Can ammeter be used for power source?

[OL JENNY]

I am installing a power inverter to use for a GPS or Cell Phone, and in finding a source of 6volt power, I wondered if comming off the ammeter would work? I will switch the power with an indicater light when it is powered. This would save finding a route from the starter which was my original thought.

[sidhartha]

I don't see way you couldn't. I've got a late 31 Tudor and the instrument panel light is fed directly from the ammeter. The threaded leads on the ammeter are not very long though. If there is a better way to hook it up one of the guys here will let you know. I've found this forum to be a cornucopia of information.

[Mike V. Florida]

Yup, it's unswitched power available at all times.

[Jim Brierley]

Yes, everything except starter amperage should go through the ammeter, makes no difference where you attach things.

[OL JENNY]

Either post? I know the left works, will it register if I use the right?

[DFS]

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Without seeing the circuit diagram, in general, the two connections of an ammeter are in series with either the positive or negative conductor. For your device, whether DC to AC inverter or 6V to 12V converter, make only one connection on the terminal of the ammeter (if it fits) and other connection to chassis for ground. Check these two contacts with a voltmeter first so that your device gets the correct polarity. If you are on the "downstream" ammeter terminal, you will see your device load, however small, on the ammeter. AND put a fuse in series with the device. There are probably more elegant and correct means to tap off power source.

[H. L. Chauvin]

Humble Opinion:

It is written in the Restorer Volumes that for safety:

1. All "additional" electrical accessories should be connected to the terminal located on the Driver's Side of the junction box on the firewall.

2. For those vehicles that have them, the circuits for the interior dome light under the roof & the electric windshield wiper are connected to this same terminal on the Driver's Side of the junction box.

3. This terminal on the Driver's side of the junction box fire wall has a wire that runs to the (+) side of the Ammeter located on the Driver's side of the Ammeter; and the Instrument Panel Light is connected to this terminal on the Ammeter.

4. NOTE: (The only accessory that I found thus far where it is recommended by the Manufactirer to connect their accessory to the "Passenger's Side" of the junction box are the "Logo" LED Signal Lights.

5. As mentioned in reply No. 2 above, not only are the Ammeter threads short, but it appears that more wire behind the instrument panel may be a nuisance; & it may be a better idea to connect a GPS/phone charger to the very near Driver's Side of the junction box, if not only for safety, but for convenience.

Hope this helps -- others may have other helpful suggestions.

[newshirt]

Here's an alternative to the mess of extra wires on your Model A... Batteries these days are powerful and last a long time. For instance, one rechargable R/C battery will power a GPS for 12 hours. You can recharge it at night, or just bring another battery for multi-day tours. If you aren't driving your A every day, this can be a simple solution.

[OL JENNY]

The drivers side of the junction box it is. The load should be so slight that I understand there is no need to have it register. I really appreciate all the help in the posts.

[OL JENNY]

The battery sounds like a great idea, unfortunately I now have all the other equipment. I seem to learn late--but it is a learning process isn't it.

[Jim Huseby]

I hope this helps a little in addition to what's been said and it may already be obvious. Electrical components will work using either side of the ammeter as a current source, BUT in order for the ammeter the show the actual relationship of charge to discharge ('lets you know if the battery is being correctly replenished, over charged or depleted), the components must be connected to the output side of the ammeter. You can test this easily by putting a load on one, then the other ammeter terminals. The terminal that causes the ammeter to deflect to "discharge" is the output side. If your A is wired to factory standards, then as stated above, the terminals on the junction box on the firewall come directly from the ammeter and the terminal on the driver's side will be a better terminal than the ammeter itself from which to take tour current. You can test the junction block terminals the same way I said to check the ammeter terminals. Also, make sure your additional components' amperage requirements can be met by your generator and its output adjustment unless you're running an alternator. Also, although you're going to take your current from the junction block, you should check the tightness of the ammeter terminals. BTW, many aftermarket ammeters can cause serious trouble.

[josh1331]

Where does one get an RC battery? And what are these used for. . Model toys? Josh

[29ModelA]

Originally Posted by josh1331

Where does one get an RC battery? And what are these used for. . Model toys? Josh

Any hobby shop will have them, they battery should be under $20 based on the last one I bought. The chargers can be $$ though, but they do have cheap ones that charge overnight vs 15 minutes or so.

Amazon, Ebay as well would have them.

[AL in NY]

You may want to check out your cell phone and GPS power supplies. Most hand-held devices run on 5 volts and their power supplies can take a variety of input voltages and still maintain the required 5 volts output. You may find out that they'll work on 6 volts if you use the correct polarity. I have a TomTom and the 12 Volt car power supply(charger) works directly off the 6 volt battery just by reversing the polarity.

[Bruce Adams]

I use a small "JUMP BOX" either under the front seat or in the rumble to power CB radio, GPS, and any other 12 volt item I might need on the road.
It certainly contains enough capacity to power those sorts of items and can be recharged at night in the hotel if on the road.