So just as an update to where all this was left.. In random intervals I've made progress, then lost more (on repeat) until what you see it looks like now. I will say it did look pretty nice at one point but was too slow so tore it back down and re-did batteries, control circuitry, etc..
So to explain the pictures: it has a boat seat because the bike seat was painful and made it look even worse, got a red and black paint job because the little kid colors were repulsive, had/has a 555 PWM based throttle (potentiometer sticking outta handlebars), has turf tires for maximum awesome, a ~17:1 gear ratio using jackshaft, a 1HP brushed DC treadmill motor rated for 95v... Just whatever was lying around
Electrics:
2s2p 20V drill battery pack tied to 3s5p LiIon pack (lots more in the mail) which gets about 54-56 volts max and around 25 Amps (~1.4KW). The positive end goes into the motor and low side switching is done through various plug and play parallel MOSFET banks that I'm testing, those are controlled by a derivative of some generic MOSFET driver circuits that I sketched up because this microcontroller operates at 3.3v and is active low. The power has gotten to such a ridiculous level at this point that I've resorted to a pair of IRFP260n MOSFETs for lower on resistance and upped the gate voltage/current peak! The microcontroller is an ESP8266 nodeMCU, (which only has one ADC interface pin so a separate BMS is in the works) which is used to drive the .96" OLED display, calculate PWM duty cycle from accelerometer input, read battery voltage to prevent damage, and hopefully in the future monitor current, temperature and whatever else sounds like fun..
Problems... of course
Right now it works great, but top speed is very slow because of gearing and voltage. The most annoying issue is dead MOSFETs, while the control circuitry is as efficient as possible, the FETs can't seem to handle more than 40 volts for whatever reason! It is driving me insane to troubleshoot because changing them out for higher power components has no new effect. It must be the driver circuit but I'm more interested in what equations I could use to explain the issue in terms of gate to source voltage, and turn on time in nanoseconds for the driver <-(which must be the problem)
All of this is to be expected while reinventing all the wheels humanly possible in controlling brushed motors but how else will I learn if not by wasting money on roasted parts?! lolol
Funny story though, my neighbor took it off-roading and the MOSFET overheated; this jammed the motor at full power whilst the little 12 year old was trying to hold on for dear life to unplug the battery.... Dude that kid got dragged across my neighbor's (was perfect) yard for so long before reaching that connector
The bottom pic is of a MOSFET H-bridge with the driver circuitry on board that I want to use for a brushless/induction motor, really interesting motors that don't see much use in electric vehicles for lack of research funding but have huge potential in both efficiency and in the virtually infinitely variable magnetism of the ferrous core. Tesla's website literally says that they are better than brushless motors in every way but would cost too much in R&D to implement effectively.
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