48V to 12V Voltage Reducer DC-DC Step-Down Converter
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Step-Down Only. 48V in, 12V Out, Never Back.
A 48V bank makes sense for storage — thinner cable, lower current, less loss over a long run. The trouble starts the moment you want to use the power. Lights, water pumps, fridges, radios, bilge pumps, nav gear and winch controls are all 12V. Wire a 12V accessory straight onto a 48V bank and you damage it in seconds.
This is a Daygreen DC-DC buck converter that sits between the 48V bank and the 12V side and holds the output at 12V. Seven current ratings, 5A (60W) through to 60A (720W), so you size it to the load rather than buying more than you need. The supplier quotes output accuracy of ±1.5%, line and load regulation of ±0.2%, and typical efficiency of 93–95% depending on the rating.
What it is not is a charger, a battery management system or a backup supply. It converts, and that is all it does. The Limits tab spells out the rest — read it before you order, because the input range and the cooling are where most people get caught.
What it Solves
- 48V House Bank, 12V Loads: the shack or shed runs a 48V bank and an inverter, but the lights, pumps and radio are all 12V and need their own supply.
- Site & Farm Machines: a 48V utility vehicle, sweeper or scissor lift where the beacon, work lights and two-way still run on 12V.
- Telecom & Remote Cabinets: 48V is the standard for comms racks, so a 12V camera, router or gate motor needs a converter rather than its own battery.
- Boats with a 48V Bank: a 48V thruster or trolling bank, with the nav lights, sounder and VHF sitting on the 12V side.
- Vans & Caravans on 48V Lithium: keeps the existing 12V fitout intact instead of rewiring the whole van when you go up to a 48V bank.
Key Features
- Seven Current Ratings: 5A, 10A, 20A, 30A, 40A, 50A and 60A, which is 60W up to 720W at 12V. Pick the rating on the Current selector.
- Tight Output Regulation: ±1.5% output accuracy and ±0.2% line and load regulation, per the supplier's figures.
- Efficiency 93–95%: typical figures from the supplier data sheet, varying by rating — the 40A unit is quoted highest at 95%.
- Three Protections Built in: over-current, over-voltage and over-temperature shutdown.
- No Fan to Fail: free air convection cooling, so nothing spins, but it does need airflow around the case.
- Three, Four or Five Terminals: depending on the model — common negative, separate negatives, or a fifth ACC terminal.
- ACC Ignition Switching: on the five-terminal units, ACC is an enable line, so the converter only runs when the ignition or a switch is live. Bridge ACC to Input+ if you don't want that.
- Surface Mountable Case: flanged aluminium housing designed to bolt to a bulkhead, panel or rack shelf.
- Low Temperature Drift: ±0.03% per °C temperature coefficient.
- Size Scales with Rating: from 66 × 59 × 24 mm at 280 g up to 150 × 127 × 63 mm at 1600 g — check clearance before you buy the big one.
Where This Fits
This is one part of the gear that sits between a wind turbine and your battery bank. Here's the whole picture:

What Else you'll Need
- Wind Turbines: vertical and horizontal turbines from 300 W to 5 kW (rated) — and they can charge overnight, when your solar can't.
- Hybrid MPPT Controllers: you can't wire a turbine straight to a battery. The controller rectifies the output, manages the charge, and brakes the turbine when the bank is full.
- A Breaker on Each Side: this converter wants protection on the 48V input and again on the 12V output, because the output side can pull five times the current for the same watts. A manual-reset breaker doubles as the switch you use when you want it dead.
- A Battery Isolator: so you can pull the whole 48V bank down before you go anywhere near the terminals. Working live on a 48V bank is how people get hurt.
- A Bus Bar for the 12V Side: once you have 12V you usually have five or six things wanting it. Landing them all on the converter's own terminals is a mess and a loose connection waiting to happen.
- Cable & Lugs: flexible copper cable and pure copper terminals to make the joins properly. Crimped and sized right, not twisted and taped.
- The Rest of the Electrical Range: bus bars, breakers, isolators, cable, lugs and Anderson plugs.
Here is the part we cannot do for you. Cable sizing depends on your run length, your voltage and your current, and the 12V output side of this converter carries four times the current of the 48V input side for the same power — a 60A unit is moving 60 amps out. Our range suits 48V and shorter runs. If you are building on 12V or 24V, work the sizing out against your own run or ask your sparky. We are not going to guess it for you.
