I recently bought a new qed , 2 weeks later we have lockdown for who knows how long. What is the best way to maintain these batteries ? Cheers & stay safe.
Using the QED voltage meter charge them to around 3.6 to 3.8v per battery. This gives them a state of charge of about 40-50%.
Remove them from the QED & store in a cool, dry place.
Maybe check every other month & top up if required but li ion batteries can last up to 10 years like that.