Fisher99 wrote: ↑
Fri May 17, 2019 12:18 pm
I just downloaded the i3 manual, to get familiar with the car before I make the trip to bring it home. It talks about having to have an electrician check the electrical outlet before I use it and then I have to manually set the charging rate on the iDrive system in the car depending on the "current strength" of the outlet? This seems cumbersome to me. What if I'm away from home and want to plug into an available 120v outlet? Is it really problematic to leave it configured to "maximum"?
Understanding how all EV charging in North America works might make all of this easier to understand. Some things differ in other markets.
All EV's can be charged with AC power. Due to the unfortunate U.S. decision to install both 240 V and 120 V outlets in residences instead of all outlets being 240 V, two AC charging protocols have been defined: AC Level 1 (120 V) and AC Level 2 (208 - 240 V). Fortunately, the charging port and plugs for both AC Levels 1 and 2 are identical (described in the SAE J1772 standard). The charger in every North American EV is able to be charged with all AC Level 1 and 2 input voltages.
The device used to charge an EV is called Electric Vehicle Supply Equipment (EVSE). EVSE minimizes electrocution risk, negotiates with an EV's on-board charger to deliver the maximum power both support, and limits the charging power to protect the charging circuit. This is why an EV cannot be plugged directly into an electrical outlet using only an electrical cable. An AC Level 2 EVSE usually has a setting that limits the current that it can deliver to protect the charging circuit. However, an AC Level 1 EVSE usually does not.
An i3 allows the maximum charging current to be set in iDrive for both AC Levels 1 and 2. This setting has precedence over any EVSE current limit setting. Because most AC Level 2 EVSE's have a current limit setting, it's generally safe to set the AC Level 2 charging power to "Maximum".
120 V residential circuits usually aren't dedicated to a single use (i.e., a 120 V residential circuit can usually be shared by more than one 120 V load). So even if the 12 A AC Level 1 EVSE included with your i3 wouldn't trip the 20 A circuit breaker itself, other loads on the circuit could increase the total circuit current enough to trip its breaker. If this is the situation with your 120 V charging circuit, you might need to reduce the charging power in iDrive to "Reduced" (9 A) or "Low" (6 A) which would significantly increase the charging time.
The recommendation that an electrician check the 120 V outlet you'll use for EV charging is because many outlets are old, could be corroded internally, could have loose internal wiring connections, etc. Any of these conditions could cause the outlet to generate enough heat to damage the outlet and/or EVSE plug or to cause a fire. For continuous use such as EV charging, the maximum safe current is 80% of the rated current capacity for the circuit component rated for the least current. Even though modern residential circuits are typically rated at 20 A, their outlets are usually rated at only 15 A. 80% of 15 A is 12 A, the maximum continuous current delivered by that outlet. This happens to be the maximum current of your EVSE, so your EVSE is drawing the maximum continuous current that would be safe for a new 15 A outlet.
BMW recommends against using a 120 V extension cord with its EVSE because this adds another set of plugs and outlets that could generate dangerous heat if they're not in perfect condition even if the cord itself is rated for more than 12 A of continuous current. Many EV owners use 120 V extension cords without problems, but the plugs and outlets should be monitored to ensure that they're not getting hot.
The J1772 extension cable that you referenced on Amazon would be a safer way to extend the reach of your i3's EVSE. However, the JLONG
is almost certainly safer than those made in China like the one you referenced because, unlike Chinese J1772 extension cables, the JLONG includes all J1772 safety features. Unlike what others have stated, any J1772 extension cable could extend either AC Level 1 or AC Level 2 EVSE's, so it could also be used at an AC Level 2 public charging station as well as at home. However, at ~$200, it might be a theft target at a public charging station. Also, its cost could be applied to the installation of an AC Level 2 EVSE, many of which have cables that might be long enough to reach your i3 without a J1772 extension cable.
All North American i3's include the second on-board charger that increases the maximum charging power to ~7.2 kW (240 V @ 30 A).
A dryer outlet is 240 V which won't work with your 120 V only i3 EVSE. However, an AC Level 2 EVSE with a compatible 240 V plug or plug adapter could be plugged into your dryer outlet. Your dryer outlet is likely on a 30 A circuit which would mean a maximum charging current of 80% x 30 A = 24 A. Even though that's less than the maximum current that your i3's charger can accept, its 240 V x 24 A = 5.8 kW charging power is more than twice as much as your 120 V x 12 A = 2.4 kW i3 EVSE, so your total charging time would be cut in half.
If your 2014 i3 has the DC fast charging option (not all did), it could also be charged using DC power from either a DC Level 1 (up to 80 A or 36 kW) or DC Level 2 (81 - 200 A or up to 90 kW) charger. The charging port would have 2 additional pins below the AC charging pins. An i3 can be charged at up to 50 kW of DC power delivered by either DC charger type without any driver configuration (just plug it in). Some erroneously refer to DC fast charging as "Level 3" charging which doesn't exist.