Limits
The honest list of what this will not do. None of this is in the marketing copy, so it is here instead.
- It will Not Step Up: every unit here is 48V in, 12V out. There is no step-up model in this listing, so it will not run 48V gear from a 12V battery. If you need to raise voltage, this is the wrong part.
- It is Not a 24V Converter: only the 5A unit accepts down to 18V. The 10A and everything larger want a minimum of 30V at the input. Do not buy a 20A expecting it to run off a 24V bank.
- There is a Ceiling at 60 Vdc: and a 48V bank sits well above 48V while it is charging. A flooded lead-acid bank on an equalise cycle can push past 60V. Check what your charger actually puts out at the top of its cycle, and if it can exceed 60V, ask your sparky before you wire this in.
- It is Not a Battery Charger: it holds a regulated 12V. That is not a charge profile, so it will not properly charge a 12V battery on the output side. It is there to run loads.
- It is Not a BMS or a UPS: no cell monitoring, no low-voltage cut-off for your bank, no backup when the input drops out. When the 48V side goes, the 12V side goes with it.
- No Fan Means it Needs Air: free air convection only. Run one flat out in a sealed box with no clearance and the over-temperature protection will shut it down. That protection is doing its job, not failing.
- We Cannot Confirm a Waterproof Rating: the supplier calls the case sealed but quotes EN 50498, which is an automotive EMC standard and says nothing about water or dust. There is no IP rating on this product. Mount it out of direct weather and spray.
- Input-to-Output Isolation is Not Stated: the supplier does not say whether input and output share a ground. If your installation depends on an isolated output, do not assume this gives you one.
- No Australian Approval is Claimed: the supplier's images carry CE, FCC and RoHS marks. We have sighted no certificate, and no RCM registration or AS/NZS listing has been verified. Say so to your sparky rather than assuming.
- We will Not Size your Cable or your Fuse: that depends on your run and your load, and getting it wrong is a fire. Fit fusing on both sides sized to your cable, and ask a licensed electrician if you are not certain.
Q & A
Which Current Rating do I Need?
Add up the continuous 12V current of everything that will run at the same time, then leave headroom for start-up surge on motors, pumps and compressors — those can draw several times their running current for a moment. A 30A unit gives you 360W at 12V. If you land close to the limit, go one size up. A converter run flat out with no airflow gets hot, and the over-temperature protection will shut it down mid-job.
What Input Voltage does it Actually Accept?
It depends on the rating, and the supplier's own material disagrees with itself. The body copy says 30–60V across the board. The data sheet lists 18–60 Vdc for the 5A and 30–60 Vdc for the 10A through 60A. We have published it per rating in the Specs tab rather than pick one range and hope. Watch the top of the range as much as the bottom — 60 Vdc is the ceiling, and a 48V bank on charge sits a long way above 48V.
Does it Need a Fuse, and Where?
Yes, on both sides, and sized to your cable rather than to the converter. Some units in this range ship with a small inline blade fuse next to the terminals — you can see it in the supplier photos. Do not treat that as your system protection. It protects the converter, not your wiring. Fit your own fusing and an isolator on the 48V input and on the 12V output, and if you are not confident sizing them, ask your sparky.
Which Way Round does it Wire, and What is the ACC Terminal?
Terminals are labelled on the case. Three-terminal units share a negative; four-terminal units have separate input and output negatives; five-terminal units add ACC. Input+ and Input− go to the 48V bank, Output+ and Output− to the 12V load — get that backwards and you will destroy it, so check the legend before you tighten anything. ACC is an enable line: run it to the ignition or a switch and the converter only works when that circuit is live, which stops it drawing from the bank while everything is parked up. If you want it running permanently, link ACC to Input+.
How Should I Mount it, and How Hot does it Get?
Bolt it through the flanges to something solid — a bulkhead, a panel or a rack shelf. The metal case is the heat sink, so the fins want clear air around them and ideally the fins facing up. No fan means no noise and nothing to seize, but it also means it relies entirely on convection. Do not bury it in insulation, do not box it in tight, and keep it off timber and away from anything that minds heat.
What Happens if I Overload it?
The supplier lists over-current, over-voltage and over-temperature protection, so in normal use it should shut down rather than let go. That is a safety net, not a running strategy — a converter that keeps tripping is undersized, and repeatedly cooking it will shorten its life. Size it for the real load with headroom and it should never see the protection at all.
Some of the Photos Say 13.8V — Which One am I Getting?
