Controlling the time when charging commences

[rihallix]

I'm strongly considering leasing a new i3 REX. I live in the Bay Area (California). I get reduced rates after 8pm.

Can I set up my car or the charger to start drawing electricity after 8pm when my electricity rate drops by 50%?

E.g. I get home at 7pm, I plug it all in in the garage, then the car/charger lays dormant until 8pm when it commences charging without requiring any interaction from me.

Or is there a way of initiating it via an app - plugging it into the wall charger, and via the app initiating commencement of charging?

 

[rihallix]

Also is there a particular charger model that works best for the i3 REX - I ideally need the car charged in 10 hours. As mentioned ideally I want the car to avoid drawing charge until after 8pm when electricity prices drop.

Is it better (longer range / longer battery life) to charge at a slower rate?

I want to fully charge the i3 REX between 8pm and 6am (so 10 hours to 100% is fine).

 

[jadnashuanh]

There's a menu option to setup low-cost charging window in iDrive, so yes, you should be able to make that happen. Note, though, that if you plug it in when the battery is very low, it will start to charge the battery up a bit, and then stop until the window. Some of this, I think, is affected by the ambient temperatures. Assuming you have an EVSE that has 32A, it should not take more than about 4.5Hrs with the current, 2017 i3's battery, so your 10-hour window is more than adequate.

The maximum on-board charging capacity (the charger is in the car, it is not the EVSE) is limited to 7400W/hr. Since power = volts * amps, in the USA with typical 240vac inputs, a 32A EVSE will max out the i3. Now, next year, they may include a higher capacity on-board charging circuit, and you won't damage anything except for your budget if you get an EVSE that can handle more than 32A, and with a larger battery, it would just take longer to charge. Some will have to worry about how much power they can dedicate to the EVSE with their current power panel, though. In my case, a 32A unit pretty much was the maximum I could put into my panel.

The car determines the amount of power it wants...the EVSE only announces how much power it has available.

If you want to avoid the menus on the car, there are some EVSE's that you can control via the internet and setup windows and track what's going on. Personally, I don't have access to low-cost power windows, so have not dealt with it, but there are threads around that discuss it. Note that the s/w in the car has gone though numerous tweaks since introduced, so what might have been true early on may or may not still be an issue. I've got a Clipper Creek EVSE that has been working fine. Note, the logic in some can have issues if you have a power outage...they don't always reconnect. Doesn't happen often, but that could prevent you from waking up with a less than full battery charge.

 

[cdnji]

You set the i3 to charge at a certain window to take advantage of discounted rates. However, if the car is in a different location, the schedule will still be followed. You have to disable the feature when you're charging at a different location.

I have a hardwired ChargePoint EVSE at home. It can be set to charge a car only at certain times to take advantage of discounted rates. So when I plug in the i3, the EVSE won't dispense electricity until the cheap rates kick in.

To me, that is a better solution because then, you'll be able to plug in the i3 anywhere and not worry about disabling the schedule.

Charging at a slower rate... If you meant using the supplied Level 1 EVSE vs using a Level 2 EVSE, using a Level 2 EVSE has no adverse effect on the battery life. Using a Level 3 charger on a regular basis, on the other hand, would have an adverse effect on the i3 batteries.

I am neither an i3 nor a battery expert. What I'm sharing below are my personal guidelines.

- Turn on pre-conditioning on the i3.
- If you decided to install a Level 2 EVSE, turn on "automatic climate control". The Level 1 EVSE doesn't deliver enough juice to charge your i3, pre-condition the batteries, and set the internal climate of your i3, all at the same time.
- If you have the option, park and charge your i3 in your garage. If your i3 is parked outside, especially in the cold months, you're wasting electricity pre-conditioning the batteries in an adverse environment.
- Don't cheap out on installing a Level 2 EVSE. Get a licensed electrician to do it. You'll probably need a new circuit installed unless you happen to have a spare 40amp circuit.
- If your EVSE and the circuit breaker it is connected to (must be a dedicated connection, hardwired or not) supports it, and your main breaker supports it, set the i3 to charge using max levels for both Level 1 and Level 2 charging. Only set charging to a lower level if your circuit breaker trips.

