behrengi
Posts: 2
Joined: Sat May 15, 2021 5:14 am

Road trip with DC charging - no REx

Sat May 15, 2021 6:49 am

I am planning a 500 km (~310 miles) road trip with my 94ah i3. There are DC charging stations every 100 km except for a 145 km (~90 miles) part. I planned the trip in ABRP with speed adjustment on but otherwise default options. When it lowers the speed to 90 kmh (~55 mph) in that difficult part it predicts that I will safely arrive at a charging station with %11 battery left, and when it lowers the speed to 100 kmh with %5 battery left.

I haven't used ABRP before, so I don't have any ideas about how accurate it is regarding its predictions. I also use my i3 for short trips within the city only and I don't have much experience with speeding with it etc. I noticed that it uses 5.6 km/kWh (3.5 mi/kWh) as a reference consumption, I usually see around 7.2 (4.5), so I am also hoping it underestimates the range rather than overestimating it.

I asked this very same question on Reddit and a user told me fast charging 4 times a day may be detrimental to the battery. I searched here and Reddit for people who had completed a similar trip with only DC charging and I couldn't find any.

What do you say? Is this a safe trip to try (can I complete the 145 km part)?

What about fast charging 4 times a day? Is this something I should avoid at all costs? Is it really different than charging 4 times in let's say in a month or a year? I rarely used fast charging except for the first year I've owned this car.

Note: I bought the car in 2018, drove it for almost 20000 km (~12000 miles). I checked the battery status today and Batt. Kappa. max is 29.6 kWh.

JohnWasser
Posts: 87
Joined: Sat Mar 07, 2020 6:15 pm

Re: Road trip with DC charging - no REx

Sat May 15, 2021 9:47 am

I'd make sure I had data on Level 2 chargers both before and after the target DCFC. As you get closer, the amount of the remaining charge will become more definite. If the car says that you won't make it, just spend an hour at a Level 2 charger on the way. Maybe you can line up one with a place to dine and/or shop.

If you get to the target charger with 6% (6 miles?) left, it would be nice to know that you can get to a working Level 2 charger if the target charger is dead.

websterize
Posts: 531
Joined: Sun Sep 07, 2014 3:39 pm
Location: Maryland, USA

Re: Road trip with DC charging - no REx

Sat May 15, 2021 3:52 pm

behrengi wrote:
Sat May 15, 2021 6:49 am
... What do you say? Is this a safe trip to try (can I complete the 145 km part)?

What about fast charging 4 times a day? Is this something I should avoid at all costs? Is it really different than charging 4 times in let's say in a month or a year? I rarely used fast charging except for the first year I've owned this car.

Note: I bought the car in 2018, drove it for almost 20000 km (~12000 miles). I checked the battery status today and Batt. Kappa. max is 29.6 kWh.
I’m in a 2018 94Ah BEV and have driven it on two summer road trips (350 miles each way), with three DC charging stops in between. The greatest distance is between home and the first DC charger 102 miles away. I keep speed around 100 kph (62mph) for this leg.

With the car’s automatic heating and cooling of the high-voltage pack, I’m not concerned about the trips degrading its service life. I charge at 50KW stations less than 10 times a year. For the remaining 95% of annual charges, I plug into a 30A, L2 EVSE in an unconditioned garage. The “Batt. Kappa max.” is about ~29 kWh after 30,000 miles in the 2018, my third i3. I’ve driven about 100,000 commuter miles in the three, mostly on highways. I leased the first two and, after receiving a discounted buyout offer from BMWFS on the third, I purchased the Sport.

Note that the i3’s battery management system might have played a role in our trip last summer. By the third DC charge, when the ambient air temperature was hot (mid-90°F), and the highway driving required high power, something in the car throttled the DC charging rate in half, to about ~25 kW. Initially, I thought the issue was the charger, but a representative from Electrify America said, by phone, that all was in order with the station from their end. Driving at high speed all day creates considerable heat, and consecutive DC charges also generate heat, compounding the gain. Slowing the rate of charge might have been a safeguard. Add hot ambient temperature, and it was time for another cold beverage at the nearby convenience store. As Bjørn Nyland says, when it comes to charging, remember: ABC (Always Blame Car).

Our next i3 road trip is in early July. There is a 15A, L2 at our destination. As soon as the kids and I arrive, we plug in (Always Be Charging), and the car goes into overdrive to cool its jets. If you end up taking the EV pill, enjoy the adventure.
2018 i3 Sport BEV | Coding spreadsheet

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