How to power a USB hub in a car

rizay · Newbie Joined: 28 Nov 2008 Posts: 3

I use my laptop in my car on a daily bases. It only has 1 usb port and I use about 5 usb devices. I bought a powered usb hub. It works ok without power if you only use one or two usb devices. However, when I use more devices, they don't operate correctly. And it doesn't have enough power to operate my external dvd rom. Unfortunately, the power adapter is for ac current.

I have searched for a 5v dc power supply that carries enough current to power this hub but with no luck. There are lots of 5v dc power plugs but many only hold about 500mA.

I have one of these that I was hoping I could somehow increase the mA to supply my hub:

At the bottom of the pic, it has a usb charger. It carries 5v dc at only 500mA. How can I increase the mA to supply my hub?

Alan · Posted: Fri Nov 28, 2008 7:19 pm Post subject:

500mA is common since that was the initial spec for a high power USB device. You are now able to pull more current from modern USB ports. The problem with using the plug in USB power as in your picture is that it will have no data, it will only be power. I am assuming that your dvd drive has a USB cable and a power plug.

What is your computer plugged into? I am thinking that you have 110AC power from a small inverter, if so you should just plug your dvd power supply into that also.

rizay · Newbie Joined: 28 Nov 2008 Posts: 3

My hub has a usb input that allows both data transfer, and powers the hub. It also has a 3.5mm (I think) plug for the ac power adapter. So all I'm trying to do is pull more current into the hub to power my devices.

My DVD rom has two usb cables. One for data and one for power.

I don't use an inverter. I have a dc charger for my laptop. I thought about an inverter but they waste a lot of energy on heat.

I am willing to use something else instead of this power plug. I had it lying around and noticed that it has 5v output so I thought I could somehow boost the mA.

Thanks for you input.

Alan · Posted: Sat Nov 29, 2008 1:15 pm Post subject:

Ok, you have a few options. Have a look at what voltage the hub AC adapter makes, if it is 12 volts you can simply make an adapter cable that takes your car DC power and feeds it to the barrel connector. The other thing you could do is make a 5 volt supply that can provide an amp or so of power. This should be plenty to power your devices.

Have a look at the diagram on this page. Please note that you will have to bolt on a heat sink.

http://eidusa.com/Electronics_Voltage_Regulator.htm

rizay · Newbie Joined: 28 Nov 2008 Posts: 3

That is exactly what I needed. Thank you so much.

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