The Anker 24W Dual USB car charger works great. August used it driving to and from Milwaukee for nearly 5 years and it is reliable, simple and just plain works. We have one in the van too. Some new smartphones like the iPhone and Samsung draw a lot of wattage. This little charger can reasonably handle them providing 4.8 amps to one device or 2.4 amps per port (NOTE it doesn't work with Qualcomm quick charge). Also having two ports instead of one is nice. We use both ports to charge a 2nd phone, a headset or other USB device.
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