12VDC USB Hubs

[casm]

I've been doing some Googling on this with little luck, so am hoping someone here may know of something offhand that fits what I'm looking for. What I'm trying to find is a 4-port powered USB 2.0 hub that takes 12VDC in from its adapter; power output over USB should be the standard 500ma figure.

The problem I'm running into is that while I can find a bajillion chargers that plug into the cigarette lighter, none of them are designed to handle data - they just charge whatever device is plugged into it. That is part of the equation here, but I want to be able to also run data over the same wiring. The other problem with those (if one were to hack it to power a hub) is that some of them output up to 2A of power over USB, which could be really disastrous to feed into a device expecting 500ma.

There are devices out there that are designed to handle this, but the cheapest one I'm finding (here), while a perfect match, is $85 - and the prices for stuff like this only seem to go up from there. There're also items like this one, but the description is nebulous as to what its input voltage actually is.

So... Does anyone have a USB hub sitting on their desk that matches what I'm looking for? I realise I could build an external power regulator for one, etc. but would prefer to keep to a single-box installation on this partly for the sake of tidiness, but also to eliminate potential points of failure.

 

[dave92cherokee]

The other problem with those (if one were to hack it to power a hub) is that some of them output up to 2A of power over USB, which could be really disastrous to feed into a device expecting 500ma.

You're not thinking about it correctly. Think about it like a high output alternator, just because it has the ability to put out 160A doesn't mean that it always will. Same with the adapters if the device only needs 500mA then that's all it will draw off the charger. If you have a charger that's able to put out up to 2A then it will have plenty of power to run any USB devices. Just need to make sure that the USB hub is designed to take the 12V as USB power is 5V DC.

 

[Johnnie Walker]

In thoery you can use any usb hub, just get a Cig lighter adapter that outputs the correct voltage/amperage.

 

[casm]

You're not thinking about it correctly.

Not quite - it's more that I didn't describe the issue clearly More:

Think about it like a high output alternator, just because it has the ability to put out 160A doesn't mean that it always will. Same with the adapters if the device only needs 500mA then that's all it will draw off the charger. If you have a charger that's able to put out up to 2A then it will have plenty of power to run any USB devices.

All of the above is correct. However, what I was trying (poorly) to say was that if I modify a USB lighter adapter to supply power over the USB hub and that lighter adapter can output more than 500ma, it will supply more than 500ma if a device attached to the hub needs it. Which is fine for that device, but I'd effectively be feeding that same amperage to all devices on the hub, some of which may not cope well with that much current - and that assumes that the hub itself can handle it.

Hope that clears up where I was coming from on all of this; my initial explanation was p***-poor in that regard.

Just need to make sure that the USB hub is designed to take the 12V as USB power is 5V DC.

Yep, which is why I'm looking for a hub that can take 12VDC in and step it down internally to 5VDC for USB. Still trying to find something that fits, but the $85 box may end up being the most realistic option (in which case all of this can be filed under 'eventually').

In thoery you can use any usb hub, just get a Cig lighter adapter that outputs the correct voltage/amperage.

That's part of the problem as well - trying to find one that just does 500ma is proving tricky. Because they're being used to charge phones, etc. most of them run at higher amperages to cut down the charging times. But my GPS (for example) can't charge its batteries when connected to USB so only expects 500ma into it. Really don't want to find out what happens if that suddenly cranks up to 1.5A because I plugged my phone into the hub at the same time :scared:

 

[87manche]

used to be they were all 12VDC, but now they pretty much all take 5VDC. I have an ancient hub that takes 12VDC, 2A, it's a four port, but it is USB 1.1.

These people have one for $50.
http://industrialcomponent.com/usbstuff/vighubkit.html

other than that it looks like MP3 car has a real nice unit, but it is 85 bucks like you said.

FWIW the MP3Car unit is made by Carnetix, you might be able to find it cheaper. They make really nice stuff that's bulletproof, but it's always pricey.
http://www.carnetix.com/

 

[casm]

used to be they were all 12VDC, but now they pretty much all take 5VDC. I have an ancient hub that takes 12VDC, 2A, it's a four port, but it is USB 1.1.

Yep. USB1.1 would be painful for the amount of data I could conceivably have to move across it - as an example, loading a full North American map set to my GPS takes about 2 hours. Not that I do that particularly regularly, but getting as much speed out of it where I can is a definite plus.

These people have one for $50.
http://industrialcomponent.com/usbstuff/vighubkit.html

Except that that one just does the voltage conversion in the lighter adapter before squirting it down the line to the USB hub. Really want to keep to an all-in-one design if possible.

Apparently some hubs that have more than four ports have been known to run on 12V, so I've been looking (unsuccessfully so far) at what might be out there currently in that department.

 

[87manche]

the industiral component one says it's a USB compliant hub with 480Mbps data transfer rate. It also comes with a host cable, so I'm pretty sure it does data, not just DC charging.

