Countless cordless appliances such as vacuums, lawnmowers and pressure washers are ending up on the rubbish pile simply because the battery has failed or developed a fault.
In many cases, this is well before the expected end-of-life of the product. If the battery isn't replaceable, it means the whole appliance is a write-off, even if everything else is in perfect condition.
That's bad news for you, as you have to shell out for a replacement earlier than expected, and bad news for the environment, too, as it creates needless waste.
Lithium-ion batteries, the main type of battery used in cordless appliances, gradually lose the ability to hold charge over time. So not being able to replace the battery limits the usable lifetime of your product.
Some manufacturers design their products so the battery can be replaced if it fails, but not all.
As a result, Which? no longer recommends products that don't have replaceable batteries as Best Buys, regardless of how good they are otherwise.
Battery failure is one of the most common reasons why cordless products stop working.
According to our annual reliability survey, which asks owners about issues they experienced with products they bought, battery failure accounts for 52% of the reported faults with cordless hedge trimmers and 34% of the faults experienced with cordless vacuum cleaners.
Even if your battery doesn't completely die, due to the nature of lithium-ion technology, it will still gradually lose charge and you'll notice that your product doesn't last for as long as it used to.
This is rarely mentioned in the marketing spiel, though the eagle-eyed will spot that the battery is often covered separately and under a shorter warranty than the product warranty. You'll be lucky if the manufacturer covers the battery for two years - in most cases it's only one.
Not only is the warranty often shorter, but we've found a number of products, including cordless vacuum cleaners from Russell Hobbs, Vax, and Morphy Richards, where the battery cannot be replaced. So if a problem with the battery occurs, your vacuum could start to gather dust, instead of collecting it.
David Winterbottom, Vax UK Managing Director, says: 'Vax has spent the last two years investing in our new ONEPWR battery technology, a replaceable lithium-ion battery unit that provides high cleaning performance with up to 45 minutes run time, and is shareable across our new range of floor-care products.'
We also reached out to Russell Hobbs and Morphy Richards for comment, but haven't had a response yet.
As cordless products become increasingly popular, and our research shows that early battery failure is a top problem, we've tightened the rules on cordless products.
If a model does not have a replaceable battery, we won't make it a Best Buy.
Michael Briggs, head of product testing at Which?, says:
'A cordless product should last just as long as the corded one it's replacing, and a battery that can't be replaced virtually guarantees that it won't.
'We know that people love the convenience that cordless appliances offer. Our new policy on replaceable batteries means that with our Best Buys it won't be necessary to compromise on the lifetime of the product in order to enjoy the ease-of-use benefits that cordless products bring.'
This new rule will apply to the following products:
These are all products where we know the battery is one of the leading causes of early failure, and where we know from survey data that you expect a Best Buy to last longer than the battery is likely to.
The convenience of cordless products means they're here to stay, but if you want a product that lasts and doesn't leave you out of pocket, it pays to check you can replace the battery before you buy.
Our reliability survey -we surveyed 7,917 Which? members in September 2019 about the appliances they have at home. We gathered data for more than 25,000 domestic appliances.
For each product, we asked owners if and when it developed a fault, how severe that fault was and how long their previous appliance lasted before it needed replacing.