A Power Wheels to DeWalt battery conversion works electrically when the DeWalt pack can supply at least the motor's rated wattage, and the Power Converter handles every watt, kilowatt and horsepower comparison that the project demands. A stock Power Wheels ride-on is built around a 12V sealed lead-acid battery driving one or two small DC gearmotors, each rated somewhere between 30 and 120 watts depending on the model. The DeWalt 20V Max family runs at 18V nominal and ships in capacities from 1.5Ah compact packs up to 9Ah XR bricks, which translates to roughly 27 Wh on the small end and 162 Wh on the large end. Before any wiring is touched, the builder has to translate motor wattage into the language of the battery label — voltage, amp-hours, and continuous discharge current — and then verify that the resulting watt budget fits inside what the pack can safely deliver. Power, voltage and current are related by P = V × I, but the units a hobby motor plate lists (watts, sometimes horsepower) rarely match the units a DeWalt spec sheet lists. The Power Converter flips between watts, kilowatts, mechanical and metric horsepower, BTU/h, ft·lbf/s, cal/s and kcal/h in one place, so motor plate and battery label always end up speaking the same unit.
Why Builders Swap Power Wheels to DeWalt Batteries
The 12V SLA battery that ships with most Power Wheels weighs roughly 2 kg, takes eight to ten hours to recharge on the included wall wart, and loses capacity every winter whether it is used or not. A DeWalt 20V Max pack weighs about a third of that for a similar or larger watt-hour rating, drops into any DeWalt charger the builder already owns, and the modular format means a spare pack keeps the toy rolling while the first one recharges. For a family that already has a stack of DeWalt tools, the swap turns a forgotten shelf unit into a recycled power source.
The trade-off is electrical. A DeWalt pack sits at 18V nominal (20V max), not 12V, and its built-in protection board expects a defined continuous load. That means the motor's wattage and the battery's continuous discharge rating have to be compared in the same unit before the swap, which is where a power converter enters the build.
The Power Specs You'll Be Working With
Three numbers decide whether the conversion works:
Motor rated power. Printed on the gearbox or in the Power Wheels spec sheet, usually in watts. A stock single-motor ride-on sits in the 30–60 W range; a twin-motor 4x4 Power Wheels can pull 200 W or more under load.
Battery deliverable power. Calculated as nominal voltage multiplied by continuous discharge current. A DeWalt 5Ah pack rated at 15A continuous gives 18V × 15A = 270 W of headroom.
Energy capacity. Watt-hours are how builders compare runtime. The same 5Ah DeWalt pack holds 18V × 5Ah = 90 Wh, while a stock 12V 7Ah SLA stores 84 Wh — almost the same energy, in a third of the weight.
Because motor plates speak watts and the occasional horsepower, AC labels around the workshop speak BTU/h, and battery spec sheets speak watt-hours, a single conversion tool that ties them all together keeps the math honest.
How to Use the Power Converter for Your Conversion
- Open the Power Converter in your browser.
- Type the motor's rated wattage into the power value field — for example, 100.
- Pick the unit you are converting from (watts) and the unit you want the answer in (for example watts to hp, or watts to BTU/h).
- Read the converted result instantly, or tick "Show all units at once" to see watts, kW, MW, hp, BTU/h, ft·lbf/s, cal/s and kcal/h on a single screen.
- Repeat the same input against your DeWalt battery's continuous wattage so motor rating and battery deliverable power show up side by side in matching units.
Everything runs client-side, so no build numbers are uploaded.
Motor Watts, Horsepower, and BTU/h on the Same Page
The Power Converter uses a single base unit — the watt, defined as one joule per second. Every input is first turned into watts, then divided into the target unit, so every pairing stays consistent. The constants it works from are exact rather than approximate:
| Power unit | Symbol | Exact value in watts |
|---|---|---|
| Mechanical horsepower | hp | 745.6998715822702 W |
| Metric horsepower | PS | 735.49875 W |
| 1 BTU per hour | BTU/h | ≈ 0.293 W |
| 1 kilowatt | kW | 1,000 W |
Mechanical horsepower is the unit you see on US and UK spec sheets; metric horsepower — written PS, CV or cv — is what shows up on European and Asian data sheets. The two differ by about 1.4%, so a 100 PS motor is roughly 98.6 mechanical hp.
Worked example. A twin-motor Power Wheels gearbox is rated at 120 W. Converting to mechanical horsepower by hand:
120 W ÷ 745.7 = 0.161 hp (mechanical)
The Power Converter produces that same figure instantly and labels it as mechanical hp so it isn't quietly swapped for metric PS. Going the other way, the same 120 W input read in BTU/h works out to roughly 410 BTU/h (since 1 BTU/h ≈ 0.293 W), which illustrates how the tool keeps every unit consistent on the same page. At the extreme ends of the scale — milliwatts up to megawatts, roughly nine orders of magnitude — the converter switches to scientific notation so no significant figures are lost.
Pitfalls When Converting Power Units for Battery Swaps
Three traps catch first-time builders:
- Mixing mechanical and metric horsepower. US and UK material treats "hp" as mechanical; European and Asian spec sheets treat it as PS. They differ by about 1.4%, which is invisible on a stock gearbox and visible once a high-torque aftermarket motor is in place. The Power Converter lists both as separate units so they are never silently merged.
- Reading peak wattage as continuous wattage. DeWalt packs advertise a peak discharge current that lasts only a few seconds. The number that matters for a Power Wheels drivetrain is continuous, because the toy runs for minutes, not milliseconds. Use the converter to put both figures on the same screen in watts and the gap becomes obvious.
- Confusing watt-hours with watts. Watt-hours measure how much energy a battery stores (capacity, runtime); watts measure how much power it can deliver at one instant (load). The two are related by time but not interchangeable, and the Power Converter only converts power — not energy — so the energy side of the build still needs voltage × amp-hour math.