Ah lead acid, or over 100Ah lithium
- BCDC1250D Classic 50A, 750W - over 200Ah, and the only model with the SoftStart stage
- Alpha 25, 25A, 400W - 40 to 300Ah, solar array to 500W
- Alpha 50, 50A, 800W - 50 to 600Ah, solar array to 1000W
- Alpha100 R, 100A, 1600W - 100 to 1250Ah, solar array to 2000W, battery monitor included
Step 3. Classic or Alpha?
The Classic range does one job extremely well and has done for over a decade. The Alpha range costs more and adds things the Classic does not have: a 9 to 48V solar input instead of 9 to 32V, Bluetooth monitoring and configuration through the RedVision app, one-button recovery of a flat start battery, an adjustable input current limit that suits smart alternators and low-surplus vehicles, over-the-air firmware updates, and a wider operating range of -40C to 85C.
If none of that list matters to you, the Classic is the better buy and you should not pay for the Alpha. If you run a higher-voltage solar string, or you want to see what the system is doing from your phone, the Alpha earns the difference.
Your charger does not come with fuses
This surprises a lot of people. Every BCDC charger lists an input and output fuse rating, and REDARC state the fuses are not supplied. They must be mounted within 150mm of the battery positive terminal, and REDARC name the kit for each model.
- BCDC1225D and Core 25A - 40A fuse, REDARC FK40
- BCDC1240D, BCDC1250D and Core 40A - 60A fuse, REDARC FK60
- BCDC Alpha - depends on current and mounting location. An Alpha 50 in the cabin takes a 60A fuse; the same charger in an engine bay needs a higher rating, because REDARC require engine bay fuses to be rated above their in-cabin equivalent to allow for the heat.
- Alpha100 R - a much bigger install: 125A on the auxiliary battery and 175A on the start battery, with 42.4mm sq or 85mm sq cable.
A failed fuse holder is one of the most common faults REDARC support see on dual battery systems. A holder that does not grip the fuse properly builds heat and melts, and it usually gets blamed on the fuse. It is worth buying the matched kit rather than improvising.
Fitting and support
REDARC recommend installation by a qualified auto electrician, and keeping the cable run between the charger and the auxiliary battery under 1 metre. Every unit we sell is genuine REDARC stock carrying the full 2 year Australian warranty, dispatched from our Queensland warehouse.
Still not sure which charger suits your build? Call us on 07 5211 0841 and we will size it against your bank, your alternator and where you want to mount it.
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