eNate
Posts: 456
Joined: Mon Sep 09, 2019 5:33 pm

Re: Level 1 Living at 16 Amps

Thu Jan 09, 2020 2:00 pm

The EVSE can't determine the amps available.

An EVSE is built for a specific amperage draw, and must be wired per electrical code to support that current. I could buy a 30A EVSE and wire it on to a 15A circuit, and it would never "know." It can't tell the difference between a 15A circuit and a 50A circuit. The car would be told by the EVSE that 30A are available, the car would pull 30A, and the 15A breaker would immediately trip.

This is the same with any other electrical appliance. They draw what they draw. Most household appliances are deigned to work within the limits of 15A. All consumer space heaters max out at the same wattage because of the 12A continuous draw limit on a 15A circuit. Electrical water heaters are sold in a variety of amperages and will specify what gauge wire and what capacity breaker are necessary for compliant installation. 20A industrial tools will come with the funny sideways plug so they can only be plugged into 20A receptacles.

This is why all EVSEs include the disclaimer "must be installed by a licensed electrician." Once wired up correctly, the EVSE eliminates most possibilities for error. Clipper Creek won't even sell their 16A EVSE with a plug ("hardwire only"), probably to reduce their liability for someone plugging it in to an underrated circuit.
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Fisher99
Posts: 314
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Re: Level 1 Living at 16 Amps

Thu Jan 09, 2020 3:25 pm

I'm talking about plug-in EVSE's like my TurboCord. Other vendors, including Clipper Creek, make and sell plug-in EVSE's. The EVSE sits inline, between the wall outlet and the charger. I'm just not understanding why it has to sit external to the vehicle, rather than internal to the vehicle. It would provide exactly the same function and work in exactly the same way. How does the location (external to the vehicle or integral with the vehicle) change anything?

You seem way more intelligent regarding chargers, EVSE's, and things electrical in general, so I have to assume that my electrical incompetence is preventing me from grasping some basic facts here.
2014 BMW i3 with Range Extender Engine, Capparis White/Frozen Black, 20" wheels,, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, TurboCord EVSE

eNate
Posts: 456
Joined: Mon Sep 09, 2019 5:33 pm

Re: Level 1 Living at 16 Amps

Thu Jan 09, 2020 4:35 pm

I think I'm understanding your point.

To do it the way you suggest -- internal, dual-voltage, auto-detecting -- is of course possible. I think Chevy or Toyota did this, where you could just plug in an extension cord.

But there remains the need to identify the available current. If we're talking a miserly 12A, that would be it -- the owner would be stuck at that slow rate of charge, even if 30A were available.

Of course, you could get around this by including a selector switch or a settings menu where the owner could select the amperage rating of the circuit being used. But this does introduce the likelihood of user error, tripped breakers, damaged receptacles, and fires.

The other route would be to have the internal 12A EVSE, but allow it to be bypassed for an external EVSE for charging points with higher outputs.

And the manufacturer would at the very least have to provide the correct adapter for the electrical connection to work with whatever standard is in place where the car is being sold.

None of that is impossible. But my guess is the manufacturers expect that the majority of their buyers aren't going to tolerate charging at 12A, and find it more economical / practical / simple to include the "OUC" EVSE as a port add-on accessory that gets popped in the frunk and never sees the light of day.
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jadnashuanh
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Re: Level 1 Living at 16 Amps

Thu Jan 09, 2020 6:56 pm

The external EVSE is a semi-smart power switch. All of the real smarts and the ACV to DCV conversion is done in the car. The EVSE announces to the vehicle how much current it has. It does not say how much voltage. The car, as long as you don't provide power outside of what it can handle, doesn't really care. The EVSE sends a signal that says - I can provide up to X amps. The car then dutifully never tries to draw more current than the source says it has. Amps*Volts=POWER. So, the higher the voltage OR amps will provide more power.

You can think of the car as a big power user that can adjust so that it doesn't pull more power than what is actually available. The EVSE tells it, and does some interlock safety stuff, but basically is just a smart power switch.

It's possible for an EVSE to sense the power available and potentially say it has more amps, but it would require an adapter based on the plug attached to it. In the USA, a plug with the standard 15A configuration will fit into a 15 or 20A receptacle, and it has no easy way to tell whether it's plugged into a 15A or 20A one. If it has the 20A plug, it assumes things were wired properly, and it's in a 20A receptacle. Doing this manually with a switch is dangerous, as you could have it set for a 20A circuit, and plug it into a 15A one (assuming it had the 15A plug), and you'd overload the source. So, there's no way for the EVSE to really know what it's plugged into.

Those that are 120/240 v compatible (that requires an internal multivoltage power supply), so that it can generate and process the right interlock signals, not to handle more current. There's more power on a 240vac device at the same amperage...remember, power=volts*amps, so if you double the voltage, you'll get double the power, but the amps stays the same. The only way the car will try to draw more amps, is if the EVSE announces it has more.

