Topic
Batteries and blades
Battery voltage, amp-hours, charge time and blades decide how long and how cleanly a cordless mower cuts. Here they are in plain metric terms.
- Energy
- Wh = V x Ah
- Cutting
- Remove at most 1/3 per cut
Watt-hours are the figure that tracks run time best: an 18 V, 5 Ah battery holds 90 Wh; a 40 V, 4 Ah battery holds 160 Wh.
Mow little and often. The RHS advises removing no more than one third of the grass height at one cut; the one-third rule calculator works out the steps.
A sharp blade cuts the grass cleanly instead of tearing it. Check the maker's manual for blade changes and sharpening.
Guides on this topic
- 18 V, 36 V, 40 V and 56 V mower batteries explainedWhat volts, amp hours and watt hours mean on a cordless mower battery, how twin 18 V systems work, and why the battery platform matters more than the number.Guide
- Mower battery platforms and bare tools explainedBattery platforms explained: why one battery fits many garden tools, bare tool versus kit, cross-brand adaptors and how to choose a system for your garden.Guide
- Lawn mower height settings and the one-third ruleWhich cutting height to use through the year in mm, how the one-third rule works, and what the numbered height positions on cordless and robot mowers mean.Guide
- How to store mower batteries over winterCharge level, storage temperature and where to keep cordless mower batteries over a UK winter, plus why a pack that will not hold charge in spring needs checking.How-to
- How to sharpen or replace mower bladesWhen to sharpen or swap a cordless mower blade, how to balance it and fit it the right way round, and how often to change robot mower razor blades.How-to
- How to sharpen hedge trimmer bladesSharpen hedge trimmer blades safely: remove the battery, clean off resin, file each tooth at the factory angle, lubricate, and know when to replace the blade.How-to
- How long does a cordless mower battery last?How long a lawn mower battery lasts per charge, worked out from watt hours and grass conditions, plus how many seasons a lithium pack usually lasts.Guide
- Cordless mower battery not chargingWhy a cordless mower battery will not charge: temperature lockouts, deep discharge, dirty contacts and faulty chargers, with safe checks in the right order.Fix
- Brushless vs brushed motors in cordless mowersBrushless or brushed motor in a cordless mower? What changes in run time, power in long grass, noise and lifespan, and when brushed is fine.Comparison
- Are lawn mower blades universal?Are mower blades universal? Why blades are model specific, how to match length, centre hole and part number, and how blade bolts are tightened.Guide