Crystalyte 4840 with TO-247 fets

[Farfle]

Planning on putting 6 of these IRFP4468PBF Fets In a crystalyte 4840 12-fet board, It has been modded with a CA tap, regen, and to run high-voltage, it has 100v caps 10ga wire etc... About the Fets, There are better Fets out there for sure, but from what I could find they are the best cost/performance for a large package fet. 7 bucks gets you a 100v 2Mohm Rdson, 195a package limited, 290a silicon limited fet with very similar gate characteristics to a pair of 4110's, but should give a slight reduction In on resistance, zero current sharing problems and a much better thermal pathway. The Fets will be spring-clipped to a piece of 1"x 3/16" copper bar with several laptop heatsinks soldered to it.hoping to have it look something like this: (picture soon) can any of the super controller savvy people comment on this?

heres the datasheet:

http://www.irf.com/product-info/datasheets/data/irfp4468pbf.pdf

 

[number1cruncher]

Does this controller normally accept TO-247 FETs? Or are you going to modify the board?

 

[Farfle]

Does this controller normally accept TO-247 FETs? Or are you going to modify the board?

Nope, normally a standard to-220 controller, im taking every other fet out, turning a 12-fet into a 6-fet. I drew it all up in a cad program and they will fit, not in the existing box however.

 

[CamLight]

Farfle, I'm not sure you come out ahead using six IRFP4468's vs. twelve IRFB4110's. Comparing two 4110's to a single 4468, I get the following numbers:

Theta-js
4110's = 0.45C/W
4668 = 0.54C/W

Rds-on (typ @ room temp)
4110's = 1.85mOhm
4668 = 2.0mOhm

Continuous Current (wire bond limited)
4110's = 240A
4668 = 195A

Total Gate Charge
4110's = 300nC
4668 = 360nC

For all the specs, it appears that a pair of 4110's beats out a single 4668.
I haven't compared prices though and six 4668's could share current better than twelve 4110's (perhaps only if the board is redesigned to be smaller though). And, of course, a single 4668 takes up a lot less room than the two 4110's.

 

[Farfle]

Sorry for the confusion, the Fets this controller is built with are 4310s, these guys: http://www.irf.com/product-info/datasheets/data/irfs4310.pdf

Will do some test-to-destruction with the 4310s to see how much they can really take, then ill replace them with the big guys and test them to almost-destruction . dont want to blow them up just yet.

 

[boostjuice]

18FET board modded to 12x TO-247 package FETs = worthwhile upgrade
12FET board modded to 6x TO-247 package = going backwards

 

[Farfle]

hmm, it may be a small step backwards. but the Fets are already on the way, hopefully ill be pleasantly surprised. If not, it at least proves that its dooable

 

[heathyoung]

Have you considered the gate capacitance? Some of the drivers on these controllers are pretty wimpy.

 

[FAS]

Hello!

I realise that idea in my infineon after its blowing !
blowup

preparing aluminum base

forming FET pins

mounting FETs

this show general idea of mounting TO247

sorry for my bad english.
more details in our e-bike forum http://electrotransport.ru/ussr/index.php/topic,5513.msg138345.html#msg138345

 

[heathyoung]

You did that on 12 series? What sort of current were you running!

Interesting mod - with the condition of the board I would have tossed it myself

Still running the original caps? Thats the first thing I changed on mine - to very low ESR caps

Link for anyone else whose Russian is a little rusty

http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Felectrotransport.ru%2Fussr%2Findex.php%2Ftopic%2C5513.msg138345.html%23msg138345&act=url

Edit: UGH - google translate's Rushlish is almost as good as Chinglish...