Fets in Xmod evo getting warm

[HACHI-RYOKU]

I put some fets in a Xmod evo. A stack of 2X3. I'm running a plasma-atomic with neo mags in it. The fets get hot. It doesn't blow the fets, but at one point it melted the solder on some of the fet's pins and it shorted out with the pin next to it when I slammed into a table leg. This was all on the output side of the 9910's. The fets didn't blow. They wanted to but the batteries were running out of juice and I caught the problem early. I fixed it and it's running like it was before. It still gets hot around that area though, so I lifted the metal motor contacts that touch the top of the fets. I figured that if they are getting hot, then they're just contributing to the problem. I also replaced the motor wire with longer and thicker wire. The area is still getting hot though. Otherwise the car is fast as hell. It's AWD and it has the highest stock gear set.

Anybody have any essay on this? I was thinking I might need to reduce the gear ratio......maybe? Anybody else getting this problem?

[Clint]

<-same setup

Plasmatomic is just a tad hot for a fet mod. Lowering the gear ratio
will help. As far as it melting the solder, use some higher temp solder
than what you have. Lowes or Homedepot will have an assortment.
using it as a racer it should be fine, but if you are crawling with it and load the tires it could fry the fets when it stalls.

Possible safety solution:
cut the leg on the fetstack for V-in to separate it from the board, wire in a small inline fuse to each stack, i would try 5A at first but if that blows bump it to 7.5A fuse. Not sure which pin off hand but you can get the pdf for the fets on any parts order site. digikey, newark.com etc.

Another idea i had was to use a small peice of copper between each fet.
have it stick out some so air can flow over the copper strips. use thermal
glue between each fet/copper connection so that the copper doesnt slide
and short the stack. you can buy thermal glue from most PC enthusiast
websites. newegg, hardcorecooling, artic cooling.

[HACHI-RYOKU]

Thanx Clint. All good info. I've got a Nelly Evo that's due in now any day. That may fix it.

I was trying to see if I could just run it with a fet stack in lue of an external turbo for testing purposes, but I've just about finished all my tests. This thing has the potential to race a MR-02 with like mods, but if I have to lower the gear ratio, it just becomes another 1:28 car that can't go head to head with my MR-02. The only thing keeping it in the game now is the acceleration and handling. If I have to give up more top end speed though the MR-02 will overtake it too quickly. Right now, with it's current set up, the MR-02 beats it on the straight away, but the EVO can keep pace with it on the corners. In fact it seems like it's cornering better than the MR-02, but only with the AWD. I need to do some more head to head racing to confirm this. Which means I need to get with my friend and race him. Gotta get that track time!