Possible solution to battery connect spark??

[NitroVal]

I was doing some thinking today working on my boat and remembered that DC current travels opposite of what most people think. It flows from negative to positive. I noticed that when I hook up the negative first, and the positive second, I get the spark, but if I hook it up vice versa, no spark (well visible and audible spark anyways). I may be wrong, but this theory is due to the fact that when you hook up positive second, the current meets a resistance with a residual load flowing against it. When you hook up negative second, the flow is already traveling in correct direction.
Are there any Bill Nye's out there or maybe someone with an oscilloscope or similar tools that can verify??

[domwilson]

You are correct, In DC circuits, the flow is from negative to positive. When you tried this, was it at two different times or back to back. The spark occurs because of the charging of the capacitors in the circuit.

[NitroVal]

I got the first spark (and a freakin huge one) when I hooked up the first ESC, then I tried it again on the same ESC with no spark. Then I tried it positive first on the second ESC and no spark... I'll verify it again, but I see what your saying. Maybe I just thought I was smarter than everyone else there for a second..

[Fluid]

The OP's theory doesn't hold water. I get a charge out of reading the demands for "no spark" when connecting the power wires to the ESC. Why is everyone so afraid of a little noise and light? It is the sparking of this connection that signifies the caps are functioning as intended to protect the ESC. Without the caps functioning the ESC will soon fail. If your ESC doesn't spark, you know to replace the caps. It is a method to prevent ESC failure. With care during the connecting process the spark won't damage your connectors, but even if they are damaged, connectors are a lot easier and cheaper to replace than a damaged ESC....



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[domwilson]

Capacitors take time to charge and discharge. That time can be changed by the load of the circuit. Here's a nice little tutorial to help ya out.. http://www.wisc-online.com/objects/i...objID=DCE10604

[domwilson]

So as you can see, if you did the check back to back, there may have been enough charge in the cap to prevent a significant amount of current flow. Thus reduced or no spark.

[Akoni]

So is there a "best method" to getting hooked up?

[Ub Hauled]

So as you can see, if you did the check back to back, there may have been enough charge in the cap to prevent a significant amount of current flow. Thus reduced or no spark.

So Dom, what da hell does that mean in English?!

[domwilson]

So Dom, what da hell does that mean in English?!

It takes time for the cap to discharge.

[Drag Boat Bob]

The OP's theory doesn't hold water. I get a charge out of reading the demands for "no spark" when connecting the power wires to the ESC. Why is everyone so afraid of a little noise and light? It is the sparking of this connection that signifies the caps are functioning as intended to protect the ESC. Without the caps functioning the ESC will soon fail. If your ESC doesn't spark, you know to replace the caps. It is a method to prevent ESC failure. With care during the connecting process the spark won't damage your connectors, but even if they are damaged, connectors are a lot easier and cheaper to replace than a damaged ESC....



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I agree with Fluid (did I really say that???)...

Even when there are no capacitors in a circuit, 'charging current' occurs. The amount is dependant on the attributes/size of the material.

I have closed and opened disconnects of 500kV (yep that is ½ a million volts; not under load obviously). There is absolutely no time when a spark does not exist. The only real question is 'how much'?

I have built many crossovers for speakers (with large capacitors), but still do not believe that the charging spark causes any damage.

I'm sure the pundits will come out now...

[NativePaul]

yes, touch the ends of the connectors first before sliding the bodies together, that way the spark erodes the ends and not the outer surface that passes current in normal use when they are fully mated.

[Drag Boat Bob]

One more thing...

There is a big difference between a no-load voltage spark and the amount of current necessary to burn something. Charging current is minimal.

[domwilson]

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capchg.html

[Ub Hauled]

one of the reasons I am installing resistors in my HV systems is that I don't like to keep re-soldering the plugs every time one gets in such bad shape because it was eaten by the sparks...
I don't see anything wrong with that... as far as the caps go, I am not 100% sure if sparks damage it every time, but you know what, I don't wanna find out the hard way.

[domwilson]

one of the reasons I am installing resistors in my HV systems is that I don't like to keep re-soldering the plugs every time one gets in such bad shape because it was eaten by the sparks...
I don't see anything wrong with that... as far as the caps go, I am not 100% sure if sparks damage it every time, but you know what, I don't wanna find out the hard way.

Good response. Do what makes you happy and what you feel comfortable with.