What does a L2 house charger actually do for the ~$500 price, besides provide an appropriate plug? It doesn't change the voltage. The current is controlled by the car and protected by the house circuit breaker. Why can't we just directly plug the car into a NEMA14-50 outlet?
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What does an EV charger actually do?
- Thread starter cstork
- Start date
kingkong5
Member
Since the home charger is hardwired in place, it can charge slightly faster than connecting the mobile charger into a NEMA 14-50, but since you're charging it overnight that difference is probably meaningless. I have a home charger because when I got it (3 years ago) I got it for free when I asked nicely when picking up my Tesla, and also SCE gave me a $500 rebate for the installation, so the whole thing was just about free. If I had to pay for it, I'm not sure I would spend that much over just putting in a NEMA14-50 in the garage. One thing about having a home charger is that it's nice to be able to keep the mobile charger in the car, and not have to unplug it from the wall when going on away trips. Also, it looks cool.
Potentially faster charging as was said. Permanent installation, even outside with rain and snow. Prevents you from forgetting your mobile charger when you leave home (although you could buy a second mobile charger). Safer than using a 14-50 with constant plug/unplug. There's an actual switch in the wall connector that cuts power until the car is verified.
Im not sure I understand your question properly, but....
1. The wall connector isnt $500, its less than that now new
2. The mobile connector does allow one to use a 14-50 outlet
With the above being said, it doesnt seem like thats what you are asking. It seems like you are asking "why isnt there just an extension cord from the car to an outlet, like plugging in a blender on my countertop or something?"
If thats the question, I am not an electrician, but I believe the answer to that is
"because of the amount of power generated, the EV equipment connectors (all types, tesla or otherwise) provide electric and electronic checks and balances to announce to the vehicle how much power there is, ensure there is not excessive heat build up when charging and other safety checks help prevent people from killing themselves / burning their residence down from the improper application of that much power".
The EVSE is a piece of safety equipment that serves a few purposes. First, it checks for ground faults before allowing power to flow to the car. Second, it tells the car how much power it is allowed to draw from the circuit. Third, it isolates power in the event of any electrical faults.
That's what I have for our 2 Tesla for the last 2 years, just use the Mobile Connectors to NEMA 14-50 outlets. We don't take the connectors on trips. We just use superchargers so the MCs are attached to the outlets for the last 4 years. One of them is Gen 1 so it is even charging at 40 Amp. The Gen 2 is charging at 32. It really doesn't matter because either one is fast enough to charge the car overnight.
When we bought our first Tesla, the Tesla advisor told me that we don't need to buy the Wall Connector unless we wants the charging station to look cool. Or if it is installed outside the house.
davewill
Active Member
The locking mechanism of the plug into the car keeps people from unplugging it while charging is happening, which would cause some serious arcing. Also, the NEMA plugs are not made for thousands of plug/unplug cycles (think about public stations) the way that the EV plugs are.
Detects ground faults in the circuit
Detects under voltage and over voltage conditions
When there is a NEMA wall receptacle and a power plug, can detect overheating at the plug
Negotiates the charging session with the vehicle; establishes 120V or 240V charging and the maximum charging amperage for the circuit. Without this negotiation the vehicle would have no way of knowing if the charging circuit could support charging at 48 amps or may be limited to as little as 12 amps. (The vehicle's charging equipment may default to charging at 48A. The EVSE will set the maximum for the charging session, up to the maximum for the circuit.)
A 60A 240V GFCI breaker (required for the NEMA plug installation) will run you $120-250 depending on what kind of panel you have, a high quality 14-50 outlet suitable for regular plugging/unplugging with an enclosure will run you close to another $100. A charging cord may be an additional expense, or nuisance if you forget to bring it with you when you leave the garage. The wall connector runs $400. In all, not enough of a difference to get very excited about. The wall unit is simple and elegant
The circuit breaker must not exceed 50A for the NEMA 14-50 receptacle, power plug application.
As mentioned above, this is a safety issue: the EVSE (the device which sits between the power in your house and your EV) will not allow the charging to start or continue if there is a safety issue with the power connection from your house to the car. There is a handshake with your car and a continuous monitoring of the connection. A good part of the EVSE is a ground fault circuit interrupter which will prevent electric shock if you touch the charging cable while its raining (as an example).
As a side note, the current electrical code requires a GFCI circuit breaker if you have a NEMA 14-50 connector. But no GFCI is needed if you have a direct wired EVSE to your house power. The reason is that the GFCI breaker is to protect for problems in the NEMA 14-50 connector. Since the EVSE has its own GFCI, a direct wired EVSE does not need a GFCI circuit protector.
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I think its already been covered in this thread, but the short answer is :
"because this is a lot of power and can easily kill one or more people if precautions are not taken. Verbal and written precautions are not enough, as humans have proven time and again that some will ignore verbal or written warnings even if said warnings are to safeguard themselves."
TomServo
Active Member
And FTR the “CHARGER” is IN THE CAR. That box with the cord and plug is the EVSE.
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