What is a "GT 2"? Many, many cars have included "GT" (for Gran Tourismo or Grand Touring) in their names, so "GT 2" means something to you and nothing specific to others. For instance, if it is a Porsche 911 GT2, then say that (and in that case it's "GT2", not "GT 2").
Posts by brian_
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Thanks - that makes the situation much more clear.
Bradley GT II
I'm still not clear if you have a GT II (gas engine) to convert, or a GTE (Bradley factory EV) to update.
So it's light and small... and doesn't have much space for battery. Any of the recent VW Beetle projects would provide an example of potential battery choices. At least one conversion company uses a stack of Tesla Model S/X modules behind the rear seat in their Beetle conversions - only a fraction of the full pack - as a low-voltage (by modern EV standards) battery.
To properly select a battery, you need to think about what operating voltage will work for you, how much power you need to get out, and how much energy you need per charge. The voltage will depend on various factors including your preferred motor, and even half of any common modern EV pack will provide enough power to match the performance of the gas Bradley GT or GT II (and beat the GTE), but 100 miles is a lot of range. It might need roughly 20 kWh of battery, which would be an entire Chevrolet Volt pack (a common salvage battery choice).
I ran across a listing for an EV conversion of a GT II done several years ago with a conversion kit:
1979 Bradley GT II Converted: “EV1E”
It uses prismatic lithium cells from CALB, not a salvaged production EV pack... but it has 27 kWh of them. An entire Leaf pack reconfigured for half the operating voltage would be a relatively direct replacement for the CALB cells.
Interesting!
So you wouldn't want to go back to the original low-power motor and lead-acid batteries, or use any original electronic components, but you can put better and newer components in roughly the original configuration (motor mounted to stock VW transaxle, battery boxes each side of motor and in front compartment).
There are other choices as well, including replacing the original motor and transaxle with a complete modern EV drive unit (motor and transaxle). A small Tesla drive unit is an obvious possibility, as you have seen in other projects in progress in this forum.
Fortunately, you can have both more speed (due to higher motor and battery poser) and more range (due to higher motor efficiency and more battery capacity) than the original GTE.
A pretty substantial fraction of the recent posts in this forum are about using Tesla components. It wouldn't be reasonable to rehash all of it in this thread, or even to provide a complete list of links to relevant forum threads. Here are just a couple of long-running discussions of these drive units going into current projects which are mechanically similar (VW/Porsche air-cooled):
911 RSR with Tesla Motor...
1967 VW Split Screen Van - "ICE Breaker"
... and one from the Controllers section about using the Telsa unit:
DIY Tesla Controller
With a Tesla drive unit you still have a transaxle - it's just a single-speed, so no shifting or clutch. The same is true of any other production EV drive unit; the Nissan Leaf is the most common alternative. To me, the main advantage of the Telsa Model S/X small drive unit in this case is that it places the motor behind the axle line, which works well with the VW's semi-trailing arm suspension.
You can use the VW transaxle - without a clutch - as a single-speed by simply choosing the most appropriate ratio and just not shifting it. This is most viable with a modern high-voltage AC motor (due to their wide range of operating speed), but it has even been done with an old brushed DC motor simply by choosing a large enough motor that it provides enough power even when way off of the ideal speed. For instance, a Leaf motor could be mounted to the VW transaxle, leaving the suspension, axles, and the transaxle itself unchanged.
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