Liters Not Amps

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Can a jump starter charge a phone?

Updated

Yes. All five of our picks list a USB port for charging phones and other small devices. The catch is that every phone charge uses the same battery you need to start your car, so recharge the pack after you use it as a power bank.

What each listing says

Jump starterPhone charging on the listing
NOCO GB20 and GB40Built-in power bank for phones and tablets
NOCO GBX7560 watt USB-C Power Delivery for phones, tablets and laptops. The fastest output of our picks
GOOLOO GP4000Dual USB outputs, one with fast charging, plus USB-C
GOOLOO A3Works with USB devices such as phones and tablets

How to do it

NOCO's support page gives the steps for its Boost packs: open the cap on the USB OUT port, plug in your phone's charging cable, and power on the pack. GOOLOO packs work the same basic way. Check your manual for which port is input and which is output.

Why a small gadget may not charge

GOOLOO's FAQ explains a common surprise. Its jump starter will not charge devices that draw a very small current, such as some older phones, earbuds and many smartwatches. It needs at least 200mA and shuts off after 30 seconds below that. If your watch will not charge, that is likely why, not a broken pack.

The catch: keep enough for a jump

If a laptop is part of the plan, the GBX75 is the pick whose listing names laptops. Its caveat: at 5 pounds it is the heaviest pick here. For everything else, see the five picks.

Safety: do not charge devices from a pack that is hot, swollen or damaged. Stop using it and follow the maker's disposal advice. Keep the pack away from children.