Dramatic battery discharge

tbm3fan

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Not in my Polara but the Mercury. I was working on cleaning up the power window motor on the passenger side. I wanted to see it in action with the panels off to see why slow. So I connected the battery and nothing from it's switch. I then tried the main switch and got nothing. I then decided to start the car and see. So I primed the car with gas down the carb, it had been awhile, and it started and then puttered out. Poured a bit more gas and the car started with a roar into fast idle and a loud rattling from the engine compartment. Went to shut off the engine and it didn't turn off with the keys in my hand. I had to run around and pull off the + cable which stopped the engine. Looked it over wondering where the noise came from and will it do it again or act like the first time. The moment the + cable just touched the battery cable there was dramatic sparking while in my hand and I pulled away. Did it on both terminals when trying to connect. Something got open or a short all of a sudden?

Battery_sparking.jpg
 
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Big_John

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With a big spark, something is drawing pretty heavy. Since the car won't shut off with the ignition key, I'd be suspect of the ignition switch. Since the battery might be discharged, I'd be cautious of creating any more big spark as you can ignite the hydrogen gas coming out of the discharged battery. Battery explosions are no fun...

I think it's something more than this, but a fast check of the other circuits in the car can be done with a voltage drop test across the fuses. This video will explain it easier than I can. Starts around 1:20 or so.

 

tbm3fan

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I looked up parasitic draw but one that means connect the battery which is impossible. Usually those draws are in milliamps and not dozens of amps. Two, the draw was so big you should see the negative terminal as compared to the positive terminal. What happened in the 30 seconds between the two starts stumps me. The battery which was at 12.8 V two days ago is at 12.3 V after all this. I can look around but am too leery to connect the battery again.

PS: right now, just like after this episode where I stood and stared at it, I am thinking stuck starter solenoid and that rapping noise the starter still engaged.
 
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'66 Fury I

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If you connect one battery cable and then connect a test light between the other cable and the remaining battery terminal, the light will show any parasitic draw. You can then find the draw by disconnecting circuits one-by-one. For example, since you suspect trouble in the starter, disconect the cable to the starter. If the light goes out, you have found the problem. If not, continue disconnecting one circuit at a time until you do. Removing fuses is simple. A shorted alternator or chafed wire/ cable are sources that come to my mind.
This method limits the load on the battery to a maximum of the current the test light can draw, making this quite safe. Lindsay
 

tbm3fan

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A test light, huh? I have one so this is a great suggestion. I believe my trouble is inside this below

crown-automotive-starter-solenoid-J3235898.jpg
 

tbm3fan

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More research and I think I'll start with the relay on the starter which I have heard from others that the contacts can melt together causing all power to keep going to the starter and cause the rattle. That relay also sends 12V to the ignition coil to compensate for the voltage drop while the starter is running. That would be why I couldn't turn the car off. So with the test light used it's light should go out the moment I disconnect the starter cable from the starter solenoid.
 

1970FuryConv

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I agree with starter relay. It was first thing I thought when I saw this thread. No knowledge of Mercury vehicles, however.
 

Loadrunner

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A solenoid for those who couldn't a Ford anything better ;]

Something got open or a short all of a sudden?

Open circuits aren't a draw.

"Shorts", the perennial vehicular electrical condition, blow fuses.

You have a "draw", easy enough to trace.

A blown diode trio could be the cause.

1st day of school for electrical, instructor describes the "three stages" of an electrical circuit. Ok, open, shorted. That's it folks, no variables.

Somehow, shorts stick in people's minds. Short shorts. If I had a buck for everytime someone described an electrical problem as a short, I'd be richer than Elon now.

If someone has a headlight out, a short.

Taillight out, a short.

Fan won't blow, a short.

Wipers that don't wipe, sprayers that don't spray, shorts.

I see dumb people ;]
 

1970FuryConv

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A solenoid for those who couldn't a Ford anything better ;]



Open circuits aren't a draw.

"Shorts", the perennial vehicular electrical condition, blow fuses.

You have a "draw", easy enough to trace.

A blown diode trio could be the cause.

1st day of school for electrical, instructor describes the "three stages" of an electrical circuit. Ok, open, shorted. That's it folks, no variables.

Somehow, shorts stick in people's minds. Short shorts. If I had a buck for everytime someone described an electrical problem as a short, I'd be richer than Elon now.

If someone has a headlight out, a short.

Taillight out, a short.

Fan won't blow, a short.

Wipers that don't wipe, sprayers that don't spray, shorts.

I see dumb people ;]
Problem: @tbm3fan had to turn off the engine by pulling the positive battery cable because the Merc would not turn off with the keys. Big sparks if he tries to reattach the battery cables.

If your starter solenoid got shorted, wouldn't you have a draw from the starting system? That would make a big spark when you tried to reattach battery cables because the starter draws a lot of current.

Big John pointed out that a shorted ignition switch might continue to draw power.

Either way, we are talking about a draw because of a short. Semantics, I realize :lol:
 

Loadrunner

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Luck of the draw, picking the short straw, it's all in there ;]

And yes, if the Ford style solenoid was shorted, power would be going to the starter fields coils, not a pretty situation as Ford dispenses with a conventional starter mounted solenoid to propel the starter drive into the flywheel, but instead uses an unconventional swinging field coil pole shoe to shove the drive in the flywheel for starting only, the drive mistakenly called a Bendix by many for generations now. A Bendix is not electrical at all, has a helical thread on the armature shaft drive end, and spring ,and works on centrifugal force.
 