Some EVSEs can be internally adjusted to announce they have more, but you must be fastidious to ensure the wiring can handle how you're setting it.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV
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Fisher99
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Re: Level 1 Living at 16 Amps

Thu Jan 09, 2020 11:41 pm

You guys are getting way beyond my pay grade. It's all interesting, but I don't see how it is actually relevant to my point which is simply that whatever a plug-in external EVSE does, it should be able to do if it was built into the car rather than sitting outside of the car. I can see no reason that the physical location of the EVSE should change how it operates.
2014 BMW i3 with Range Extender Engine, Capparis White/Frozen Black, 20" wheels,, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, TurboCord EVSE

alohart
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Re: Level 1 Living at 16 Amps

Fri Jan 10, 2020 12:23 am

Fisher99 wrote:
Thu Jan 09, 2020 11:41 pm
It's all interesting, but I don't see how it is actually relevant to my point which is simply that whatever a plug-in external EVSE does, it should be able to do if it was built into the car rather than sitting outside of the car. I can see no reason that the physical location of the EVSE should change how it operates.
The design of an EVSE that protects its user from electrocution would not apply if the EVSE were internal to an EV. If an EVSE were internal, the user would have to plug one end of a power cable into the EV and the other end into an electrical outlet. If plugged into an electrical outlet first, the cable would be hot when plugging it into the EV. In rainy weather, deadly electrocution by up to 240 V could occur. Smarts in an EVSE prevents this from occurring because the end that plugs into the EV can't be hot until the handshake between the EVSE and EV completes which can't occur until the plug has been plugged into the charging port.

Even plugging into the EV first could result in potentially dangerous electrical arcing when the other end of the cable is plugged into the outlet.

Also, repeated plugging/unplugging of 120 V or 240 V outlets can lead to worn or loose contacts in the outlet resulting in higher electrical resistance and potentially dangerous heat generation.

An EVSE is external to an EV for several very good reasons.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

Fisher99
Posts: 314
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Re: Level 1 Living at 16 Amps

Fri Jan 10, 2020 11:01 am

alohart wrote:
Fri Jan 10, 2020 12:23 am
Fisher99 wrote:
Thu Jan 09, 2020 11:41 pm
It's all interesting, but I don't see how it is actually relevant to my point which is simply that whatever a plug-in external EVSE does, it should be able to do if it was built into the car rather than sitting outside of the car. I can see no reason that the physical location of the EVSE should change how it operates.
The design of an EVSE that protects its user from electrocution would not apply if the EVSE were internal to an EV. If an EVSE were internal, the user would have to plug one end of a power cable into the EV and the other end into an electrical outlet. If plugged into an electrical outlet first, the cable would be hot when plugging it into the EV. In rainy weather, deadly electrocution by up to 240 V could occur. Smarts in an EVSE prevents this from occurring because the end that plugs into the EV can't be hot until the handshake between the EVSE and EV completes which can't occur until the plug has been plugged into the charging port.

Even plugging into the EV first could result in potentially dangerous electrical arcing when the other end of the cable is plugged into the outlet.

Also, repeated plugging/unplugging of 120 V or 240 V outlets can lead to worn or loose contacts in the outlet resulting in higher electrical resistance and potentially dangerous heat generation.

An EVSE is external to an EV for several very good reasons.
Ok! That actually makes sense! Three cheers for external EVSE's! :D
2014 BMW i3 with Range Extender Engine, Capparis White/Frozen Black, 20" wheels,, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, TurboCord EVSE

eNate
Posts: 456
Joined: Mon Sep 09, 2019 5:33 pm

Re: Level 1 Living at 16 Amps

Mon Jan 20, 2020 8:11 pm

Oops, downside to the 16A EVSE.

On Friday I got lazy at home and plugged in to my (nearer) 15A receptacle -- I didn't need the boosted current because I was going to hit 100% at work later that afternoon -- so I set the i3's charge rate to "Reduced" so as not to blow my 15A breaker.

Well I forgot to reset my charge rate to "Maximum" and have been charging at essentially 12A for the past three days. I left work Friday at 100%, as planned, but shorted myself about 10% on Saturday and Sunday's charging sessions.

So today I left home with 35%. I had to drive my father in law 20 miles one direction before doubling back to go in to work, and I was right on the cusp of having enough SOC. So the two of us detoured to an EVGo and I dropped an extra 10% into the battery. While sitting there chatting, I noticed my error -- that the 120v charge rate remained set as "Reduced."

I rolled into my work parking lot with 12% in the battery. I think I would have been at 3 or 4% if I hadn't stopped to charge, which is cutting it a little too close. But I have new confidence in the i3's guess-o-meter as that's roughly what I would have expected based on what it indicated when I began this drive.

This was my first EVGo visit in awhile, confirming that the 16A EVSE is continuing to have a dramatic benefit vs. the stock 12A unit.
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Obioban
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Re: Level 1 Living at 16 Amps

Tue Jan 21, 2020 6:50 am

Ha, I'll routinely get home with <5%... as I generally drive as fast as I can while leaving a ~5 mile buffer to home, in case something goes unexpected.

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