In order to determine the performance of power tool batteries, TÜV product testers carried drove dozens of nails into wood – among other tasks. — dpa
The basic design of power and garden tools hasn’t changed much over the years - a lawn mower is still a lawn mower.
What has changed is the batteries that power them. They have now become so long-lasting that they challenge petrol and mains-powered devices.
The reason is lithium-ion batteries. They can store a large amount of energy while remaining small and light. It also helps that manufacturers now use a standardised and therefore replaceable battery system for their devices.
That means that the same rechargeable battery fits equally well in the hedge trimmers, lawn mowers, chainsaws, cordless drills, and vacuum cleaners made by that manufacturer.
Avoid emptying the battery
Rechargeable batteries can last a long time, but there are things you can do to prolong their life. Battery packs consist of individual cells.
“It is practically unavoidable that the charging capabilities of these cells develop differently over time,” says Peter Baruschke, editor of a DIY magazine in Germany called Selbst ist der Mann.
“This is a normal consequence of use. What should not happen, however, is deep discharge.” That destroys lithium-ion batteries.
For that reason Baruschke advises using battery-powered devices regularly.
“That’s why it’s good that there are some systems where you can use the same rechargeable batteries in both garden tools and tools of the same brand. So individual rechargeable batteries can basically be used all year round,” he says.
That also can save you money when manufacturers offer devices without batteries.
“The rechargeable battery and charger sometimes make up half of the purchase price of a device,” says Baruschke. If you already have the right battery for that device you’ll be spared that expense.
Storage and charge level
In a test Selbst ist der Mann stored six batteries of common brands for 80 days at 40 degrees. That heat level can occur in small garden sheds on hot summer days. The batteries took this badly.
“Their storage capacity decreased permanently,” Baruschke says. In the worst case, up to a quarter of the charging capacity was lost in the test after only about two months.
Baruschke’s advice is to store batteries in a cool place, especially if you won’t be using them for a while: “For example, in the basement or in the apartment.”
“If the battery went flat during use and the device switched off in the process, then it’s good to recharge the battery a bit before storing it,” Baruschke says.
“Because if it were to lie empty for a long time, that wouldn’t be optimal for the battery cells. But it’s also not good to charge it up fully straightaway.”
He recommends storing rechargeable batteries at a 50% charge level and then charging them fully the day before you plan to use them. – dpa