Loadrunner

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Short answer is if the starter solenoid is shorted across, the starter will engage - spin the engine - as soon as you connect the battery, unless the battery's weak or cables are corroded etc. If it doesn't than you can rule out the solenoid.

Going back far enough with FoMoCo products, positive ground with a mechanical regulator of course, which needed some voodoo spark thing to get the polarity right, which I had to do a bunch of times myself, getting the polarity of the regulator right, or correcting the polarity of a regulator that had become reversed.

Back in or about 1980 neighbor down the road had a 1960 Rambler with + Ground, and somebody working on the car - while he was gone out of state - didn't notice that, jumped it backwards or instaled a battery backwards, consequently the car had some electrical issues as you would expect which resulted in the battery exploding in said friend's face after he came back from his trip, him being a wheat farmer's kid was mostly unfazed by the experience but I like to learn from other people's mistakes.

Wear eye protection. Sometimes ;]

The sweet part of the FoMoCo solenoid arrangement is that any decent pair of pliers will bridge across the contacts if the ignition key/circuit has failed, so a simple lead to go from any 12V+ source to the hot side of the coil - Ford very inconveniently shrouding theirs is some bizarre Ford only coil wire attachment plug to threadless contacts - and a pair of pliers, and you've got the rig "hotwired, started and running".
 
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tbm3fan

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Test light results:

#1 Nothing disconnected at starter solenoid
#2 Starter cable disconnected at starter solenoid
#3 Starter and now ignition disconnect at starter solenoid


Test_light_draw.jpg
Test_light_starter_disconnected.jpg
Test_light_starter_ignition_disconnected.jpg
 

tbm3fan

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Swapped the solenoid out and all is good. Be interested in what the inside of the one removed looks like if I can get into it. I'm going to remember that test light suggestion as electricity is not my thing.
 

1970FuryConv

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Swapped the solenoid out and all is good. Be interested in what the inside of the one removed looks like if I can get into it. I'm going to remember that test light suggestion as electricity is not my thing.
Awesome!
 

'66 Fury I

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Glad you solved your problem. Those Ford solenoids (starter relays?) are useful in other situations. I used one to install a 12v boost system on a '50 Cadillac with a 6v system and a weak starter. Second starter button under the dash and it started instantly!
It would be interesting to see pics of the old units innards. Lindsay
 

Loadrunner

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Something to know about solenoids - and they are all the same on the inside, a large copper washer making contact across two poles at a rather high amperage - is that an old dying or otherwise defective battery will destroy them.

I worked in a starter shop for two years, rebuilding Delco 50MT starters that replaced the "Pony motors" on big CAT tractors as well as other HD truck applications. 6 at a time on a turret you bolt the nosecones into, these are 80lb starters and there's nothing like hoisting one into place laying on your back under a Kenworth out in the dirt somewhere.

What I learned from my boss Paul, who'd been running this shop since out of high school, is that a crap battery will melt the solenoid contacts by way of very high amperage across the contacts.

At normal voltages - a battery should never drop below 9.6V on a load test, if it does and is properly charged it is junk - the amperage is not excessive, but because of the inverse relationship between volts/amps, if the battery voltage drops excessively while cranking the amperage will go sky high and melt the contacts, sometimes to the point of having a runaway starter, which is a pretty terrifying situation, with engine running. Shutting it off doesn't stop it, the only cure is disconecting the battery as quickly as possible.

So the best prevention for your starter solenoid is a healthy fresh battery from a top maker, don't buy cheap batteries, they are not worth it. I use Deka batteries only now, much preferably with a sealed top to prevent holddown corrosion, easily 8 years, sometimes 10 years life.
 
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1970FuryConv

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Something to know about solenoids - and they are all the same on the inside, a large copper washer making contact across two poles at a rather high amperage - is that an old dying or otherwise defective battery will destroy them.

I worked in a starter shop for two years, rebuilding Delco 50MT starters that replaced the "Pony motors" on big CAT tractors as well as other HD truck applications. 6 at a time on a turret you bolt the nosecones into, these are 80lb starters and there's nothing like hoisting one into place laying on your back under a Kenworth out in the dirt somewhere.

What I learned from my boss Paul, who'd been running this shop since out of high school, is that a crap battery will melt the solenoid contacts by way of very high amperage across the contacts.

At normal voltages - a battery should never drop below 9.6V on a load test, if it does and is properly charged it is junk - the amperage is not excessive, but because of the inverse relationship between volts/amps, if the battery voltage drops excessively while cranking the amperage will go sky high and melt the contacts, sometimes to the point of having a runaway starter, which is a pretty terrifying situation, with engine running. Shutting it off doesn't stop it, the only cure is disconecting the battery as quickly as possible.

So the best prevention for your starter solenoid is a healthy fresh battery from a top maker, don't buy cheap batteries, they are not worth it. I use Deka batteries only now, much preferably with a sealed top to prevent holddown corrosion, easily 8 years, sometimes 10 years life.
Thanks for the info.
What makes Deka better? Unfamiliar with the brand.
 
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