Package Contents:
USB 2.0 4Port Hub and host USB cable
Universal 100/240 VAC 50/60 Power Adaptor with UK/EU adapter (North America or Europe or Asia)
Universal PDA/HandHeld USB Car Cigarette Charger/Adapter Features and USB Power Cable

edit: nevermind I see what you're saying.

Why not take apart it's 12-5V converter and hardwire it into the chassis. Or for that matter you could do a 12-5V DC-DC power supply and wir that into the chassis and use whatever hub you wanted.

 

[casm]

Why not take apart it's 12-5V converter and hardwire it into the chassis. Or for that matter you could do a 12-5V DC-DC power supply and wir that into the chassis and use whatever hub you wanted.

True, either one would work. I'm mainly just hoping to find a one-box solution to it, but it's increasingly looking like the options in that regard are either build it or pay substantially for it. Somehow I suspect I'll end up with the former.

 

[87manche]

I've decided that I'm going to take a cheap inverter with USB power and decase it, mount it in the dead space in the dash and wire it to a faceplate that's unused below my radio, so I know what you're talking about. Seems they never make exactly what I want, so out comes the iron.

 

[casm]

I've decided that I'm going to take a cheap inverter with USB power and decase it, mount it in the dead space in the dash and wire it to a faceplate that's unused below my radio, so I know what you're talking about.

Heh, funny you should mention that - the inverter and 110V power outlets are also on the cards.

Seems they never make exactly what I want, so out comes the iron.

Exactly. And this seems like the sort of thing where it should be a case of Google it, give the nice website $20, and wait for UPS to turn up. Judging from the posts that I'm seeing on other forums there's evidently a market for this kind of device; it's just that nobody makes it.

</rant>

 

[kastein]

The extra current will only go to the loads that require it, the others will be fine. Your only worry is smoking the hub from overcurrent.

I would get or build a simple 12V to 5V regulator and install it inside the hub's case. If you want linear (good up to 1 amp, or 1.5 amps if you heatsink it appropriately) all you have to do is stuff an LM7805 based regulator circuit in there, otherwise, look into the National Semiconductors Simple Switcher series of parts. Can get 80+ percent efficiency in regulation for a few bucks in parts, I used the LM2575 last time I did one of these. It needs 2 or 3 electrolytics, a Schottky rectifier good for a few amps, and a smallish inductor as support components.

You can also open the hub up and see if you can find a regulator on the board. If the power jack feeds directly into a regulator anyways, just look up what it's max input voltage is, if it's at least 15 to 18 volts, I'd just dump 12 volts on it without thinking about it further. Make sure it feeds the USB ports off the regulator output instead of directly off the input jack first.

 

[87manche]

The extra current will only go to the loads that require it, the others will be fine. Your only worry is smoking the hub from overcurrent.

I would get or build a simple 12V to 5V regulator and install it inside the hub's case. If you want linear (good up to 1 amp, or 1.5 amps if you heatsink it appropriately) all you have to do is stuff an LM7805 based regulator circuit in there, otherwise, look into the National Semiconductors Simple Switcher series of parts. Can get 80+ percent efficiency in regulation for a few bucks in parts, I used the LM2575 last time I did one of these. It needs 2 or 3 electrolytics, a Schottky rectifier good for a few amps, and a smallish inductor as support components.

You can also open the hub up and see if you can find a regulator on the board. If the power jack feeds directly into a regulator anyways, just look up what it's max input voltage is, if it's at least 15 to 18 volts, I'd just dump 12 volts on it without thinking about it further. Make sure it feeds the USB ports off the regulator output instead of directly off the input jack first.

those are all possibilities, I would definitely go switched instead of straight 7805, 7805s start generating lots of heat when you load them up.

 

[kastein]

Definitely agree with you on that. If you think about it, at 15 volts in with the alternator cranked all the way up, the regulator is only 33% efficient maximum (15 volts in, 5 volts out, essentially the same current in and out), the rest is getting pushed out the heatsink tab.

 

[casm]

The extra current will only go to the loads that require it, the others will be fine. Your only worry is smoking the hub from overcurrent.

Hm, OK. I seem to recall issues with powered USB hubs in the past where they just pulled whatever current level was coming into it, then just did a straight passthrough of that current to each port. That's a years-old memory, however, so may not apply to the current generation of hubs; I'll definitely look into it some more.

You can also open the hub up and see if you can find a regulator on the board. If the power jack feeds directly into a regulator anyways, just look up what it's max input voltage is, if it's at least 15 to 18 volts, I'd just dump 12 volts on it without thinking about it further. Make sure it feeds the USB ports off the regulator output instead of directly off the input jack first.

You know, that's a good idea; I hadn't even considered that.

Looking at the $15 Amazon USB hub again, the description lists the external power supply AC input at 100 - 240V, then immediately describes output at +5V / +12V, 1A. This makes me suspect that the unit is capable of 12VDC input - and at $20 to my door, I'm thinking I'll pull the trigger on it and see what happens.