I did some research on a hypothetical design for a cheap charge meter and billing system. Basically, charge-point costs $6,000 which seems like far too much.
This is not something I plan or want to do, just a hypothetical. Just because it could be build doesn't mean it should be.
The way it would work - you pair your phone with the charging station, and use an app to authorize the charge. The device uses an electromagnetic relay switch rated for 240V 30A to open an outlet or wire to a charger. The current is measured using the ACS712 current sensor for Arduino and sent over ethernet to the billing system.
So in theory (not 100% familiar with bluetooth specs), you walk up to the charging station that you've already authorize, then open the app and press "charge. The unit itself would be covered somewhere - no physical interaction.
Parts:
Arduino w/ Ethernet ($40)
Electormagnetic relay 30A (MGN2C-AC240) $50
HiLetgo 2pcs ACS712 30A ($7.19)
Bluetooth (DSD TECH HC-05) $8.49
Total $105.68 plus assembly, plastic cover, misc parts. Maybe sells for $200-$250, plus 5-10% commission to support billing infrastructure. Target would be apartment building owners, workplace owners, and workers/tenants looking to convince. They'd be able to make a profit off the electricity to pay for the installation and just to make a profit.
I'd have the skills to make it work, but I'd rather someone stole the idea. The business details and liabilities are not small, and I have my full time job which is enough. I suppose if I keep thinking about it, I'll have to make a prototype and a kickstarter.
Also, I'd posted something (not the same exactly) in "supercharger infrastructure" but seems no one there interested to respond. This is after all for the M3 primarily in mind.
This is not something I plan or want to do, just a hypothetical. Just because it could be build doesn't mean it should be.
The way it would work - you pair your phone with the charging station, and use an app to authorize the charge. The device uses an electromagnetic relay switch rated for 240V 30A to open an outlet or wire to a charger. The current is measured using the ACS712 current sensor for Arduino and sent over ethernet to the billing system.
So in theory (not 100% familiar with bluetooth specs), you walk up to the charging station that you've already authorize, then open the app and press "charge. The unit itself would be covered somewhere - no physical interaction.
Parts:
Arduino w/ Ethernet ($40)
Electormagnetic relay 30A (MGN2C-AC240) $50
HiLetgo 2pcs ACS712 30A ($7.19)
Bluetooth (DSD TECH HC-05) $8.49
Total $105.68 plus assembly, plastic cover, misc parts. Maybe sells for $200-$250, plus 5-10% commission to support billing infrastructure. Target would be apartment building owners, workplace owners, and workers/tenants looking to convince. They'd be able to make a profit off the electricity to pay for the installation and just to make a profit.
I'd have the skills to make it work, but I'd rather someone stole the idea. The business details and liabilities are not small, and I have my full time job which is enough. I suppose if I keep thinking about it, I'll have to make a prototype and a kickstarter.
Also, I'd posted something (not the same exactly) in "supercharger infrastructure" but seems no one there interested to respond. This is after all for the M3 primarily in mind.