[judebert]

Just here to vote for the name: Hemi.

"You got a Hemi in that thing?"

Awww, yeah.

[etischer]

Wow, that is pretty sweet. nice attention to detail. Does one fan blow in and the other blow out? You're a great inspiration to all us diy folks.

[Tesseract]

Originally Posted by major

You might want to have those copper plates plated. I have used tin for copper bus bars...

For standard bus bars that are separated by inches I would totally agree with you, but the two plates here are only 0.01" apart and pure tin has a bad habit of forming whiskers while tin/lead plating (ie - solder), which doesn't whisker, is no longer permitted because of the RoHS directives in Europe... It does make for quite a dilemma...

[Tesseract]

Originally Posted by JRP3

Nice, what are the physical dimensions?

Big and heavy?

Without the mounting plate (size not yet determined) it is approx. 18.5" long by 7.75" wide by 4.5" tall (not including the fans, especially since they might get thicker). It weighs about 28 lbs as of now. I definitely wouldn't want to drop it on my foot!

[major]

Originally Posted by Tesseract

It does make for quite a dilemma...

How about nickel? My 5 cents worth

[Tesseract]

Originally Posted by major

How about nickel? My 5 cents worth

Funny... we were just discussing that as a result of your post and my response... And we decided that nickel might be the way to go. One of the requirements is that we have to be able to do all of the assembly in house because as soon as we send something out the price triples (like having the copper plates cut by waterjet - $80 per set... )

Anyway, if electroless nickel seems feasible for us to do in-house then that is the one that looks best overall (so we are in agreement again... hmmm.. either I'm getting smarter or you're getting dumber, major... ).

[dimitri]

Originally Posted by Tesseract

Big and heavy?

It weighs about 28 lbs as of now. I definitely wouldn't want to drop it on my foot!

28 Lb ??? well, we can call off the name contest, BigMoFo it is...

[JRP3]

Originally Posted by Tesseract

For standard bus bars that are separated by inches I would totally agree with you, but the two plates here are only 0.01" apart and pure tin has a bad habit of forming whiskers while tin/lead plating (ie - solder), which doesn't whisker, is no longer permitted because of the RoHS directives in Europe... It does make for quite a dilemma...

Tin plus a thin plastic sheet between them? Do they have to be that close? Couldn't current jump between them?

[Tesseract]

Originally Posted by JRP3

Tin plus a thin plastic sheet between them? Do they have to be that close? Couldn't current jump between them?

Polyester (mylar) has a dielectric strength of 1kV per mil, so that 10 mils is good for 10kV. It's actually pretty tough stuff.

But there are some very good electrical reasons for putting those plates as close together as possible: it helps the magnetic fields from the outgoing and incoming currents to cancel out (minimizing radiated noise) while the mylar film in between the plates forms a low value (1000pF or so) capacitor that will reduce switching noise and transients.

EDIT - just noticed you quoted the tin whiskers post. Yes, tin plating would be a bad idea in this instance because the whiskers will eventually cause a short circuit. More than likely the current capacity of the battery pack will be enough to "clear" the short (that's an engineering term that really means "vaporize" it ) but who wants tin vapor floating around their motor controller? If you want to see some scary stuff do a google search on tin whiskers...

[JRP3]

Originally Posted by Tesseract

Polyester (mylar) has a dielectric strength of 1kV per mil, so that 10 mils is good for 10kV. It's actually pretty tough stuff.


EDIT - just noticed you quoted the tin whiskers post. Yes, tin plating would be a bad idea in this instance because the whiskers will eventually cause a short circuit.

Gotcha, I didn't realize you did use plastic between the plates already, I thought it was bare plates that close