 

[rihallix]

Thanks @cdnji. So it's a function of the car, and one doesn't need to pay more for a charger to control when the car draws charge - the car can be set up so it doesn't draw charge until 8pm (off peak).

I'll be charging up at home every night regardless so not worried about the issue dealing with these settings at different charge points.

 

[EVMan]

I am completelyyyy puzzled why i3 forces to set departure time ( and will waste energy heating battery) , when setting low price charging hours.

They are completely unrelated.
What if you do not have a fixed time of departure .......or u do not want to drive on weeked , but want to top up your battery....

 

[jadnashuanh]

You can setup the departure time by the day and there are three separate entries, so you do not need to follow the same schedule on the weekend. Or, you can setup the next day's setting via your phone app, which is what I do because every day is different. There are not enough slots to program each day individually, though. So, you could have one schedule for M-F, and a different one on Saturday and a third for Sunday.

Setting a departure time and a low-cost window has the advantage that charging warms the battery, so if you have a departure time set, it could delay charging so it didn't need (as much) separate battery conditioning to get it to the optimum temperature...IOW, heat the thing twice, once by charging, and second, to get it ready to drive away most efficiently.

 

[EVMan]

Well the issues is , why force to set departure time , for low cost charging.

in fact , the logic should be almost the reverse , if any

like my low cost charging is between 11 PM to 6 AM.
I leave like 9:30 AM


So , when will it pre heat my battery ? Which time. ? My charges increase in day
My compute is only 10 miles. so preheating is a wasting energy.

 

[jadnashuanh]

The most time the battery conditioning will use is about 3.5 hours (it's a max 1Kw heating element, so a max of 3.5Kw but it won't use max all of the time). But, given that they will be warmed during the charging cycle and have a fairly large mass, it may not need much. Preconditioning the cabin needs to occur near the time you're leaving, and typically will run for about 20-minutes. So, you don't need to precondition the cabin, but also consider that properly conditioning the batteries also allows them to achieve a higher energy density faster than they would if cold. In fact, if the batteries are quite cold, the car will try to warm them up a bit before doing major charging. And, if you plug in when they are quite low SOC, it will bump them up a bit before pausing for the window.

There are some EVSEs that can be setup to work off of a timer, so you don't have to use any of the car's capabilities to specify a window. One of those might work out better for you.

I think BMW felt that combining departure time with the window would produce the lowest power use with the longest range and comfort, but yes, it could be more flexible. Lots of variables to juggle.

 

[brastic]

I am also in the Bay Area and have been playing with the i3 set up for charging. First we need to understand how PG&E charges. The off peak is where you want to charge your car at the lowest prices. If you have solar panels, you can charge during solar projection if your array is big enough.

PG&E as of today. (Log into your PG&E account for more details)
Weekdays
Off Peak 11pm - 7am
Park Peak 7am - 2pm
Full Peak 2pm - 9pm
Park Peak 9pm - 11pm

Weekends/Holidays
Full Peak 3pm - 7pm
Off Peak 7pm - 3pm

As for preheating, I use this feature a lot. It is not about heating or cooling the batteries, but getting the cabin ready. I live on a hill, so I do not care about the energy usage to heat or cool the car in the morning. I also have to admit that when I am out and it is hot, I will have the car precool while in the parking lot. I also tend to use the cell phone app to heat/cool the car when I leave work. Not that I need to, it is just nice to have the car ready before I drive.

 

[jadnashuanh]

For maximum range, you want the batteries in their sweet spot for temperature and have the cabin preconditioned without having to drain the battery in the process. The car will not condition the batteries (well, at least warm them) unless you are plugged into your EVSE, but you can precondition whether plugged in or not. In a warm climate, you may not notice any difference, but if it gets cold where you live, setting a departure time is well worth the effort. Otherwise, to just precondition the cabin, it's probably easiest to just use the app, and do that a bit before you're ready to leave. Don't have a smartphone or tablet...it's pretty cheap to buy an off-brand Android tablet with a WiFi connection, even if you only use it at home (or at work, if they'll let you log into their network!) to control the car. No WIFi...you probably wouldn't have bought an i3.