75 amp charging

[35mphgolf]

It looks like my time to finally get an i3 may be fast approaching. From the research I've done it seems like the Juicebox Pro 40 is a solid choice for a home charger.

I checked the company's website again and noticed they have a 75 amp charger now! Anybody have any experience with this? Any detriment to the batteries at this level (long-term or near-term)?

 

[I33t]

No detriment, but the i3 will only charge at 30/32A.

Might be worth getting for future vehicles if your electricity supply is up to it.

 

[jadnashuanh]

Regardless of the available amperage, an EV will only use what it was designed for, and in the case of the i3, 7400W, or around 30-32A with 240vac inputs. Just like you can plug a 10W bulb into a 15A circuit without issues, the same applies to an EV. Keep in mind, though, that it is unlikely that you have enough spare capacity in your electrical panel to put in a 70A device. To do that, using the 80% rule, you'd need 87.5A, and since you can't get a breaker that size, probably 90 or maybe even 100A. Not counting the substantial cost for the wiring that can handle that amount of current!

Buying one with a larger capacity than the i3 can currently use may not be a bad choice IF you can support it without upgrades to your panel, but it may be awhile before any car you're likely to buy could make use of it. About the only one out there now is maybe a Tesla.

 

[35mphgolf]

Got it - makes sense. Wasn't sure what the i3's amperage charge rating was.

And if it's just 30amps - what about those 40amp chargers like the Juicebox? Does the car just draw the max current it can support regardless of the capability of the charge unit?

 

[sunny]

Got it - makes sense. Wasn't sure what the i3's amperage charge rating was.

And if it's just 30amps - what about those 40amp chargers like the Juicebox? Does the car just draw the max current it can support regardless of the capability of the charge unit?

I am installing the juicebox 40. My box can handle the amperage, and it is portable if i move. the reason to get a 40 amp is to future proof your purchase (since it's fairly expensive). I have read 40 amps will buy you 10 to 15 years....

 

[jadnashuanh]

The EVSE has a control line that can be read by the EV that indicates how much current it can provide (called the pilot signal). Knowing that, the EV will use up to that amount, or whatever its maximum needs are. FWIW, if you use a 40A device, to meet the 80% rule, it must be on a 50A circuit. The wire is not inexpensive, and could be a major factor in the install cost depending on how far it must be run, not counting what's available at your panel, and the possible need to upgrade that.

FWIW, the charging circuits are IN the car...an EVSE is a smart on/off switch. Now, a CCS (DC fast charging unit) outputs a high voltage DC voltage (a monster variable DC power supply), and is lots more expensive and complex.

 

[louisgrenier]

FWIW, the charging circuits are IN the car...an EVSE is a smart on/off switch. .

I am slowly getting it. How do some EVSE limit the power ? Like the Turbocord 110-240 that is limited to 3.8 kw on 240. Or some units that have a button to choose levels of power. They do communicate with the car to limit it's on board charging to lower levels ? Like if i have my 240 v EVSE that is rated to 6.8 kw, and i want to use it on a circuit that does only support 5 Kw, i go in the menu of the car and choose a lower level 2 charge. But if i use a 3.8 Turbocord, it will communicate with the i3 to lower the charging power without having to go to the i3 menu ?

Thanks

Louis

 

[I33t]

But if i use a 3.8 Turbocord, it will communicate with the i3 to lower the charging power without having to go to the i3 menu ?

Thanks

Louis

The Turbocord tells the i3 that it has a capability of 3.8kW, and the i3 knows that it is within it's max charging parameters so it tells the Turbocord it will take the whole 3.8kW.

http://electronicdesign.com/power/understanding-us-and-european-standards-electric-vehicle-charging

 

[35mphgolf]

http://electronicdesign.com/power/understanding-us-and-european-standards-electric-vehicle-charging

Good information - much thanks.

 

[jadnashuanh]

All EVSE's send a pilot signal to the vehicle that announces how much power they can provide. It is then up to the vehicle's smarts to never exceed that available power.

IN the i3, when using level 1 (120vac), you can tell the car to limit its maximum power draw, for example if you have the EVSE plugged into a shared circuit, and pulling it's maximum might cause the CB to trip (maybe it's on the garage circuit, and then someone uses the door opener).

Some EVSE's can be adjusted to announce they have less power than their design, and on some of them, it's automatic based on what adapter you plug in.

 

[jadnashuanh]

FWIW, think about it like this...you may have a 15A circuit that you plug your phone charger into the wall...the charger doesn't care that there's 15A available. In the case of an EVSE, while it's basically an on/off switch, it and the vehicle has the smarts to announce how much is available, then the vehicle limits how much it wants without exceeding what's available. It's not all that hard to adjust the pilot signal with software IF the board is designed for it. That could be automatic, or via switches, or a variable resistor into a voltage controlled oscillator (some way for the logic board to respond to what you're trying to do). On the car's end, it really doesn't care. Most EVSE's are pretty dumb, but some have more smarts to them - doesn't change the basic operation, though.

 

[michaelbmw]

The term that some people use is that the EVSE "advertises" the maximum current it can supply. The car takes whatever it wants, up to that advertised maximum.