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Convert PHEV to pure Electric

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In order to extend the electric range on a PHEV or converting it to run pure on electric, what should be the focus on the conversion? Assuming the PHEV already have everything an EV need (i.e. The motor, drive train, charger and controller), it makes a lot of sense to upgrade the batteries and have a more powerful charger. Is it really this simple?

More to that, I want to buy the new mini cooper countryman PHEV but 20 miles on pure electric is just seem to be enough.
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According to the first article I found about the Mini Countryman PHEV, the electric-only power is only 87 horsepower... much less than the gas engine. That means when running on only battery power the performance is significantly reduced, which is okay because when more power is needed while it happens to have the engine off it probably restarts the engine. As a "pure" EV, it will have both inadequate range (which you fix with more battery), and mediocre performance... which is not so easy to fix.

I don't see the point in buying a new vehicle with an engine, then throwing the engine away. If you could buy a used one with a dead engine, that would make more sense, but if you're buying new, why not just buy one with the desired design?
 

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Mechanical power is the product of torque and speed. For more power, you can increase torque at the same speed (such as a bigger motor operating over the same range of speeds), or increase speed at the same torque (such as a motor of the same size but able to run faster, using more gear reduction), or increase both.

For higher speed at the same torque from a motor you need more voltage (while maintaining or increasing current)... so in addition to a battery with more cells in series, you would likely need to replace the controller (inverter, assuming the motor is AC). If the existing motor cannot safely turn faster, or can't handle more voltage, a higher-speed motor will be wound differently. Other forum members with more practical experience can fill in details.

To increase torque from any electric motor you need more current, and more voltage to make the higher current flow; how far you can go is limited by what the motor can take, and what the controller can provide... so in addition to a battery with more capacity and likely more voltage you would likely need to replace the controller/inverter for a substantial torque increase. If the motor is already maxed out for torque, a motor able to put out more torque will be bigger (longer, larger diameter) and heavier. Again, other forum members with more practical experience can fill in details.

Whether a power increase is due to more speed or more torque, more power out means more heat generated (due to less than perfect efficiency), and so more cooling requirement. There is a reason that modern production EVs typically have liquid-cooled motors (and controllers, and often batteries).


The capacity of a transmission is primarily a torque limit; they can usually turn moderately faster without much problem. If all you need is more gear reduction, you drive in a lower gear... except for vehicles with a single-speed transmission, which is every production EV. In hybrids with one axle driven only electrically (that's the rear axle in a Mini Countryman PHEV), the transmission only has one speed, and no other ratios are likely to be available.


As with the engine, I don't see the point in buying a new hybrid vehicle and replacing all of the major components of the powertrain - you might as well start with a gas-engined car, and that might as well be used.
 

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In order to extend the electric range on a PHEV or converting it to run pure on electric, ....
More to that, I want to buy the new mini cooper countryman PHEV but 20 miles on pure electric is just seem to be enough.
First,..... be clear on what you want to do.
Is it an extended range PHEV, or a pure EV with no ICE ?
.....there is a big difference. !
 
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