Didn't have a chance to do anything with it yet, but I'll be working on it tomorrow.

 

Ok, the circuit seems to be functioning, but it is limiting it to around 20 amps. What kind of modifications can I make to limit this to say 8 amps?

 

What value series resistor?
How long is the pulse transient?
Does it spark appreciably?
Probably the only way to control the peak current now is to throw in some series inductance to reduce its rate of change so that the circuitry can respond while it is charging.
A faster op amp will help--get rid of the noise filter cap C2 too

 

The series resistor is 4.7. I am going to check the sparking now I didn't see any but I'm going to do more tests to see if I can get it to arc at all. 20 Amps might be fine. I will get back to you after I finish the tests. I believe what I can measure for the pulse transient, it is arond 10-20us.

 

Alright, its still slightly sparking. I'm going to see what I can do to limit it lower. I think I might need a faster op amp.

 

Just did a DigiKey search for a faster op amp.
This is what came up--looks like a really good device--cheap--20x faster
Supply voltage up to 36V
Common mode input range includes 0V
http://search.digikey.com/us/en/products/MC33272APG/MC33272APGOS-ND/920883

Spike current should drop to about half--pulse width less than 5us--should get rid of your spark

p.s. make sure that you remove the 100pf noise filter as that will slow it down

 

Well the issue doesnt seem to be an electrical fix at all... It seems that the barrel on the device itself is made of some different type of material that when the barrel makes contact, it reacts and sparks. No matter what circuit we use it sparks everytime, whether or not the inrush is limited. If we connect a dc jack on the outside and then connect our circuit or power supply to this jack instead, it works without issue...

 

Is there a ground current or something?

 

Not really sure. I think at this point we are just going to forget about it. Its not really worth the effort. A new DC jack solves some of the issue by hiding the spark more inside. Not really the solution but it will have to do for now.

Thanks alot for your help it was really awesome and I learned alot.