This is what I recently started using. So far, it seems to keep up with the battery discharge on my S4 while using the navigation. The other reason I got this is that it will charge i devices as well. I have friends with iphones and this lets two different devices charge at the same time.
Amazon.com: Anker? 24W Portable Dual-Port USB Car Charger with PowerIQ™ Technology with [Built-in Micro USB Cable for Galaxy S5 S4; Note 3 2; HTC One (M8)] and [USB Port for iPhone 5S 5C 5; iPad Air mini] (No Lightning cable included) (White):
Just bought the Anker also, what are you guys using for the cable? Purchase a usb 3.0 cable or just a standard 2.0 mini usb? I don't want to restrict the power flow!
2.0 mini, with the car charger, 2 usb angel one not The one with the coiled cord.
I also use a 2.0 cable with the original charger. Still charges very fast about 1% per minute.
Old car charger was only 1a and didn't do well with the s5 compared to the original. The anker car charger is as fast as the home charger. Also have their 5 port 25$ ac charger, that thing is great too!