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How much battery is in the box, and how long until it is full again
Updated
Listings lead with volts: 40V, 56V, 60V. Volts alone say nothing about how long the mower runs. The energy in the box is volts times amp-hours times the number of batteries. On the six picks here it runs from 160 to 480 label watt-hours, a 3.0 to 1 spread.
The sum
The FAA's battery page gives the rule in one line: to get watt-hours, multiply the battery voltage by the amp hours. A 56V 6.0Ah battery is 56 x 6 = 336 Wh. Two 60V 4.0Ah batteries are 60 x 4 x 2 = 480 Wh. We use the volts printed on the label. Label volts are often a peak figure, so the true energy is somewhat lower, but the comparison between kits still holds.
| Mower | Battery in the box | Label watt-hours | Claimed runtime | Average watts the claim implies |
|---|---|---|---|---|
| EGO LM2114 21 in push | 56V 6.0Ah | 336 Wh | 55 min | 367 W |
| EGO LM2114SP 21 in | 56V 6.0Ah | 336 Wh | 50 min | 403 W |
| Greenworks 60V 21 in SP | 2 x 60V 4.0Ah | 480 Wh | 60 min | 480 W |
| Greenworks 40V 16 in | 40V 4.0Ah | 160 Wh | 40 min | 240 W |
| WORX WG779 14 in | 2 x 20V 4.0Ah | 160 Wh | 40 min | 240 W |
| LawnMaster 19 in | 2 x 24V 4.0Ah | 192 Wh | 40 min | 288 W |
- EGO LM2114 21 in push336 Wh
- EGO LM2114SP 21 in336 Wh
- Greenworks 60V 21 in SP480 Wh
- Greenworks 40V 16 in160 Wh
- WORX WG779 14 in160 Wh
- LawnMaster 19 in192 Wh
The last column is watt-hours divided by claimed hours. It is the average power the mower could draw and still hit its claim. A low figure means the claim assumes easy going. Two kits here have the same 160 Wh and the same 40 minute claim, the Greenworks 40V 16 in and the WORX WG779 14 in, yet one claims 1/3 acre and the other 1/8. That is the acre problem in one line.
Two batteries: together or one after the other
The WORX and LawnMaster run on two small batteries at the same time. Both must be charged, and both come in the box. The Greenworks 60V also comes with two. Greenworks' runtime figure of up to 1 hour is for both batteries.
Recharge time is the hidden cost of a small battery
If the lawn needs more than one charge, the recharge time decides your afternoon. EGO says the 6.0Ah battery takes about 80 minutes on the 320W charger in the LM2114 kit. Greenworks says the 60V kit's dual port charger fills both batteries in 80 minutes, 40 minutes each. Greenworks lists 120 minutes for the 40V 4.0Ah battery with its included charger. A second battery turns that wait into a swap.
Platform lock-in
A mower battery fits that maker's tools at that voltage and nothing else. EGO says the mower works with all its 56V ARC Lithium batteries. Greenworks 40V, 60V and 80V batteries do not swap with each other. If you already own a trimmer or blower, check its battery first. A mower is the biggest battery you will buy, so it often sets the platform for the rest of the shed.
When the battery is finished
The EPA says lithium-ion batteries should not go in household garbage or recycling bins. Take them to a battery recycling or household hazardous waste drop-off, and tape the terminals or bag each battery on its own first.
Work out your own lawn with the mowing time calculator, or compare all six picks on the roundup page.