I want to upgrade the old ecoMetro. (Unite 500W 36V)
Looking around here I see a Currie MOT-SD 36750 motor at 750W. I'm thinking this one because it's short. On this scooter the motor sticks out sideways so with a case size that's about same as mine hopefully it won't stick out worse. Also, the Currie appears to have the same 3 7/8" OC three point mounting. (maybe I could mount a different motor but it would probably stick out farther)
I'd like to know what all parts are needed. I assume along with a motor there's a controller and throttle, and maybe other things.
I'm a reasonable mechanic and I like keeping things simple. Is this as simple and easy as I think?
For more speed a more powerful motor and controller along with a higher gear ratio achieved by installing a smaller sprocket on the rear wheel would do the job. Over-Volting the original motor with a higher Voltage battery pack and controller would also achieve more speed however that could overheat and burn out the original motor. The larger motor and higher gear ratio method is the most reliable way to get more speed.
Regarding gaining more distance, if the scooter is made to go faster the distance that the original battery pack will provide will be decreased. In order to have the same distance when upgrading from a 500 Watt motor to a 1000 Watt motor the battery pack capacity would most likely need to be doubled, and to get more distance with the 1000 Watt motor than with the original 500 Watt motor the battery pack's capacity would need to be increased even more.
The EcoSmart Metro's original 30 Amp controller should be able to handle a 1000 Watt motor on Central Florida's flat roads, however it will not provide the full power that the motor can produce and will limit is power by around 25%. A 36 Volt 40 Amp 1000 Watt controller would allow the motor to run at its full power level. The original 30 Amp controller would allow the scooter to travel more distance on a single battery charge than a 40 Amp controller though.
We have LiFePO4 batteries that dimensional wise would directly replace the EcoSmart's original batteries, however our 12 Volt 7.5Ah LiFePO4 batteries are rated for a 15 Amp maximum discharge current so they can not safely output the amount of power that the EcoSmart uses in either stock or upgrade modified form. I do not know where to get Lithium batteries that can handle a 30 or 40 Amp load however this does not mean they are not available somewhere. Our LiFePO4 batteries can be recharged with any lead acid battery charger because they have a built in battery management system. Other Lithium batteries may or may not have a built in BMS.
I do not know specifically where to purchase a brushless replacement motor for the EcoSmart, however do know that we are planning on having a larger variety of brushless motors in stock for next year.
To achieve your goals of more speed and longer distance I would lean towards custom installing a 36 Volt 1000 Watt motor (MOT-SD36100), 55 tooth rear sprocket (SPR-2555), 36 Volt 40 Amp 1000 Watt controller (SPD-CT660B9), and a 36 Volt battery pack made of six 12V 15Ah batteries (BAT-12V15A). Due to space limitations the extra three batteries would need to be placed somewhere outside of the scooter's frame like on top of the footplate, or on the rear rack. The extra capacity battery pack would require a larger battery charger such as a 36 Volt 3 Amp charger (CHR-36V3AXLR) in order to recharge them overnight.
Please let me know if I missed any questions or if you have any further questions.
All of our freewheel hubs that chain sprockets bolt onto are the same size. SPR-2555 measures 4-1/2" OD x 2-1/8" ID and is a direct replacement for the Razor EcoSmart's original 65 tooth sprocket - it will bolt directly onto the existing freewheel. We have a new Chain Length Calculator which can be used to determine what size chain is needed when installing different sprocket sizes. It is recommended to replace the old chain with a new chain when installing a new sprocket because old chains stretch out over time which can cause new sprocket to wear out faster than they should.
If you use the original motor and modify the battery pack from 36 Volts to 48 Volts then the motor will spin faster at 48 Volts than it does at 36 Volts so the wheel sprocket will not need to be changed to have an increase in top speed.
The EcoSmart's original 36 Volt battery pack could be increased to 48 Volts and then you could use the scooter to see if the controller and motor will handle the extra Voltage. If the scooter is only used on flat ground there is a good chance that it will. If the original 36 Volt charger was replaced with a 48 Volt charger then it would charge the 48 Volt battery pack without the need for a second 12 Volt charger and taking off the bamboo footplate.
A larger motor sprocket would increase the number of chain links needed for the modification however it would also make the gear ratio higher. The gear ratio and top speed needs to be kept in line with the power of the motor so the motor can run near its top RPM and not be lugged. If the motor is lugged its power output will be significantly lowered and lugging could also cause the motor to overheat and burn out. The EcoSmart's original 18 MPH top speed is a perfect match for its 500 Watt motor. The original 500 Watt motor spins at 2250 RPM and with the scooters original 5.91:1 gear ratio and 16" wheels it has an 18 MPH top speed. If the original motor was ran on 48 Volts then it power would increase to 887 Watts and its shaft would spin at 3000 RPM and with the original 5.91:1 gear ratio the scooters new top speed would be 24 MPH. Traveling on a scooter at 24 MPH requires 812 Watts of power on flat ground so for flat ground riding 24 MPH would be a perfect top speed for the scooter if the motor's Voltage was increased to 48 Volts. To put this into more simple terms do not change the sprocket sizes if you upgrade the battery pack to 48 Volts.
The reason it takes an extra 387 Watts of power to go that extra 6 MPH is that drag (air resistance) significantly increases between 18 MPH and 24 MPH.
Here are my resources for the calculations above: