Battery issue

[Al G]

I've had a 57 Tbird for about 2 years and never a battery problem. This morning I went to start it and battery is dead. Put a meter on it and read about 8 volts. Now here's the strange part. I went to connect a battery charger, holding the negative cable in one hand not touching anything, connected the positive cable with the other hand and it sparked when making contact with the positive terminal. The charger was not plugged in. What would cause it to spark like that?

[rspears]

Al, if the battery charger was not plugged in it seems to me that you just had a potential difference, +8V in the battery positive to 0V in at the charger, so you got a spark from the battery terminal to the lower potential charger cable - not really to "ground" but to the zero potential at the charger so there was electron flow.

[firebird77clone]

Your charger has a significant amount of capacitance. The spark was the battery charging the capacitor

[Al G]

Take off the battery negative cable.
Then, try the battery charger again. Does it still spark when touching the pos cable of the charger to the battery ?

ps:
https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

It didn't spark with the negative battery cable disconnected. Then again it didn't spark later with both cables connected. Sounds like the capacitor charging is what was happening (it's an old charger). I never experienced that before and it surprised me.

I need to get a better meter to search for the draw. Thanks for the link.

[jerry clayton]

Was the charger a smaller unit and setting on the car???????

[firebird77clone]

The diagram shows an electrolytic capacitor in parallel with the output. It would charge instantaneously upon connection.

[firebird77clone]

It could have been a dome lamp left on maybe?

[Al G]

Was the charger a smaller unit and setting on the car???????

It was sitting on the plastic tile floor.

[Al G]

I don't think anything was left on. Yes, it has a clock that only seems to work when the engine is running.

Last time I started it was about a week ago. It restarted today after about 3 hours on the battery charger. For the short time I installed a battery disconnect today. That will work until I can chase down the problem. I also left it connected to a battery tender.

[jerry clayton]

You should of had to deal with the batteries on the Hobart generators that were modified to start the Caravel jets back in early 60s------

[NTFDAY]

I agree with Denny, but I would take the battery back to where it was purchased and have it load tested. Anymore it's not uncommon to have a fairly new battery develop a weak or dead cell.

[jerry clayton]

Most aircraft were 24-28 volt-Caravell were 124 dc--------12 large heavy duty 12v wireed in doubles for charging from the Hobart then big knife switch that swapped them to series for the 12x12-------------

[jerry clayton]

possible drains???????? Points closed causing condensor charge( would of caused a spark on disconnect), sticky brake pedal, starter solenoid, and/or bendix--------radio, gererator/ voltage regulator, glove compartment light,dash lights, turn signal flasher--------

[Driver50x]

How long did the car sit since you last drove it? If you have a digital multi meter, hook it up in series with the battery cable to measure the amperage draw with everything turned off. It should not be over 25 milliamps.

[rspears]

How long did the car sit since you last drove it? If you have a digital multi meter, hook it up in series with the battery cable to measure the amperage draw with everything turned off. It should not be over 25 milliamps.

..... and if it IS over 25MA you can pull fuses one at a time, watching the meter to see when it drops, to find which circuit is feeding the draw/drain while it's sitting idle, and then go through that one circuit to find the culprit. A simple process of elimination.