Christabel Timmins and her long-term partner Tim Rhodes were staying at the Pendyffryn Caravan Park in Dwygyfylchi, near Penmaenmawr, in June, 2018, when the incident occurred.
The 60-year-old, of Higford, near Shifnal, suffered 55 per cent burns and died of multiple organ failure three weeks later in Wythenshawe Hospital.
An inquest in Ruthin heard how the couple were keen cyclists and bought electric bikes from Powabykes in Kingswinford in 2014.
Mr Rhodes said he decided to charge the lithium batteries inside their motorhome and as they were preparing for bed there was an explosion.
Mr Rhodes, who had been in the cab, managed to get out and he managed to pull Miss Timmins out the same way.
The couple were wrapped in wet blankets and taken to Ysbyty Gwynedd and Miss Timmins was later transferred to the burns unit at Whiston Hospital before going later to Wythenshawe.
On July 20, her family agreed to her life support machines being switched off. Mr Rhodes was also badly burned but has since recovered,
Recording a conclusion of accidental death, Elizabeth Dudley-Jones, assistant coroner for North Wales East and Central, said she was satisfied that the source of the fire was one of the batteries.
“This was a horrific tragedy for any family to endure,” she said.