Magnet coil help (turns, gauge, for coilgun)

Hey everyone I'm building an coil for a coilgun and need help figuring out best wire gauge and # of turns for my coil.

I will be using 3, 13.6v lithium car batteries in series so about 40v, and these batteries can put out about 125 cold cranking amps so I potentially have at least 5000w. I want my coilgun to be without capacitors.

Coilgun projectile will be 3/8" or 9.5mm steel ball bearing that is about 3.5 grams.

My goal is to put as many of those 5000watts energy into the projectile without totally saturating it, so what would be best wire gauge and number of turns?

Thanks everyone.

 

Why wouldn't 40v @ 125amp work without caps?

My coilgun will have many stages, like 100 stages, but I don't want caps.

I wish someone would be able to answer my math questions from above

 

Lol no nothing illegal about a coilgun, they are legal in all 50 states and don't even required a FOID card, and I'm trying to avoid capacitors so I'm not on one of those "death by electrocution shows" lol

 

Capacitors are way to big and heavy, my end goal is to make this coilgun portable and to be able to use it just like you would a hunting rifle.

I'm buying super expensive, but powerful and light lithium car batteries for that reason.

If I do it with heavy/bulky capacitors then there isn't going to be any portability in this coilgun so I shouldn't even buy the lithium batteries in that case.

I want to make a better coilgun then what everyone else has already done. I've researched hundreds of other peoples designs, now I want to take what I've learned and make a better one.

 

So at 100% efficiency and 1 meter barrel I could get 560 m/sec or about 550J which is as powerful as most 9mm handguns.

Now I will be lucky to get 20% efficiency so I would need 5x more power or a 5x longer barrel it seems.

Can anyone explain to me difference between using my 40v @125amp batteries, or using 40v caps through same coil? Say the coil has 100 turns and is 3ohms.

Wouldn't both make the same amount of electromagnetism since 3ohms resistance is going to be the bottleneck?

 

I just purchased 120ft, high enamel temp 200c, 14 gauge magnet wire.

I've only bought 2, 13.6v 125amp lithium batteries so far, I will try to purchase 6 or even 8 but need to wait a while.

 

Yea I already looked at the chart, I was just asking a hypothetical question.

My actual coil will be 100ft of 14gauge wire (not yet sure on how many turns that will be) So my resistance is .251 ohms

What is the difference using 40v @125amp batteries OR using 40v capacitors?

I know the capacitors pulse the amps really fast but when you have resistance in a wire the caps and batteries will both achieve same amps correct?

Another questions I have, I know @ high amps batteries have voltage drop. Does that mean when I try to draw 125amps from my 40v batteries that the voltage will really only be like 35v or even 30v?

Thanks guys

 

No I never have, but I'm assuming it goes down just not sure how far down. Maybe to 7 or 8v?