Cordless pressure washers run solely on battery power so their maximum runtime per charge is an important consideration before buying one. After all, nothing is more frustrating than having your machine abruptly stop working mid-way through a major cleaning job.

So what is the realistic operating time you can expect from a fully juiced up cordless pressure washer? Here’s a breakdown of the major factors that determine battery life.

Battery Voltage and Capacity

Today’s best cordless pressure washers use lithium-ion batteries with voltages typically either 18V or 20V. Some heavy duty models may even harness two of these batteries working in unison to drive an ultra high pressure motor.

But besides voltage, the other key metric that indicates potential runtime is battery capacity measured in milliamp hours (mAh). Think of capacity like the size of a bucket – the more mAh, the larger the bucket for holding charges. High capacity translates to longer running time.

Most 18V batteries used for cordless pressure washers have capacities between 2Ah to 6Ah whereas the capacities for 20V batteries range from 2Ah to as high as 10Ah.

With voltage being equal, the 20V model with a 10Ah battery inherently contains a larger “bucket” of charge than say an 18V version with just 2Ah. Therefore it can run over 5 times longer per full charge!

Average Runtime Expectations

The lowest-end cordless pressure washers armed with tiny 18V 2Ah batteries sputter out in barely 15 to 20 minutes. This might be adequate for quick small jobs like cleaning lawn furniture.

More powerful midrange models packing 20V 4Ah batteries typically operate continuously between 20 to 30 minutes on a full charge. This gives you enough juice for several car washes or cleaning medium sized outdoor areas.

Finally industrial strength cordless pressure washers equipped with ultra high capacity 20V 10Ah batteries boast the longest peak operation time between 45 to 60 minutes. That’s ample runtime to blast clean large surfaces like driveways and decks without stopping to recharge.

The Impact of Pressure Rating

Besides battery metrics, the other consideration is pressure rating measured in psi or bar. Cordless pressure washers can output anywhere from 1300 psi (20 bar) on lower end versions to 2300 psi (60 bar) on heavy duty configurations.

Higher pressure equates to increased electricity draw which then shortens potential runtime on a single full charge. So if extended battery life is important, compensate by choosing a model with lower pressure but larger capacity 20V battery. This balances cleaning power and runtime.

One Hour Sweet Spot

Given typical battery specs, most average users should expect 30 minutes as the normal per charge duration for more powerful cordless pressure washer models. Go for machines which slightly exceed the 30 minute mark since their “true” operating time will be closer to the half hour point once you factor in real world conditions.

You can effectively double your cleaning working time to a full hour by purchasing a spare backup battery. This way you always have a freshly charged one on hand. Once battery one runs out, stop to swap in battery two and resume working immediately.

In a nutshell, plan on having one to two high capacity 20V batteries to enjoy up to an hour of total cordless pressure washing without disruptive downtime!