Negative battery terminal sparks while starting

[jpian0923]

My negative battery terminal sparks while starting.
I posted a video on my YouTube channel.
Jpian0923 on YouTube.
Any clues as to why this is happening?

[romantic comedy]

I dont see the video, but many others.

First guess is a loose connection.

[ndutton]

Jim,

Please don't be discouraged by this thread's lack of activity. The first response hit the nail on the head. You have electricity arcing across a gap.

[Kelly]

loose connection at negative post

Definitely spooky. I agree with Romantic Comedy, could this be "anything but" a loose connection? Perhaps the terminal in the battery itself is beyond its useful life span?

Be careful with this...sparks and gas (and cardboard Budweiser box) don't mix!

[Dave Neptune]

Check it

j, time for some battery and cable maintenance. Did not look up the vid but sparks are like Neil said there's a gap or somethings loose! I did new grounds on my boat last season and it made a big differance. This year I am doing the main positive feeds from the batteries and new power leads to the panels and a rewire of the engine and ignition.
First is the terminal loose in the battery, if so its done!!! Check the connection closely and the cable to the lug connection too.
Good rule in a boat is no exposed sparks.

Dave Neptune

[edwardc]

I looked at the video, and It's hard to see the exact configuration of your negative terminal, but it looks like you have more than one wire lug on it.

If so, it is important that the heavy, high-current cable be the bottom-most one. Otherwise, you will be pulling a portion of the high starter current through the contact faces of the other lugs. Any corrosion or poor contact there will cause heating and expansion and contraction, which will loosen the connection and cause the condition to worsen.

In the video, the flash of light does not seem to have the strobe-like abrupt on-off-on-off of an arc, but rather the slightly more gradual "ramp-up" "ramp-down" of something being heated to incandescence, although this may just be an artifact of the video.

Whatever it is, you need to get it fixed before you have a fire on your hands!

[jpian0923]

It is loose.
It has a wing nut that I hand tightened. (not tight enough)
I need to change that out and clean it up a bit.
I chased an "imaginary" short for an hour or so.
Thanks guys.

There are other wires attached to it.
I need to organize them better.

[ndutton]

It's my opinion that only battery cables should be attached to the battery, not the variety of branch circuits we see all the time. Even battery charger leads can be relocated to the battery switch and still serve the same function.

I see no good reason there should ever be a need for more than two cables attached to any battery post.

[lat 64]

It's my opinion that only battery cables should be attached to the battery, not the variety of branch circuits we see all the time. Even battery charger leads can be relocated to the battery switch and still serve the same function.

I see no good reason there should ever be a need for more than two cables attached to any battery post.

I would agree with that.

I cannot say my boat is so though. This is a sobering thought; my two batteries are right next to the engine. #1 is right next to the carburator, fuel pump and lines. There must be six or seven wires crammed onto the terminals. It's always been a rats nest to undo every time I want to work with it. I would love to move the batteries out of the engine "room" and under the quarter berth where the old gas tank was. You all would be very envious of the room I would gain around the engine if I did that.
should I tell my wife I need to move them, and we need to buy a new panel?
Please say "yes"!

This old photo show pretty much how it still is. I have moved the coolant tank out of the way already though.
Russ

[edwardc]

It's my opinion that only battery cables should be attached to the battery, not the variety of branch circuits we see all the time. Even battery charger leads can be relocated to the battery switch and still serve the same function.

I see no good reason there should ever be a need for more than two cables attached to any battery post.

I agree also. When I rewired my power feeds, I did this, moving all the various branch circuits to a separate terminal block. It cleaned up things tremendously!

I did, however, discover two exceptions:

1) The voltage sensor leads for a battery monitor system, such as the Xantrex Link-Pro.

2) The voltage sensing leads for a "smart charger" system.

Both of these have to be attached directly to the battery terminals in order to correctly sense the exact battery voltage, and not include any voltage drop across the wire from the battery to another point. Since these circuits are both looking for changes in the range of tens of millivolts, the correct connection point is important for their proper operation.

I've also got temperature sensors for both the battery monitor and the smart charger that, while not electrical connections, mount directly on the battery post to properly sense its temperature.

[ndutton]

In my defense Ed, my charging systems aren't smart. They're as dumb as a sack of hammers. Accordingly I don't have all the fancy sensors to deal with.

[roadnsky]

This thread needs some pics!

[hanleyclifford]

This business of voltage sensing and monitoring had me running around in circles until I settled in on the understanding that voltage in a dynamic system is variable throughout the system. Obviously voltage will be highest at the alternator output terminal. But even at cruise rpm the voltage at the battery positive terminal could be significantly lower. With an adjustable voltage regulator you need to set voltage such that batteries are maintained at the voltage desired while also satisfying other electrical considerations such as coil positive and sensitive electronics. For this reason it is advisable to monitor voltage at several points while at cruise rpm. Of course coils are among the most sensitive item of all requiring a resistor in most cases but I have also gained an enormous improvement in performance from a depth sounder by placing a 1 ohm resistor in front of it.

[jpian0923]

You guys nailed it. This is probably the result of the arcing. Time for new stuff.

[sastanley]

Jim....100% for sure, that fitting is toast. What was that connected to?

Nice work!