Yard Robot Batteries Explained: Li-ion, LiFePO4, Voltage, Ah, Wh, Runtime and Charging
Battery specifications are among the easiest yard-robot numbers to misunderstand. A larger amp-hour figure does not automatically mean a robot will run longer, and an advertised runtime does not tell you how the machine will perform on a steep lawn, in wet grass, or while moving heavy snow.
This guide explains the battery terms Yard Robot Lab uses in model specifications and comparisons. The goal is to make different machines easier to compare without pretending that a laboratory number guarantees real-world runtime.
Voltage, amp-hours and watt-hours
Voltage (V) describes electrical potential. It is important to the way a machine’s motors and electronics are designed, but voltage alone is not a measure of total stored energy.
Amp-hours (Ah) describe battery charge capacity. Comparing Ah only makes sense when battery voltage is also considered.
Watt-hours (Wh) are usually the most useful first-pass measure of stored battery energy. When the necessary values are published, nominal watt-hours can be estimated as volts × amp-hours. For example, a nominal 36 V, 10 Ah battery represents about 360 Wh. This is an energy-capacity comparison, not a prediction that two 360 Wh robots will have identical runtime.
Why the same battery capacity can produce different runtimes
Runtime depends on far more than battery size. Motor efficiency, machine weight, drive system, terrain, slope, traction, cutting or clearing load, operating speed, weather and software behavior all matter. A mower working short dry grass on level ground faces a different load from the same machine climbing a hill through tall wet grass. A snow robot pushing dense wet snow faces a very different load from one clearing several inches of dry powder.
Yard Robot Lab therefore records manufacturer runtime claims together with their stated test conditions whenever those conditions are available. If the manufacturer does not publish the conditions, we say so.
Lithium-ion and LiFePO4
“Lithium-ion” is a broad family of rechargeable battery chemistries. Lithium iron phosphate, commonly abbreviated LiFePO4 or LFP, is one member of that family with different tradeoffs from other lithium-ion chemistries. Energy density, cycle life, weight, cost, charging behavior and temperature characteristics can differ by chemistry and battery-pack design.
For a yard robot, chemistry is only part of the story. The quality of the cells, battery-management system, thermal design, charging strategy and software limits can materially affect useful life and performance. YRL records the chemistry a manufacturer actually publishes rather than guessing from voltage or marketing language.
What a battery-management system does
A battery-management system (BMS) monitors and controls a rechargeable pack. Depending on the design, it can monitor cell voltage, current and temperature; balance cells; prevent unsafe overcharge or excessive discharge; and communicate battery status to the robot.
This matters because the usable capacity of a battery is not necessarily the same as its theoretical capacity. Manufacturers may reserve capacity at the top or bottom of the charge range to protect the pack. A robot may also return to its dock before the displayed battery reaches zero.
Automatic charging and autonomous operation
For autonomous equipment, charging behavior can matter as much as single-charge runtime. A robot that can return to its dock, recharge and resume an unfinished job may handle a property larger than it can complete on one charge.
For example, Yarbo currently states that its snow-removal system can automatically dock at roughly 20% battery and resume after charging to roughly 80%. Mammotion’s 2026 LUBA 3 AWD materials describe battery-management features including configurable charge limits and off-peak charging. These features should be compared separately from raw battery capacity because they affect how the machine fits into an automated workflow.
Cold weather deserves special attention
Snow-removal robots create a battery problem that lawn mowers largely avoid: they are expected to deliver useful power in freezing conditions. Cold temperatures can reduce available battery performance, while moving snow can impose a heavy mechanical load at the same time.
For snow equipment, YRL will therefore track the manufacturer’s published operating-temperature range, charging restrictions, storage instructions and cold-weather guidance separately from ordinary runtime claims. A robot advertised for winter use should not be evaluated solely from its summertime-style battery capacity numbers.
Charging time is not the whole charging story
A published “full charge” time is useful, but autonomous machines may deliberately operate within a narrower charge window. If a robot returns at one state of charge and resumes before reaching 100%, its effective turnaround time may be shorter than the published zero-to-full figure.
We also distinguish the charger or docking station from the battery itself. Replacement cost, warranty coverage and availability can differ for the battery, charger and dock.
Replaceable batteries and ownership cost
A battery is a wear component even when it is covered by a multi-year warranty. For long-term ownership, buyers should know whether the battery is user-replaceable, whether an official replacement is sold, its current price, and whether replacement requires dealer service.
YRL model files are designed to record replacement-battery price separately from the machine’s purchase price. That lets future ownership-cost calculations account for a battery replacement instead of treating the original purchase price as the only cost.
How Yard Robot Lab reports battery specifications
Our model database is designed to track battery chemistry, nominal voltage, amp-hours, watt-hours, manufacturer runtime claim and conditions, charging time, user replaceability, replacement-battery price, warranty period, operating-temperature range, source URL and the date the information was verified.
When a manufacturer does not publish a value, the model file should say Not published by manufacturer. We do not fill missing specifications with estimates merely to make a comparison table look complete.
What to compare before buying
Battery capacity matters, but it should be considered alongside the job the robot must perform. For a mower, look at property size, slopes, navigation reliability, mowing time per charge and recharge/resume behavior. For a snow robot, add temperature range, snow type and depth, traction, clearing width, charging behavior during storms and whether the machine can continue clearing throughout a long snowfall.
The most useful battery is not necessarily the one with the largest number printed on its specification sheet. It is the battery system that lets the robot reliably complete the work required on your property, with acceptable charging downtime and realistic long-term replacement costs.
Editorial note: Yard Robot Lab distinguishes manufacturer specifications from independent evidence and hands-on testing. Product specifications and software features can change. Verify current specifications with the manufacturer before purchase.
Primary manufacturer examples consulted: Yarbo Snow Blower Module; Mammotion LUBA 3 AWD; Mammotion 4G Service Terms.