I have a 73 and I have been having some dead battery problems. I find that I have a 7 volt draw from the battery when the car is turned off. What are some things that could cause a 7 volt draw. Isn't a 7 volt draw something unusual, compared to a full 12.

 

How/where are you taking this measurement?
In order to track down a battery draw you're gonna want to measure amps vs volts. There are numerous threads (many recent) on how to accomplish this.

 

With a handle like Jigowatt, you would think you would know somethin about lectricity. There is no such thing as a 7 volt draw. We don't know what you are talking about.

 

nm.

 

Do you mean that when you put a voltmeter on the battery, it shows ~5 (or 7) volts (5 + 7 = 12) with no load applied (i.e., nothing turned on)?

If so, disconnect the battery, put a charger on it for a while, and try a reading at the battery terminals. If this is still the case, you've got some bad cells in that battery and it needs replacement.

 

Brand spanking new battery, I use the voltmeter to test to see if there is anything pulling juice. So I plug one probe to the negative terminal then continue the circuit to where it would have gone.. and pull all the fuses. Normally I will see nothing, but for some reason I see 7. Like 7 volts are available in the circuit... I understand that volts are not the preferred way to check for parasitic draw. And I understand that amps are what you measure currant in, but I do not have a amp meter, I have a test light and battery. The battery will read 12 volts if I test it directly. Basically anything under 12 should be a draw... right?

Oh and I am not an electrical expert.. my handle is a reference to Back to the Future (1.21 JIGOWATTS!... NOT a gigawatt as in a billion watts.

 

Try pulling the wires off the alternator and see what you get then.

 

The only circuit I know of that supplies about 7 volts to a component of the engine is the resistor wire to the coil of a point driven engine. I'm not an expert but when the engine is running, about 7 volts is supplied to the coil through a resistor wire to prevent burning of the points. Is it possible for that circuit not to open when the ignition is switched to the off position? If the points stopped in the closed position, then I would assume there would be a drain on the battery.

John

 

If you are trying to use a multi-meter to detect a battery drain when the key is not in the ignition, the following procedure is used

1. You need a multi-meter with a 10 amp [current] scale. {not a voltage scale} Most inexpensive meters have separate lead sockets for the 10 amp current scale. The other meter scale settings are milliamp ranges and are not capable of detecting an auto battery drain; if you use one of those scales and have a battery drain, you will blow the fuse in the meter or fry it.

2. Remove the positive cable from the battery. Use duct tape to hold the door jamb switches IN so the interior lights will not be ON (and cause a battery drain).

3. Connect the + meter lead to the battery + terminal and the - meter lead to the + battery cable. (put meter in "series" with the battery circuit)

4. Measure the battery drain on the meter scale. If the drain is more than .2 amp (just a little above the "0" reading on the 10 amp scale), there is significant drain when there should be very little drain with all circuits OFF. [Note: Some digital radios have a clock reading that is ON all the time. This usually draws less than .1 amp and is not a significant issue.]

5. Assuming you measure a significant drain, pull one fuse at a time from the fuse block to see if the reading changes. If it does NOT change, reinstall that fuse and mark it so you know it has already been tested.

6. When you pull a fuse and the drain disappears, that fuse is on the circuit which has the drain. You will have to research all the wiring and components that are connected through that fuse and further diagnose which specific item/wire is the source of the drain. A drain can be caused by a defective component or a worn through power wire that is contacting ground.

7. If you pull all the fuses and you still have the same current drain, there is a minor 'contact' short in the main power line (+ 12volt) between the battery and the fuse block. Check for insulation wear-through on the main battery cable and the following feeder wire(s) to the fuse block.

8. If you still can't find the drain, call a qualified electrician to search it out.

 

Fixed! Put a new alternator on today, no more drain. Thx alot for the help