question for electronic guru's

[shaunjohnson]

i dream of an electric 1:1 car (my nissan manette to be specific)...but getting a MMM big enough is a problem

how about this though...
MMM or even a sidewinder...the 3 phases of that are then instead used to turn on/off MEGA fets...like massive!! large power transistors even.

now as far as i know that would work for the startup phase of the motor, how could one get the back EMF required for the original ESC to adjust it's timing?

the OTHER idea would be to get just the brain board from say the monster, then make a power board to the same specs as the original but with the mega fets and drive that with the MMM's brain board.
dont worry about where the mega fets come from but i just wondered if it could work
shaun

[brijar]

Hey that sounds awesome! I've thought of this in the past while dreaming about an electric Mustang. I would like to add that instead of using said MEGA fet's with the original brain board, just use several hundred or even a thousand regular FET's with lots of heatsinks.

I'd be very interested to learn if this is possible as well, even though I've tried to calculate the number of batteries needed, and I keep coming up with like $10,000 in Dewalt 36v packs -.-

Thanx,
Brijar!!!

[JThiessen]

Try looking for an episode of Monster Garage where they converted a mustang to electric and they used about 200 milwaulkie cordless batteries for power. You might find some info on the ESC system they used.

[eovnu87435ds]

The theory you have is possible. If you look around for a Mamba Max Mod1, it is where they take two of the MM fet boards and put them in parallel to double the amperage it can take. For something this size, I think the low speed cogging would be quite bad. Unless you plan to race with the car, I think your best bet is to have it be sensored 100% of the time

[shaunjohnson]

from what ive seen in castles ESC's, cogging is next to nothing.
added to the fact that the motor chosen will have LOADS of poles, hence reducing cogging to next-to-nill.
lots of little fets might work but i'd rather mega fets if they are avaliable.
fets job is to take a small electrical signal and switch on some serious power. so a mega fet might take 10A on the signal to switch it...i wouldent know!

my manette has tons of space under it for batteries, so no internal space would be needed to be taken up. once the fuel tank is gone (80 liter) then there is about 2 square meters of total space under there. must measure that some day.
i'd love this project, sure people have made electric cars and some are pretty damn fast...but that was BRUSHED!!!.........AND LEAD ACID BATTS!!!! and to me that's silly.
so i want A123 cells all the way baby, A123 systems have cells avaliable for large projects like this.
i can see it now, the old shat box that usualy sits in the corner of the school carpart that is always leaking diesel, suddenly just starts rolling out of the carpark with no engine going...

[BrianG]

Originally Posted by shaunjohnson

...lots of little fets might work but i'd rather mega fets if they are avaliable. fets job is to take a small electrical signal and switch on some serious power. so a mega fet might take 10A on the signal to switch it...i wouldent know!...

Using many FETs decreases the on resistance for better efficiency. A single large FET may not have ideal resistance, switching speed, etc as many smaller ones placed in parallel. And, FET gates are voltage driven (very little current). I like to think of FETs like a garden hose where the input and output is the hose and the gate is a set of fingers squeezing it to limit/stop current.