Fair question, and it is our gallery that causes it. Daygreen builds this converter in a 12V line and a 13.8V line, and a few of the supplier photos in the gallery are from the 13.8V range. Every variant sold on this page is the 12V version — that is what the Current selector lists and that is what ships.
How Long does Delivery Take, and What does it Cost?
Free Standard Delivery. Allow 5 to 10 working days from the day you place your order — that is from the order, not from the day we dispatch it. Allow 1–2 days for fulfilment. Regional and remote addresses take longer again.
Specs
| Specification | Detail |
|---|---|
| Brand | Daygreen |
| Converter Type | DC-DC buck (step-down) converter. Step-down only — no step-up function. Input-to-output isolation is not specified by the supplier. |
| Input Voltage Range | Varies by rating — 18–60 Vdc on the 5A, 30–60 Vdc on the 10A to 60A. See the per-rating table below. Supplier body copy states a single 30–60 Vdc range, which conflicts with its own data sheet. |
| Maximum Input Voltage | 60 Vdc on every rating. A 48V bank sits well above 48V while charging — check your charge and equalise voltage against this ceiling. |
| Output Voltage | 12 Vdc. Daygreen also builds a 13.8 Vdc version of this converter, which is not what is sold here — some gallery photos are from that range. |
| Output Current | 5A, 10A, 20A, 30A, 40A, 50A or 60A — selected by variant |
| Maximum Output Power | 60 W to 720 W, by Rating |
| Output Voltage Accuracy | ±1.5% |
| Line & Load Regulation | ±0.2% |
| Temperature Coefficient | ±0.03% per °C |
| Efficiency (Typical) | 93–95%, by Rating |
| Ripple & Noise | 120 mVp-p on the 5A to 30A, 150 mVp-p on the 40A to 60A |
| Protections | Over-Current, Over-Voltage, Over-Temperature |
| Cooling | Free Air Convection, No Fan |
| Case | Finned Aluminium, Flanged for Surface Mounting |
| Wiring Configurations | Three, four or five terminal depending on model; five-terminal units add an ACC enable input. Which rating ships in which configuration is not specified by the supplier — the terminals are labelled on the case. |
| Inline Fuse | Some units in the range carry a small blade fuse beside the terminals. Not specified by supplier per rating, and not a substitute for system fusing. |
| Dimensions | 66 × 59 × 24 mm to 150 × 127 × 63 mm — see per-rating table |
| Net Weight | 280 g to 1600 g — See per-Rating Table |
| Ingress Protection (IP) Rating | Not specified by supplier. The case is described as sealed, but the only standard quoted is EN 50498, which covers automotive EMC and is not an ingress rating. |
| Operating Temperature Range | Not Specified by Supplier |
| No-Load / Standby Current | Not Specified by Supplier |
| Terminal / Cable Size | Not Specified by Supplier |
| Compliance | Supplier images display CE, FCC, RoHS, WEEE and SASO marks. No certificate has been sighted, and no RCM registration or AS/NZS listing has been verified. |
| Warranty | Not specified by supplier for the ratings sold here. Your rights under Australian Consumer Law apply. |
By Current Rating
Figures below are the supplier data sheet rows matched to the ratings we sell. Everything is 12 Vdc output.
| Rating | Input (Vdc) | Max Power (W) | Efficiency (Typ) | Ripple (mVp-p) | Size (mm) | Weight (g) |
|---|---|---|---|---|---|---|
| 48V to 12V 5A | 18–60 | 60 | 93% | 120 | 66 × 59 × 24 | 280 |
| 48V to 12V 10A | 30–60 | 120 | 93% | 120 | 74 × 74 × 31 | 280 |
| 48V to 12V 20A | 30–60 | 240 | 94% | 120 | 74 × 74 × 31 | 650 |
| 48V to 12V 30A | 30–60 | 360 | 94% | 120 | 100 × 80 × 39 | 500 |
| 48V to 12V 40A | 30–60 | 480 | 95% | 150 | 100 × 113 × 35 | 650 |
| 48V to 12V 50A | 30–60 | 600 | 94% | 150 | 150 × 127 × 63 | 1600 |
| 48V to 12V 60A | 30–60 | 720 | 94% | 150 | 150 × 127 × 63 | 1600 |
Wiring
Three Terminal: Input+ to battery positive, Input− to ground. Output+ to load positive, Output− to ground.
Four Terminal: Input+ to battery positive, Input− to battery negative. Output+ to load positive, Output− to load negative.
