Negative battery terminal spark

[44boggers]

Hi guys, I am sure this question is going to seem very but here it goes.

So I am just starting to put the basic electrical back in my truck. Complete frame off resto, so all wires, terminals and battery are new. I only have a 3 wires hooked up right now.

I have the positive going to the starter

I have the ground going from the battery to the back of the cylinder head.

I have a ground strap going from the same ground on the cylinder head to the frame.

That is it, 1 positive and 2 grounds.

So normally you would connect the positive terminal first and then the negative on the battery. But when I do this it the negative terminal sparks so aggressively it will melt the terminal.

But if I connect the negative first and then the positive there is absolutely no sparks.

Isnt this a sign of a short somewhere? but that seems impossible since there are only three wires hooked up to the chassis/block/battery and all new wires.

Only other thing to add, is the first time i tried this tonight had a battery tender still hooked up. So I thought maybe the battery tender was creating some sort of connection. So I took the tender off and still the same effect.

Would a freshly charged battery (hot off the tender) do something like this?

Thanks

Paul

[twcoley]

I would do some checking in your main fuse box under the dash and also your ignition key, it sounds as there maybe a short or a high amperage draw somewhere.
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[franken]

Electricity doesn't know or care which you disconnect first. Something is drawing current when the terminals are connected. Chances are if current is high enough to melt something, you want to connect a test light between a battery terminal and the battery. That will light when current flows, but limit current so nothing will be cooked.

Is the junction block on the FW connected to power? disconnect it.
If the light goes out at this point, the trouble's in something the j-block feeds. If it stays on, reconnect.
Is the alternator connected to power? disconnect it.
If the light goes out at this point, the trouble's imay be in the alt. If it stays on, reconnect.

[Dead Parrot]

Generally a bad idea to make the go-live connection at the battery. Sparks + battery gas can = boom. Disconnect the negative at the head, connect the battery terminal then reconnect the to the motor.

Possible there is something about the negative battery terminal and your negative cable that react poorly together. If you still get sparks when you contact the head, something is live on the circuit.

A radio can pull a brief spike charging up the power supply filter caps. I always get a spark when I reconnect to the alternator bracket.

[mongocanfly]

Not really a answer but you also need a ground from the body to the chassis..
.also dead parrot is right..battery boom is bad..I had one blow up in my face in my 55 1st series truck when I was in high school trying to jump it off on day..

[44boggers]

Hi guys. Thank you for all of the replies. Right now there is no body on the frame. It is just the frame alone. No other electrical components are wired up or even there to come into play. Not even the alternator is wired up yet. Literally just the battery connected to the starter plus the ground wires. That is why I was saying I can't see where a short is possible.

But maybe there is an issue with the ground terminal. The type of terminal I have for the positive and negative are the kind where you slide the wire into the terminal and use s set screw to secure them. So I already have the terminals connected to the battery and then I slide the cable inside the terminal. I get the spark when I go to slide the negative cable in ,but only if the positive is already connected. No spark at all if I connect the negative first and then the positive.

I am reading 14.87 volts at the battery and starter. As I said before I have a constant charge on the battery from the battery tender

Thanks guys
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[44boggers]

So here is what I found. When I have the negative cable inserted into the terminal and I install the entire terminal/cable onto the lug there is no spark what so ever.

Just to clarify what was happening before was I had the terminals already installed on the battery lugs. Then I would slide the cable into the terminal. With the positive installed first I would get a spark when I tried to insert the negative cable. It makes me wonder if the coating on the negative terminal (that I touched with the cable because it's a tight fit to slide the cable in the terminal hole) creates some sort of short or something. I'm not an electrical guy so I only understand the basics really.

Long story short. If I have the negative cable already installed into the terminal there is not spark. Only if I touch the cable to the outer casing of the terminal.

Even though the problem is solved I would love to hear some
Explanations of why this happens.

Thanks
Paul
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