FAQs
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They’re light - 2,214 lbs - which means less mass for an electric motor to move around.
They are fairly aerodynamic - .038cd - which helps at freeway speed.
You can find them used in good shape inexpensively.
Most have manual transmissions, which is required for an electric conversion.
Being a convertible, in most climates they don’t need air-conditioning.
Most are well cared for - they were an "it" car that some people gladly paid a premium for.
Parts are easily available, including body kits, low profile headlights, roll bars, etc.
Their styling is classic, some say iconic.
They are fun to drive!
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The Farication Diagrams includes plans for all the pieces that need to be fabricated to fit the Miata:
- Nose Rack
- Top Rack
- Trunk Rack
- Motor Mounts
- Controller and Charger Bracket
- High Voltage Enclosure Bracket
The motor, controller, charger, batteries, etc. are all available off the shelf from a number of suppliers including donor vehicles.
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Absolutely! Your build might need larger or smaller battery racks or relocated components. The important thing to consider is the space the racks can occupy, and the available mounting points.
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You certainly could, and a lot of people do. But with off-the-shelf products you'll have installation guides, warranties and tech support to help you.
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Once the components are fabricated, the kit can be assembled using common hand and power tools. There are two tools required that most people don't have in their shop which can be either rented or borrowed.
- Engine Hoist - this is used to remove the engine from the car and to install the motor. It's a common tool for home mechanics and can be rented from most tool rental shops
- Cable crimper - this is used to make your battery cables. This is a less common tool, but you may be able to rent one, or borrow one from a local EV club.
Also, our kit doesn't require removal of the gas tank for two reasons:
- Removal of the Miata gas tank requires the rear subframe (differential, rear suspension and brakes) to be removed. This is a big job that would be best to avoid.
- We didn't want to put batteries in the cockpit for safety reasons.
With our kit the gas tank is drained but remains in place. It's not heavy enough to negatively affect the car's performance. Weight distribution is maintained by balancing the pack between front and rear.
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There are a number of factors that will determine how long a conversion will take:
- Your welding skills
- Your mechanical abilities
- Availability of parts
- Availability of tools
- Your schedule
If you have good mechanical skills, all the parts, all the tools and could devote 8 hours a day to the project, it's estimated to take 8 - 12 days to complete the project. If you have average mechanical abilities and are planning on working on the project only during weekends, plan on 4 - 8 weeks to complete the project.
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In round numbers, the entire conversion will roughly cost from $12,000 to $26,000, depending on the battery type, options, whether you are buying new or used components and if you currently own an early Miata or not.
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No, the kit uses the standard 5 speed transmission. Direct drive (no transmission) has its advantages, but it is a compromise: top speed is limited and it takes a lot of current to climb hills. In order to have the best drivable result, we decided to keep the transmission. You'll keep it in 2nd around town and 3rd or 4th on the highway. It drives a lot like an automatic - since the motor doesn’t idle you rarely need to use the clutch.
As an option, you can choose to go clutchless. This option doesn't use a flywheel, so it reduces the weight and drag on the motor substantially. Shifting requires a little more attention than when using a clutch, but a lot of EVs are setup this way and for the most part, the owners are quite happy with it.
The Soliton1 controller has a setting that will make the motor "idle" - spin at low speed rather than stop. This spinning allows the automatic transmission to function normally. Naturally this extra spinning of the motor will impact the range as will he automatic transmissions reduced efficiency, but if a manual transmission is keeping you from going electric, this may be the answer.
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Depends on the battery pack you choose. The Lead Acid version gets about 20 miles per charge with a DC motor and controller or about 25 with an AC motor and controller. Lithium options can go up to 90 miles on a charge. Your range of course depends on the batteries you use, your terrain and driving style.
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Charge time depends on the rating of the charger used and the size of the battery pack. For example a 3.3KW charger will take about 5 hours to charge a 15KWh Battery pack (3.3KW x 5h = 16.5KWh). A 6.6KW charger would take roughly half this time. One thing to note, since most charging is done after midnight when the utility rates are (usually) the lowest. A 3 hour charge time may not provide any real advantage over a 6 hour charge time, unless you need to drive to work at 4:00 AM...
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Our unique motor mount system allow for a wide variety of motors to be used with our kit. Rather than connecting the motor directly to the car, we connect the transmission bell housing/adapter plate to the car, allowing motors of various dimensions to work. With a standard Nose Rack installed, 18" length and 10" of width are available to the motor. The Nose Rack can be modified to allow for a longer motor.
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Our kit was initially designed to support low-cost AGM lead-acid batteries. These are commonly used in schools and colleges as performance is secondary to cost. With minimal modification, our battery racks can support off-the-shelf prismatic lithium batteries (CALB, Lynx, etc) or cells from a donor electric car (Leaf, Volt, Tesla, etc.)
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No, you don't have to upgrade the suspension since the battery pack isn’t heavier than the Miata's GVW. Plus the weight is well distributed. We do lower the front sway bar 2" to clear the Nose Rack.
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In an ICE car, the power brakes work off of the engine’s vacuum. In an electric car, we need to add a vacuum pump to create the vacuum. The vacuum pump mounted below the battery rack on the passenger side beside the motor. It is plumbed to a vacuum switch, so when the brake booster needs more vacuum it turns on to keep the brakes working.
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Miatas come with both manual and power rack-and-pinion steering. Rack and Pinion is a very efficient design and, though the front of the car is heavier than stock, it's quite manageable with manual steering. Most conversions will either use the manual steering or if the car came with power steering, remove the power steering pump and loop the lines back to the steering box so that it doesn't run dry.
If you do need to go with power steering, there are a couple of options:
- You can add a small electric motor to drive the pump or put a pulley and belt on the tailshaft of the motor.
- The Toyota MR2 had an electric power steering pump that could be used. I understand these are available from junk yards and from auto part stores. You can also buy a complete kit to add power steering. As for placement, there is room under the Nose Rack or beside the IOTA DC/DC converter. Another option is to mount the pump where the vacuum pump is located - under the Top Rack on the passenger side - and move the vacuum pump to another location.
- Even with an electric pump, power steering will impact your range. We would recommend choosing a battery option that had at least 25% additional range to provide adequate power.
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In general, air conditioning systems take a lot of power. One of the reasons a Miata makes such a great electric conversion is because it is a convertible. Hot weather is a good opportunity to put the top down and enjoy the breeze. Another option is to leave the top up, but lower the windows and unzip the back window. This will keep the sun off the occupants but allow the air to flow through the cockpit.
If you live in an area where air conditioning is a necessity, then you may want to consider adding a 12v compressor that could be run off the SLI battery.
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A heater of some sort is needed to defrost the windshield and warm the interior in cold weather. An ICE car is warmed by the waste heat created by the engine. This heat is transferred to the cooling system which is connected to a small radiator (heater core) mounted under the dash. Since an electric car doesn’t have any waste heat, another solution needs to be devised. You can replace the heater core with a ceramic heater unit or, add a small electric water heater and pump to route the heated water through the heater core.
Another option is to use heated seats. Heated seat pads are available on Amazon that can be inserted in the seats under the upholstery.