It's one of the biggest frustrations of modern life: reaching for your smartphone to make that crucial call or vital email, only to find its battery is already flat.
But one company thinks it has the answer with technology that could mean your phone could last a week on a single charge.
British firm Intelligent Energy has been touting the potential of hydrogen fuel cell technology as the answer to your dead smartphones.
The company announced on Monday a £5.25 million ($7.6 million) project in which it is working with an "emerging smartphone" maker – which it didn't disclose – to embed the technology into the manufacture's devices.
Intelligent Energy said that hydrogen fuel cells could be embedded into a smartphone while retaining the device's existing technology, giving the handset a one week life on a single charge.
But the way hydrogen fuel cells work could pose a problem. They generate electricity from a chemical reaction between hydrogen in oxygen which then creates an electrical current, producing water as a byproduct. Just exactly how this water escapes the phone will be a key challenge to prevent soggy pockets and damaged devices.
Also, hydrogen fuel cells cannot be charged up just by plugging it into the wall. Instead, the actual hydrogen within the cell needs to be replaced, another design challenge the manufacturer will have to overcome. A disposable cartridge that can be inserted into the phone could be one way to tackle this.
Intelligent Energy and its partner will also need to find a way to reduce the cost of the technology.
Hydrogen fuel cells however have been demonstrated in other products. Intelligent Energy showed off a drone earlier this year powered by the technology while carmakers are looking at ways to integrate the power source.
But the technology has had some critics, most notably the Tesla boss Elon Musk, who last year called hydrogen fuel cells "extremely silly".
"It's just very difficult to make hydrogen and store it and use it in car," Musk said in a press conference in January 2015.
"Hydrogen is an energy storage mechanism, it's not a source of energy."