Battery always dead

[Tony Ripepi]

Hi John,

All good suggestions here, we have all had our share of electrical gremlins.

What kind of Cobra do you have.....I had a problem with my Shelby and it was really tough to find. Ended up being the red light on the dash board above the ignition switch which ends up being a resistor in the charging circuit for the alternator, when the red light comes on before you hit the starter that current flows to the alternator and provides the exciter circuit.

The light is spring loaded and there was a washer around the mounting that gave it an intermitant open, the car would start and run on the battery until it was dead sometimes. If you put a jumper on it it would start and the battery would charge ---- Sometimes. As I said it was a devil to find, removed the washer and all was well.

Tony R.

[Xavier]

Yeah, I had the same issue. I wired the Alternator wrong. Turns out the one-wire alternator needed like 3 wires (can't remember) and I ran a seperate ground wire just to make me feel better. One of my employees fixed it under 30 minutes.

Live and learn.

[strictlypersonl]

The ERA is designed for the fan to run regardless of whether the ignition switch is on and the temperature in the bottom hose (where the thermo-switch is located) is above 175F. The fan will typically shut off after a couple of minutes if it is running when the car is shut off, which indicates that when the thermostat is open, there is some thermo-siphon action going on. That small flow (encouraged by the fan-cooled air in the radiator) keeps hot spots from forming in the block and heads. Therefore, post-shutdown boil-over is less likely.

Running the fan is also a small attempt to cool the engine compartment a bit after shutdown, which might help prevent fuel percolation during heat soak. Imperfect, but it might help a little. Running the fan for a couple of minutes is not a significant draw on the battery unless something else is wrong.

[Michael C Henry]

A simple test is to dissconnect the battery after charging and let it sit overnight and then reconnect to see if the battery held that charge, or has an internal short.
When I bought my car in Remo (August) It had a master switch mounted on the firewall accessoable from under the dash. It was a little awkward (impossible) to get to after belting in. I often negelected to turn off that master switch when running errands, either from forgetting or, expecting to be only a minute. After leaving the car the hot water would collect at the top of the engine and radiator (where the thermo sensors for the electric fans are) and turn on the fans (4). The fans didn't make so much noise that you could hear them from any distance. I'd return to the car after more time than I"d planned on and find the battery drained. If Iwas lucky enough to have enough battery to get the electric fuel pump to click a few times and any incline, I could get the car to roll and dump the clutch and start. Some times It didn't work. I tried a Battery Brain, a automatic battery disconnect switch that mounted to the battery and was supposed to dissconnect the battery automatically. I'd have it turned on to the manuall position or something and it didn't work. Then finally it quit working completely( I was actually sitting in the car in the street, engine turned off, talking to a COP and didn't notice the fans running. My fix was I mounted another master switch from Flaming River on the dash in series with that original master switch and within reach while belted in. Twist the red knob on and just bump it and it turns off.
I do not have MSD I have Mallory. There are two power wires one(switched) and another power on allways on (not switched) for the MEMORY. Different power draws. If your system is similar, make sure that the electrician didn't put them together to make it easy for himself.

[Blas]

An MSD box has a capacitor in it. Once that capacitor is charged, the box draws about the same amount of power as a radio does for the memory station presets....

[JohnM]

Hello All

It appears from all of the posts that this is a common situation that might involve the MSD

I do understand that the fan running after shutdown is mostly to cool off the engine bay and possibly prevent vapor lock etc. I some how feel better getting the heat out of the engine bay

My car is an Antique and Collectable brand. I want to look at the alternator again and its associated wiring.

Does anyone have the a wiring design for the alternator that can be e-mailed showing both the Ford wiring schematic and the GM "1 wire" style?

thanks

John

[strictlypersonl]

There's a section on the Ford alternator here.