USB plugs

arcturus · Apr 14th, 2019, 09:47

Although it say on my USB plugs input 12v/24v they seem to work on 6v. Is that normal?

Army · Apr 14th, 2019, 10:39

The output for USB is meant to be 5V

You might have found something that will drop the 6V supply down to 5 for you but I'm not sure if it will be happy to do this for long if it was designed to accept 12V - check with the manufacturers (if you can)

Ron Kwas · Apr 14th, 2019, 12:38

Army; I believe the car has a 6V system and the point he is trying to make is that the converter, rated at 12/24V input, works down to 6V...

Arcturus; If converter is working at a voltage lower than it is rated for, consider yourself lucky for having gotten one with a specification tighter than actual function...don't forget, there are no 6V vehicles produced now (outside your kid's Little Tikes Jeep, and it's unlikely that it needs a USB PS), so components are probably not even tested for operation at that low voltage (there's just not much need or market!), whereas they are designed and tested for the common 12V, and the also common 24V used in heavy commercial vehicles, where there is plenty of market.
...so normal? who knows, you'd have to check other examples of the unit, but in your case, a desirable side-effect for that particular one! Remember, check operating temperature, and keep it cool as possible with heat sinking...

Cheers

SwissXC90 · Apr 14th, 2019, 12:52

Quote:

Originally Posted by arcturus

Although it say on my USB plugs input 12v/24v they seem to work on 6v. Is that normal?

Yes, normal but design dependent.
Check it at full load. If it still puts out 5V at a full 1A or 2A load (depending on what it is rated for) then consider yourself lucky.

Every voltage regulator needs a certain amount of headroom to work properly. By headroom I mean the difference between input and output voltage.
Some linear regulators will work down to 0.5V headroom, meaning for a 5V output, the input must be 5.5V or higher.
Some switch mode regulators will need less or maybe more headroom.

All depends on the design.

arcturus · Apr 14th, 2019, 13:17

I'm running a sat nav from it. Tomtom

Derek UK · Apr 14th, 2019, 23:29

If it's a USB adaptor that you have plugged into a lighter socket see if you can measure the output with a meter. Should be 5.25v.

Apr 14th, 2019, 09:47	#1
arcturus arcturus Last Online: Today 08:17 Join Date: Mar 2006 Location: Sagres Portugal	USB plugs Although it say on my USB plugs input 12v/24v they seem to work on 6v. Is that normal? __________________ life's too short to drink bad wine

Apr 14th, 2019, 10:39	#2
Army marches on his stomach Last Online: Feb 11th, 2022 03:15 Join Date: Jan 2018 Location: Somewhere in the Netherlands	The output for USB is meant to be 5V You might have found something that will drop the 6V supply down to 5 for you but I'm not sure if it will be happy to do this for long if it was designed to accept 12V - check with the manufacturers (if you can) __________________ 1961 Volvo PV544 the quick and easy in between project(!) 1981 Mercedes 300D <=> 230 diesel to petrol conversion project 1965 Series 2a Station Wagon mega build 1992 Mercedes 190E The car that works!

Apr 14th, 2019, 13:17	#5
arcturus arcturus Last Online: Today 08:17 Join Date: Mar 2006 Location: Sagres Portugal	I'm running a sat nav from it. Tomtom __________________ life's too short to drink bad wine

Apr 14th, 2019, 12:38	#3
Ron Kwas Premier Member Last Online: Today 11:51 Join Date: Jul 2007 Location: Connecticut, USA	Army; I believe the car has a 6V system and the point he is trying to make is that the converter, rated at 12/24V input, works down to 6V... Arcturus; If converter is working at a voltage lower than it is rated for, consider yourself lucky for having gotten one with a specification tighter than actual function...don't forget, there are no 6V vehicles produced now (outside your kid's Little Tikes Jeep, and it's unlikely that it needs a USB PS), so components are probably not even tested for operation at that low voltage (there's just not much need or market!), whereas they are designed and tested for the common 12V, and the also common 24V used in heavy commercial vehicles, where there is plenty of market. ...so normal? who knows, you'd have to check other examples of the unit, but in your case, a desirable side-effect for that particular one! Remember, check operating temperature, and keep it cool as possible with heat sinking... Cheers

Apr 14th, 2019, 23:29	#6
Derek UK VOC Member Last Online: Today 15:54 Join Date: Jul 2006 Location: Chatham	If it's a USB adaptor that you have plugged into a lighter socket see if you can measure the output with a meter. Should be 5.25v.

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