Almost every new Android flagship phone these days offers some sort of quick charging feature, but that doesn’t mean every battery powers up at the same speed. A new study reveals which devices charge the fastest, and the results may surprise you.

Tom’s Guide compared the Asus ZenFone 2, Nexus 6, OnePlus 2, Galaxy S6, LG G4, DROID Turbo and iPhone 6 in a series of tests. Initially the ZenFone seems like the clear winner, sucking up the most power in 5 minutes and again in a 15 minute trial. But the Asus phone starts to slow down the longer it charges, and ties the Galaxy S6 at 53 percent charged in 30 minutes.

The final two tests focus on how long it takes to charge the phone to a certain point, first 80 percent and then 100 percent. The Galaxy S6 wins both races, showing that it can top off your battery quicker than any other phone included in the study. The ZenFone actually drops all the way to fourth place in the 100 percent race, behind the Nexus 6, the DROID Turbo and the LG G4.

Unfortunately Tom’s Guide didn’t include the Galaxy Note 5 or Galaxy S6 edge Plus, though another recent test suggests both devices can charge pretty fast. Still, if you’re picking your next phone based on charging speeds you may want to go for the ZenFone 2. Then when you only have 15 minutes or even 5 minutes to spare you can still get the most battery power possible.

Still not convinced? Check out the full study via the source link below for even more details.