Dear Jim: I am tired of the maintenance for my old gas lawn mower. I might buy a rechargeable cordless mulching one. Are they powerful enough for a normal yard and what features are best? — Marcia H.
Dear Marcia: I have used cordless lawn mowers for many years and I would never switch back to a gasoline mower for my one-half-acre yard. Each generation of new designs has offered more features and power. The newest ones use lithium-ion batteries with special motor circuitry to provide more cutting area per battery charge.
Cordless mowers require no maintenance other than sharpening the blade periodically as you should do with a gasoline mower. A sharp blade does more than just reduce the power needed to cut through the grass. It also makes a cleaner cut on each blade of grass. This is healthier for the grass.
The operating cost for a cordless mower is low. There is no gasoline or oil to buy, no air filter to replace or visits to the mower repair shop. It uses less than 10 cents of electricity to recharge the battery.
When selecting a mower, first consider the size of your yard. Most cordless mowers range in cutting widths from about 14 inches to 20 inches. For a small yard or one with tight, narrow areas, a 14- or 16-inch size is good. For most homes, a 19- or 20-inch size is effective and convenient to handle.
Many newer cordless mowers use lithium-ion batteries because they are lightweight and can be recharged in just one to three hours. Models with older-type lead acid batteries can weigh up to 20 pounds more and take overnight to recharge.
Most cordless mowers with lithium-ion batteries are not self-propelled because they are not difficult to push. The new Black & Decker 20-inch model weighs only 48 pounds. For hilly yards, there are variable-speed, self-propelled models.
The amount of energy the rechargeable battery pack can store, and thus how much grass it can cut, is a function of (A) the battery voltage and (B) the ampere-hours. Multiply (A) times (B) to compare various models. If you have a large yard and will need to recharge the batteries to finish, also consider the recharging time.
For my yard, I use a 60-volt Black & Decker Power Swap model. Instead of using one big battery, it holds two removable half-size ones. When the grass is very thick during spring and one charge will not cut it all, I charge one battery while the other one runs the mower. This allows me to cut the entire yard nonstop.
Look for a model with load-sensing motor controls. When cutting thinner grass, it spins slower to draw less electric current. When it senses heavy grass and more cutting load, it powers up to the maximum safe blade tip speed. Also, look for an "edge-design" mower to be able to cut very close to trees and walls.