USB 5v power from Model A 6v geni/battery

freddo

freddo

Junior Member
Just a thought,

with the increasing availability of 5v USB powered mobile devices such as GPS, phone, MP3 players etc etc, has anyone thought of putting together a USB powered system drawing from the Model A 6v system.

Seems more logical than upscalling 6v to 12v with the inherent losses to feed the same low current devices at 12v.

I'll do some web searching, perhaps a Model A'er has already produced such a circuit.

Any ideas ?
 
you don't need to do anything special here. just setup a cigar lighter power outlet with the positive (ground on a stock model A) in the center post position and the negative on the shell. The cigarette lighter adapter for your phone or GPS will reduce the 6 volts to 5 for the device.
 
More than one guy has reported direct connect to the 6V works for them.

I personally would want the voltage to be better regulated and protected against over voltage. Seems to me there would be a market for a 5 volt regulated USB power port for the A that works off of the 6 volts.

I would also think a small 6 to 12 converter and then any of these off the shelf 12v to USB adapters would be a good safe solution too.
 
We reviewed just such an item in the Model A Times Vol 6 Issue 4. Comes from Auto Physics. Well actually I thought you were asking for 5amps not volts, this unit takes 6volt and makes it 12 volt at 5 amps enough to run all the items you asked about.
 
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Freddo,
If you do decide to hook up a cigar lighter plug to power your GPS, etc, it should work well for most brands. A major CAUTION. If you allow the small USB plug that powers your GPS to touch against any of the metal parts of your "A" that are grounded, it will fry the USB to 12V power cable instantly. I keep a small rubber cap to cover the USB end when it is unplugged from the GPS. I fried one before I started doing this!
Tom
 
Kevin in NJ said:
More than one guy has reported direct connect to the 6V works for them.

I personally would want the voltage to be better regulated and protected against over voltage. Seems to me there would be a market for a 5 volt regulated USB power port for the A that works off of the 6 volts.

I would also think a small 6 to 12 converter and then any of these off the shelf 12v to USB adapters would be a good safe solution too.
Click to expand...

No, you misunderstood my directions.

You hook up a cigarette lighter socket on your 6 volt car. MAKE SURE YOU ISOLATE THE SOCKET FROM THE CAR AND GET THE POSITIVE AND THE NEGATIVE RIGHT WAY AROUND! Then you plug your car charger for your cell phone or your GPS into that socket. There is a voltage regulator chip in the car charger that is designed to take 12 volts DC down to the 5 volts that the phone or GPS device is expecting. It is happy to convert 6 volts down to 5, instead of 12 volts down to 5.
 
If need be and according to Jim its not, It would be fairly easy to build a linear regulator to drop 6-8 volts down to 5 using something like a 7805.

The design would depend on how much power the device needs. If I recall USB maxes out at I think 500ma? Should be fairly easy to achieve with a 7805.
 
You can purchase an inverter from Bratton's that will convert positive ground 6-volt power to 12-volt negative ground power. The device uses a common ground so there is no concern about isolating devices being powered. The inverter is small and can be mounted out of sight.

The part number is 14940, on page 65 of the Bratton catalog, rated at 2.5 amps. Sells for $100.

I bought one several years ago and mounted it on a bracket that tucks under the dash rail of my Vic and added an off\on switch, indicator light, and a cigarette lighter type power outlet. I use it to recharge my cell phone and power my Garmen.

You can read about it in a technical article. Go to www.ocmafc.org, click on tech articles in the left hand menu, click on my name at the top of the new page and scroll down to "power inverter".

If you click on the above web site you will get a window that says the domain has expired. I don't know what that is all about, the web site is still there. Do a google search for "Orange County Model A Ford Club".

Tom Endy
 

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Tom-
The unit from Bratton's is really good for putting a 12 volt accessory, like a radio or CB, in your 6 volt car. The GPS and cell phone only need 5 volts (if it uses a USB-type plug) which the car charger can give you from your 6 volt car.
 
Here is a schematic, heat sink the regulator and it will give almost 1 amp (1000 mA).
 

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Mike I would probably increase the capacitors in that schematic if using for 1A. 1000uf would work well for both caps before and after the regulator in my opinion. The 100nf should stay.
 
Tom Endy said:
You can read about it in a technical article. Go to www.ocmafc.org, click on tech articles in the left hand menu, click on my name at the top of the new page and scroll down to "power inverter".

If you click on the above web site you will get a window that says the domain has expired. I don't know what that is all about, the web site is still there. Do a google search for "Orange County Model A Ford Club".

Tom Endy
Click to expand...

Its a .com not .org www.ocmafc.comhttp://www.fordbarn.com/forum/www.ocmafc.com
 
Clydes 31 P/U said:
Jim/TX, Did you put a fuse in line with your cigarette lighter plug? I am thinking about putting a 3 amp in the + feed line.
Click to expand...

YES!!!

3 amp is good. I think that's what I used. The GPS or cell phone will draw much less than that (under an amp).

But on a positive ground car, I would put it in the negative lead...

Jim
 
Mike V. Florida said:
Here is a schematic, heat sink the regulator and it will give almost 1 amp (1000 mA).
Click to expand...

This is basically what they have in the plug part of the car charger for your phone or GPS. They do not attempt to put out 1000 mA because they know their devices do not draw that much. I have never measured the draw but would be amazed if over 100 or 200 mA.

Jim
 
Per the USB 2.0 spec, the max current available is 500 mA per device. However, many devices like disc drives, draw more than 500 mA. These devices count on the fact that for say 4 USB outlets, the total from the computer is 2.0 A, and they assume that they can take the total allowed themselves.

The spec. only allows, though, 500 mA.

For the USB 3.0 spec., I lobbyed for more current and got the max to 800 mA per device.

Marc
 
marc hildebrant said:
Per the USB 2.0 spec, the max current available is 500 mA per device. However, many devices like disc drives, draw more than 500 mA. These devices count on the fact that for say 4 USB outlets, the total from the computer is 2.0 A, and they assume that they can take the total allowed themselves.

The spec. only allows, though, 500 mA.

For the USB 3.0 spec., I lobbyed for more current and got the max to 800 mA per device.

Marc
Click to expand...

Marc,
Arn't devices supposed to request current before it is delivered? From a PC that is.

A few years back I blew out a motherboard from plugging in too many devices and was surprised as I thought it wasn't supposed to be possible.
 
MrTube,

Yes, you are correct. The USB device should start up with a small amount of current, and then negotiate for more...up to 500 MA.

In most applications, that does not happen and the Host just supplies 500 MA or the total that all USB ports could supply...i.e. 2A with 4 ports.

I have a USB CD player that has two USB connections. One communicates to the Host and the other just pulls 500 MA with no communications. In that way, the external CD palyer can get 1A, but Technically, should only get a little over 500 MA.

The USB idea was a great step forward for Computer users, but the implementation is not often "to the spec."

Marc
 
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