The Consumer Council says higher battery capacities do not necessarily correlate with longer battery lives in portable fans.

As the hot weather continues, the council has tested 18 models of rechargeable portable fans that come with price tags ranging from HK$58 to HK$339 for both handheld and neckband models.

It found that some models with a low battery capacity but high voltage ran longer than those with a high capacity and low voltage.

The watchdog further pointed out that a more expensive portable fan did not necessarily indicate it was of better quality or safer.

The council's director of research and survey, Angel Cheung, said more expensive models did not necessarily outperform cheaper ones.

"Actually from the results this time we can see that overall we have six models that have the highest [overall] score, which is 4.5 stars, and among these six samples we have the most expensive and also the cheapest models," she said.

Additionally, all instruction manuals were found to be inadequate – some failing to place safety instructions prominently or missing warnings for children not to play with the product.

Professor Jack Poon, chairman of the council's committee on digital economy and information technology, said consumers should select products based on what suits their needs.

"We suggest consumers don't just look at the price range... they should look at the functions."

Consumers, Poon added, should also look at the airflow of products, as well as how long it takes to charge the battery.

He calls for consumers to utilise a guide in the council's Choice Magazine that lists prices, weights, battery capacities and durations for the different portable fan models.