Charging USB lights

Moonbiker
Moonbiker Posts: 1,706
edited January 2019 in Road buying advice
Are chargers all the same or are some better/faster than others?

Being using ports on computer but was looking at this on ebay:

https://www.ebay.co.uk/itm/UK-Plug-QC-3 ... 0010.m2109

claims x4 faster but then what volatage are most usb lights designed to charge at probably won't make a difference?

Comments

  • Danny1920
    Danny1920 Posts: 51
    Don't quote me but I think if you charge from the mains it's gotta be a faster charging time
    than if you connet it to the usb port on your pc
  • singleton
    singleton Posts: 2,502
    Some - perhaps even most - devices will charge faster with a higher rated power source, but some will not.
  • cq20
    cq20 Posts: 207
    Depends on the device. Some I’ve seen some warn not to charge above “standard” USB spec by which they mean 5V and 1A. Faster chargers eg iPad etc are speced at 5.2V / 2.4A. These are usually fine for charging modern mobile phones etc (and are faster). If in doubt I would stick to the standard 5V / 1A charger (some, mainly older PCs, drive their USB ports at 5V / 0.5A and that can be insufficient to power some portable external disk drives which is a real pain).
  • timothyw
    timothyw Posts: 2,482
    Sooooo.... USB always runs at 5 volts (unless we're talking about the latest fast charge/quick charge phones but I'm not aware of any bike lights that can do that), the power supplied is down to that voltage multiplied by the current supplied (the amps, or A value).

    A standard USB 2 port supplies 0.5 amps and so 2.5 watts. A USB 3 port supplies 0.9 amps, so 4.5 watts. (some computers/laptops nowadays will have a designated 'charging' port nowadays that does more but those are the standard numbers). The charger you've linked claims to do 3 amps for one port, 2.4 amps for the others (so 15 watts or 12 watts).

    So, obviously, when we're talking about up to 6 times the amount of current being supplied, that's a lot more power and so a much quicker charge.

    I would be rather wary of buying this particular charger, being so cheap it seems there is at least some chance it might be a bit more inclined to catch fire than one from a more reputable brand/supplier.

    Also not all lights will be designed to receive such a large amount of current- at best they'll charge no faster, at worst they'll get hot and damage the battery or perhaps even catch fire.

    This might sound a bit overblown, but I seem to recall that now smoking in bed is out of fashion, the most common cause of house fires is dodgy devices being charged from dodgy chargers - knock off iphone chargers and e-cigs are a notoriously bad combo.

    So yeah, if charging from a new charger, it's always a good idea to stay in the room so that you can notice if it starts smoking.

    With that said, you probably already have an old phone charger or two that supplies 2amps or at least more than one amp (phones take forever to charge from a standard usb port if you haven't noticed!) - it's worth trying it out to see if there is any actual improvement in charging speed. I suspect for most rear lights there will be very little difference, because they have such small capacity anyway - proper 'see with' front lights will probably have good speed gains available.

    Also remember that the slower the charge, the kinder it is to the battery - personally I only fast charge my big lights or if I'm in a hurry....
  • cq20
    cq20 Posts: 207
    As an update to my earlier post, I’ve just checked the instructions on one of my USB lights (made by Moon, IIRC) and it states “If using a USB mains charger please check the voltage is not greater than 5V and the output is not greater than 1.0A”.

Categories