Five Terminal: as per four terminal, plus ACC to the ignition or a switch. ACC is an enable line — when that circuit is off, the converter does not run, so it isn't drawing from the bank while the vehicle is parked. If you don't want the ACC function, link ACC to Input+.
Isolate the bank before you start, check the terminal legend on the case before you connect anything, fuse both sides to suit your cable, and check the sizing against your own run length or ask your sparky.
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Wind Turbine FAQs
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- Start with two questions: how much wind your site actually gets, and how much room you have.
- Vertical turbines (the X-300, H1000 and H2000) start turning at 2 to 2.5 m/s and take wind from any direction, so they keep working where the wind swirls and shifts — around buildings, trees and rooflines. They run from 300 W up to 2000 W.
- Horizontal turbines (M-400, M-600, M-800, and the L1, L2 and G series) want cleaner, steadier wind and a clear run at it. In clean, steady wind a horizontal of the same rating is usually the better harvester, and they scale further — 400 W up to 5000 W.
- Match the turbine to your battery bank, not to the biggest number. 12 V suits a camper, 4WD or tinnie; 24 V a van, cabin or boat; 48 V a shed or remote block.
- The largest models run at mains voltage, and the L2-3000, G-3000 and G-5000 are ground-mount only — they need a 10–15 m mast and are not rooftop units.
- Rated power is measured at 10–14 m/s, depending on the model. What you get at your place depends on your wind, your mast height and the season — not on a number on our website.
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- No. Wind turbines generate "wild" 3-phase AC power that changes voltage constantly with the wind speed.
- Connecting it directly to a battery or a standard solar inverter will destroy your equipment.
- You must wire the turbine into a dedicated wind charge controller (pure-wind or wind-solar hybrid) with a dump-load resistor.
- The controller converts the power to stable DC to charge your batteries safely.
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Match the turbine and its controller to the voltage of your existing battery bank:
- 12 V: compact mobile setups — caravans, 4WDs and camper trailers.
- 24 V: medium setups — off-grid sheds, cabins and motorhomes.
- 48 V: most of this range, and the sensible choice for a full off-grid system. Higher voltage means less current in the cable, so less loss over a long run and lighter cable.
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- When your battery bank is fully charged it stops accepting power.
- If a storm hits at night with the batteries full, a turbine with nowhere to send its power will free-spin out of control and can physically fly apart.
- The controller prevents that by diverting the excess into the dump load resistor, which burns it off safely as heat and acts as an electronic brake to slow the turbine down.
- Yes, you need one.
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- Usually quieter, but not silent — no turbine is.
- Why a Horizontal is Louder: its blade tips travel several times faster than the wind, and blade noise climbs steeply with tip speed. The whoosh rises and falls as each blade comes round — a rhythmic swish that carries through wind noise more than a steady hiss does.
- Why a Vertical is Usually Quieter: its blades turn more slowly, so there is less of that whoosh.
- What we won't Tell you: that it's silent. Every turbine gets louder as the wind picks up. The wind often covers much of it in a strong blow, but a close neighbour can still hear one in light to moderate wind.
- The manufacturer publishes no noise figure for the turbines themselves (the "65 dB or less" on some Specs tabs is the controller's), so we don't quote one.
- On a building, use vibration isolators — a turbine bolted to a structure carries its sound into the rooms — and check your council's rules on noise, height and placement before you order a mast.
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- It will turn, but turning is not charging. The blades start turning at 2 to 2.5 m/s (about 7 to 9 km/h) — a light breeze.
- Charging starts at the cut-in speed: 3 m/s (about 11 km/h) on every model except the X-300, which starts and charges from 2 m/s. Output then climbs steeply with wind speed.
- The rated figure is measured much higher — 10 to 14 m/s depending on the model, a 36 to 50 km/h wind, not a normal afternoon. Each product page's spec table gives that model's own numbers.
- A gentle breeze keeps the turbine ticking over; it takes real wind to push real power into your batteries. Every horizontal model has its measured power curve published on its product page — work from that, not from the number in the product name.
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- No — small turbines are built to spin fast. The smaller the rotor, the faster it has to turn to keep its blade tips up with the wind: the M-400's 1.35 m rotor runs at about 800 rpm, the M-600 and M-800 at about 500, the big G-series at 300.
- In the manufacturer's words, the high rpm is a design necessity, not a defect. A slower generator would need a bigger stator and more magnets and copper — heavier and dearer.
