DC-DC chargers
Redarc 40 A DC-DC charger
The unit most Australian installers fit without being asked, and the one whose wiring diagrams every auto-electrician already knows.
Specifications and model checks
This profile identifies a brand and rating or model family. Confirm the precise variant and current datasheet; voltage, monitoring and environmental limits can vary between versions.
| Charge current | 40 A |
| Input | 12 V alternator, with solar input on some variants |
| Lithium profile | Yes |
| Made for | Vehicle and marine |
Suitable boat applications
A 90 A alternator feeding a 200–400 Ah bank — the commonest boat on this site.
Compatibility limits to check
You want alternator temperature sensing as standard rather than as an add-on.
For how to size this against your own boat rather than against a spec sheet, read dc-dc chargers.
Sized for your boat
40 A
Charge current for a 400 Ah bank on a 90 A alternator
This is a ceiling, not a target. A charger larger than your alternator can sustain is the failure this whole page exists to prevent, so we list what fits at or under it — biggest first.
5 options fit — the first is the one we would fit
Before choosing Redarc 40 A
Match the charger to the installed charging system
Check the input source, battery requirements and the alternator’s available continuous output under actual operating conditions. Include other engine electrical demand in the assessment. Maximum charger output is not a promise of output at every temperature or speed, and the design needs to account for control signals and protection behaviour as well as current.
Confirm specifications against the exact model and revision offered by the supplier. A listed price band is a planning reference; request a current written quote with installation and commissioning separated from equipment supply.
Compared with
The rest of the category
| Product | Charge current | Price band |
|---|---|---|
| Victron 18 A | 18 A | $230–$340 |
| Redarc 25 A | 25 A | $390–$550 |
| Victron 30 A | 30 A | $380–$540 |
| Enerdrive 40 A | 40 A | $590–$800 |
| Redarc 50 A | 50 A | $680–$920 |
| Victron 50 A | 50 A | $720–$980 |
| Victron 60 A | 60 A | $880–$1,200 |