USB Charger Fail...and then what?

[calnorth]

Feb 13, 2016 15:35:52 GMT 300 said:

Feb 13, 2016 14:56:24 GMT @broadblaster said:

I just use these (not these exact ones) but the same sort of thing son in law is a sparky so got him to get the right ones i needed.
www.screwfix.com/p/lap-13a-sp-2-gang-switched-socket-usb-charger-port-white/1204f

Looked at those they're a great idea but most seem to be 2amps or more, a little too much i thought for the Wife's I-Stick.

Thats the current output limit of both USB sockets...total of 2. Could be split 1 Amp each or similar. But your iStick won't be troubled by that.

I'd rather charge stuff by PC or Laptop though. And Screwfix bothers me..along with B&Q. but I would be! 

[Deleted]

Feb 13, 2016 15:35:52 GMT 300 said:

Feb 13, 2016 14:56:24 GMT @broadblaster said:

I just use these (not these exact ones) but the same sort of thing son in law is a sparky so got him to get the right ones i needed.
www.screwfix.com/p/lap-13a-sp-2-gang-switched-socket-usb-charger-port-white/1204f

Looked at those they're a great idea but most seem to be 2amps or more, a little too much i thought for the Wife's I-Stick.

I was also unsure so got him to make sure he got the right ones lol i did also see some of them are a max of 2a draw over the 2 ports 
so if 1 was drawing something with 0.5 the other port would only put out 1.5 if that makes sense.

[calnorth]

Feb 13, 2016 15:57:03 GMT @broadblaster said:

Feb 13, 2016 15:35:52 GMT 300 said:

Looked at those they're a great idea but most seem to be 2amps or more, a little too much i thought for the Wife's I-Stick.

I was also unsure so got him to make sure he got the right ones lol i did also see some of them are a max of 2a draw over the 2 ports 
so if 1 was drawing something with 0.5 the other port would only put out 1.5 if that makes sense.

Thats about right. That might even be a regulation limit for this stuff. Some of the SMART TVs (my Samsung) show it on their USB port labels, so you know which port power feeds and which don't,

[phatfil]

my understanding is if the device wants X ma of power at a given voltage (5V for usb) as long as the supply can provide enough or more ma then all is good so a 2a supply for an istick isnt a problem..

however when you have a device with a demand for more ma than the supply is rated for Then you can have problems as the device will try to suck more power than can be provided resulting in the supply overworking overheating and blowing/failing..

[300]

Feb 13, 2016 17:40:11 GMT phatfil said:

my understanding is if the device wants X ma of power at a given voltage (5V for usb) as long as the supply can provide enough or more ma then all is good so a 2a supply for an istick isnt a problem..

however when you have a device with a demand for more ma than the supply is rated for Then you can have problems as the device will try to suck more power than can be provided resulting in the supply overworking overheating and blowing/failing..

You're prolly right, but i always conjure up images of the lady behind the bar who's e-cig blew up 'cos she was charging it with her I-Phone charger.

Think i'll stick with my 1amp max supply.

[calnorth]

Feb 13, 2016 17:40:11 GMT phatfil said:

my understanding is if the device wants X ma of power at a given voltage (5V for usb) as long as the supply can provide enough or more ma then all is good so a 2a supply for an istick isnt a problem..

however when you have a device with a demand for more ma than the supply is rated for Then you can have problems as the device will try to suck more power than can be provided resulting in the supply overworking overheating and blowing/failing..

Thats how it works and is about a condition known as maximum power transfer. However, if you put a load on thats near enough a short circuit...things might go pop/flash! To prevent that the power unit must be able to detect that its delivering too much curent (ma/A). If the design is good it will stop that. In some designs that may be too late. Options then are...its just dead or it delivers some badly shaped power to your device...or too much!

Your vape device does the above to the various states of your heating coil...only it does it dead quick under microprocessor (sensing) control. Those USB chargere we refer to above do recovery in an old fashioned/too late kind of way.