- They start turning at 2 to 2.5 m/s and make power right across the wind range — just less when the wind is light. What you get depends on your site and how high you mount it.
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- Yes — connect the turbine to a battery bank first, through a dedicated charge controller.
- Never straight to an inverter. Connecting a wind turbine directly to a standard inverter will damage the equipment or cause the system to fail.
The Correct Order:
- 1. Wind Turbine — generates wild, fluctuating 3-phase AC as the wind changes.
- 2. Hybrid or Wind Charge Controller — converts it to steady DC, and protects the turbine from over-speeding with an electronic brake.
- 3. Battery Bank (12 V, 24 V or 48 V) — absorbs the gusts and provides a steady source of energy.
- 4. Off-Grid Inverter — connects to the battery, converting stored DC into AC for your appliances.
Why you Cannot Skip the Battery:
- Unstable Voltage: wind changes second by second. Without a battery to smooth it out, a direct-connected inverter would constantly cut out.
- Turbine Damage: when a battery is full or disconnected, the turbine loses its load. Without that resistance the blades can spin out of control in high wind and destroy the unit. The controller uses the battery connection to dump excess power and slow it down.
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- This turbine generates 3-phase AC power and cannot be connected directly to a battery, a solar controller or a home inverter.
- It must run through a dedicated wind charge controller (pure-wind or wind-solar hybrid) with a dump-load resistor. The dump load stops the turbine over-speeding and destroying itself in high winds once your batteries are full.
- Installation and commissioning must be carried out by a suitably qualified and licensed electrician.
- Cable, breakers, isolators and all protective devices are selected to suit your site and are the electrician's call, not ours.
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It is almost always one of three installation issues. Check them in order.
Quick Checks — Tick as You Go
- Is the Meter Set to AC Volts (V~)?
- Does it Spin Freely Once Disconnected from the Controller?
- Is the Cable from the Mast Heavy Enough for the Run?
1. The Multimeter is Set to DC — The Most Common Mistake.
- Measuring the three turbine wires with the meter set to DC volts gives a false reading near zero.
- Wind turbines generate 3-phase AC directly from the stator. Switch the meter to AC volts (V~).
2. The Turbine is Stalling Because of a Short.
- The blades turn heavily and slowly, or lock up: if any of the three AC output wires touch each other, or the controller's braking diodes have short-circuited, it acts as a magnetic brake — the turbine can never spin fast enough to build voltage.
- Disconnect the turbine from the controller. If it frees up and spins much faster, the problem is a short in the wiring or a faulty controller.
3. Voltage Drop from Thin Cable.
- Thin solar or automotive cable over 20 metres or more loses the power as heat before it reaches the controller.
- Use heavy cable between the mast and the controller on long runs — minimum 8 AWG, ideally 6 AWG. Final sizing is your electrician's call.
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- The number in the name is a peak rating, not a promise.
- A turbine's rated output is measured at a specific wind speed — 10 to 14 m/s depending on the model, which is about 36 to 50 km/h — and most sites see far less than that most of the time.
- Your display shows what the wind is delivering right now, so it will sit well below the rated figure and move second by second as the wind changes. That is physics, not a fault.
- As an example, the L2-2500 is rated 2,500 W at 11 m/s. On a decent steady coastal breeze of 7 m/s the manufacturer's own curve gives about 813 W. That is why we publish the full power curve on every horizontal turbine's product page.
- Where these machines earn their keep is time: they keep charging through the night and through the weather that shuts solar down.
- If the display shows 0 W while the blades are spinning, that is a different problem — see the 0 W question.
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- Not necessarily — this is one of the most common questions we get, and it is rarely a faulty unit.
- It is usually a quick settings check, or (on a first-time install) how the wiring and start-up sequence were done.
- See our full Wind Turbine 0W Troubleshooting Guide for the complete walkthrough, or the Set-Up Guide — or contact us and we will help you sort it out.
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- Wire your bus bar and breakers before and after the controller, then power up in the right order. Getting the sequence right prevents almost all wiring issues, including the common "spinning but 0 W" problem.
- Fit a breaker before the controller (turbine/solar side) and after it (battery side), landing on a DC bus bar.
- Keep the turbine-to-controller cable run to 2–10 metres to limit voltage drop.
- Power up in this order: battery breaker first, then solar, then wind turbine last.
- See our full How to Install & Start Up guide for the complete step-by-step walkthrough and wiring diagram.















