Toybox: portable batteries for smartphones

This chunky 188 gram, 114x93x25mm Patriot FUEL+ (top left; ebuyer.com, HK$685) is equipped with a huge 9000 mAh battery that can simultaneously charge two smartphones twice over. It takes about five hours for a full charge, using a micro USB cable. With an iPhone lightning cable, it'll juice an iPhone at the standard 1 per cent per minute speed. Great for long-haul travel, the FUEL+ can recharge an iPhone 5S five times over, while its two-amp USB slot will just about completely charge an iPad Air, or about 80 per cent of an older iPad 4.

By far the smallest portable battery around, the Fuel Micro Charger (top right; expansys.com.hk, HK$199) comes with caveats. Weighing a puny 19 grams, this tiny 38x27x13.5mm jerry can-styled device is perfect for handbags and shirt pockets, but it only adds about 10 per cent to an Android smartphone, which takes about 10 minutes. An iPhone-friendly Lightning adaptor is promised soon; for now it's equipped only with micro USB slots. Strictly for Android emergencies only.

PocketCell Duo (above; payeasy.com.tw, HK$766) has two USB outputs. Weighing 132 grams, the 94x43x23mm device takes three hours to charge its 6800 mAh battery via micro USB. It's good for about four charges of an iPhone 5S, a complete refill of an iPad Mini, and can take an iPad Air and iPad 4 to about 70 per cent and 50 per cent, respectively. A novel flip-top cable is included, with built-in click-on adaptors for mini USB, micro USB and Apple's 30-pin connector (for iPhone 4S and earlier models).