jimmythekid1
04-01-2007, 02:45 PM
I have often heard don't need a fet upgrade for liths, but personally I think a FET upgrade is good insurance. I can't speak for evos since I've never had one, but gen 1 FETS can handle a consistent 2 amps before you run into problems. A normal rwd xmod with stock power supply rarely reaches 1 amp under normal driving conditions. But using some tools or toys I have I've tested to find that a stock xmod can peak over 2 amps for a short time with no problems, the tools I used were a low amps probe and an oscilloscope.
OK lets us an extreme case, ok you have just installed an awd kit, something is out of alignment, causing binding and the car barley moves, then you get stuck on a fly turd and the car won't move. Did I let the throttle go? No I hold it down and try to get unstuck, i do this for a long time, and what do you know my motor is **** hot. So I finally give up and go ahead and fix my awd issue and the **** car still won't move, after further inspection I realized I overheated and burnt my FETS.... So what happened?
All they binding overloaded the motor, the harder it had to try to move the more current it drew, causing it to burn FETS with stock power supply. That is a true story, it happened to me.
Now lets us ohms law
voltage divided by resistance equals amps
6volt/6.66ohms=.9 amps normal running motor RS S2
8.4volts/6.66ohms=1.26 amps running normal RS S2
with liths running normal we are just .74 amps away from possibly doing damage, now if something binds or we get stuck it is much easier to burn FETS.
That is why I always recommend a FET upgrade or V2 with a power supply upgrade.
It may not be 100% necessary but it is good insurance, and good time to modify your board is when you’re adding liths. Also when you get board of liths and a stock motor you will already be set up for a hot motor.
Thanks for taking the time to read this,
Jimmythekid1
OK lets us an extreme case, ok you have just installed an awd kit, something is out of alignment, causing binding and the car barley moves, then you get stuck on a fly turd and the car won't move. Did I let the throttle go? No I hold it down and try to get unstuck, i do this for a long time, and what do you know my motor is **** hot. So I finally give up and go ahead and fix my awd issue and the **** car still won't move, after further inspection I realized I overheated and burnt my FETS.... So what happened?
All they binding overloaded the motor, the harder it had to try to move the more current it drew, causing it to burn FETS with stock power supply. That is a true story, it happened to me.
Now lets us ohms law
voltage divided by resistance equals amps
6volt/6.66ohms=.9 amps normal running motor RS S2
8.4volts/6.66ohms=1.26 amps running normal RS S2
with liths running normal we are just .74 amps away from possibly doing damage, now if something binds or we get stuck it is much easier to burn FETS.
That is why I always recommend a FET upgrade or V2 with a power supply upgrade.
It may not be 100% necessary but it is good insurance, and good time to modify your board is when you’re adding liths. Also when you get board of liths and a stock motor you will already be set up for a hot motor.
Thanks for taking the time to read this,
Jimmythekid1