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My upgrade from DC to AC drive has prompted a lot of questions. I'll try to answer some more here. The old versus new motor comparison pictures can be seen on the "Where" page. The new AC brushless 3 phase induction motor provides much higher starting torque, regeneration and should also be about 10% more efficient. It certainly runs a lot cooler than my old DC one. It does however weigh about 2.5X as much as the old DC one. |
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Motor in situ on 5mm steel support welded to chassis. Motor support can be unbolted and dropped down using a trolley jack. Motor angle also adjustable to align with prop shaft and differential. |
Motor sits on a 10mm rubber mat and is vibration insulated from the mounting to reduce noise. |
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No gearbox! Motor connected directly to diff with custom short prop shaft. |
The 28x9mm Plywood compression supports ready to install. One for each cell. |
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"Habistat" Pulse proportional control battery heater controller. Provides very economic accurate heating of battery compartment when used to control under cell heating element. Heater is rated at 150w and to maintain 20C in ambient of 5C uses about 1kwh daily, but makes batteries much more lively in terms of charge and discharge ability. Thermostat is adjustable from about 18 to 32C |
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General upgrade issues. Sourcing a suitable AC system was quite a job, I considered the high voltage Siemens, Brusa and low voltage Curtis systems, before deciding on the Zapi. I eventually went for the Zapi as it allowed a higher battery voltage 96v versus the Curtis 80v. It is however not as flexible, and may not have been the best choice. The Inverters have to be programmed to suit the motor, and neither Zapi or Curtis would supply an inverter without a motor as well. The Curtis motor quote was over twice as expensive as the Zapi. Both inverters were similarly priced. Total cost of Zapi 96v 350A AC Inverter and 96v 12kw AC motor was £2000 inc delivery and taxes. The upgrade used low voltage components. and I was able to reuse things like my old contactor, charger, dc-dc converter etc, and I preferred the safer lower system voltage. The Zapi Inverter was designed for forklifts and the like, and it's speed control is very tight. It does not seem to allow coasting which is a shame, I might modify it to allow that if I can. It's a bit like driving with permanent cruise control. You select your speed it accelerates up to that, and then keeps it pegged at whatever you set, drawing more current going uphill and regenerating when going downhill if necessary to maintain your set speed. I am adjusting my driving style to accommodate it, and I will do a range test as soon as weather improves. The Zapi does have a fair amount of programming options, and you can adjust max speed and current to prevent people who might borrow your pride and joy crashing it! I'll report back on which goes further the old DC or the new AC. Note I had to drop from 30 to 28 cells to use the AC system as the final voltage was too high using 30 cells. So I have lost 10% capacity but hopefully gained 10% efficiency with AC and regeneration. Anyway I'm still learning. Good luck with your own projects. Comments always welcome. Please report website problems, broken links etc. Regards Peter Perkins
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Click here to download my DC-AC upgrade photo selection zip archive. (4mb file) |
Click here to download the Zapi AC3 Inverter Manual. (1.3mb file) |
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Click here to download the "Best" AC 12kw Motor spec and torque sheets. (600kb file) |
Click here to download the "Habistat" thermostat manual. (200kb file) |
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Click here to download the "Supercapacitor" Auxiliary 12v battery replacement. (350kb file) |
Click here to download the old Advanced DC motors spec and torque sheets. (35kb file) |
