eco-ants --> eco inventing <-- - Electric Car -
This is my home built electric car.
My electric car has been designed as a low cost city car, with a top speed of 80 km/hr, and a range of 50km.
This is perfect for my country, where 2/3'rds of people commute less than 10km, and 77% of the electricity is generated from renewable sources :)
I charge the car at home using night rate electricity, and it has zero polution !
Yes ZERO polution :)
In New Zealand 77% of our electricity is from renewable sources.
This number is averaged over the year, in reality it is changing all the time, depending on the load.
At night they turn off the expensive coal and gas powerplants, leaving the hydro, wind and geothermal plants running. Therefore if I charge my car at night, and drive whenever I want, I produce zero emmisions :)
This is very improtant to me, and since we share the same atmosphere, it should be improtant to you :)
My electric car has a 72v battery pack, running a 400A controller into a Mars 1003 brushed, permanent magnet motor.
These motors are very simple, cheap and available here
on the web for less than US$750 !
The Motor is connected directly to the gearbox shaft, there is no clutch.
There is actually no need for a clutch when you don't need to keep a combustion engine idling. Electric motors are fine with starting and stopping, in fact it saves energy at lights when you don't need to keep a motor running.
In a traffic jam people in combustion cars can run out of fuel, not so in an electric car. Electric cars only use energy when they are propelling the car forward.
No idling, No wasted fuel !
Idling gets ZERO miles per gallon.
Electric car heater design:
An electric engine doesn't produce the kilowatts of waste heat that an internal combustion engine produces. Thus an electric car has to look elsewhere for heating.
I'm designing a heater for my e-car, balancing the cost, complexity and safety. I'm also keenly aware that I don't want to use too much power from my battery pack.
Many home built electric cars these days use ceramic heater cores. Ceramic heaters are great,they provide instant heat and are safer than resistive heating elements due to their lower temperature.
However for my lower than standard battery pack voltage, they aren't an option.
My plan is to keep the original heater core, and heat it with an off the shelf truck engine heater.
How much power do I need ?
To keep my electrical power useage low, and still retain a fast heating time, I'm going to have to keep the water volume low.
To heat 1ml of water 1`C requires 1 Cal of energy.
1 Cal = 4.18J
Thus to heat 500ml of water up by 20`C, I will need 500*20*4.18 = 41800 Joules
To convert this ammount of energy, to an electrical power input, I need to divide by time.
Because 1watt = 1joule / 1second
(Joules are a measure of energy-has units of time, but watts are a measure of power-no units of time).
However power multiplied by time gives energy :)
Now 1 Joule = 1 watt for 1 second,
so to do all this heating in 1 second will take 41,800w !!!
But if I heat it over 30 seconds,
It will only require 1,400watts.
This is very manageable, using my pack voltage of 72v, it is only 20amps.
This will give me adequate heating, faster than an internal combustion car, and not reduce my range much at all :)
How to build such a heater ?
I've trawled the web looking for a pre-existing product that does a similar job, since it's always cheaper to buy something that is already mass produced !
I've settled on a non-pumped, truck engine pre-heater
from the USA.
The 120v 2000 w version will provide about 1200w of heating from my cars 72v DC.
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