Maximum charge rate?

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George1000

Member
Joined
Jul 12, 2021
Messages
7
Any idea what the maximum charge rate is for a 2020 i3? Some rapid chargers are available upto 300kw apparently.
 
50 kW.

There's some solace that our batteries are 1/3 to 1/2 the size of other cars, so at least the charge times are comeasurate.
 
So there is no advantage in using the 60/120/300kw chargers? What is the technical reason it can’t charge at a higher rate than 50kw? To prevent the battery from being cooked?

Is there a certain percentage where the car slows down the charge rate? Thought it was supposed to be 80 per cent, but watching the percentage go up on a rapid charge it doesn’t really seem to be any slower even at 90 plus per cent.
 
Nope, no advantage to using the higher rate chargers.

I don't know why it never was increased, but I suspect it originally partly had to do with how small the i3 battery was when it launched in 2014, and 50 kW was deemed plenty. In fact, DC fast charging was an option in the first year, which sounds ridiculous today, but maybe BMW was thinking not many people are traveling outside of a tight home-work-errands circle, and 7.7 kW of Level 2 overnight home charging would be perfectly adequate.

On my recent DC fast charges, not that I was paying super close attention, but I'd see 35 kW and tapering down in the low 90% range, and it was that last 4 or 5% where I'd peep a 3 or 4 kW rate as I tried to reach 100%.
 
I've found there is a benefit in using a charger beyond the 50kW the i3 can accept: many 50kW units simply can't deliver full output, even when the car's capable of accepting the power.

So when I actually need a really fast charge, I head for my local BP Pulse 175kW CCS facilities. (2 devices, plus 24h shop and café) Although it costs a bit more per kWh, it normally delivers the full 50kW that I'd expect!

Chris
 
George1000 said:
So there is no advantage in using the 60/120/300kw chargers? What is the technical reason it can’t charge at a higher rate than 50kw? To prevent the battery from being cooked?

Is there a certain percentage where the car slows down the charge rate? Thought it was supposed to be 80 per cent, but watching the percentage go up on a rapid charge it doesn’t really seem to be any slower even at 90 plus per cent.

80% is the average first taper on most cars, so you'll see that as the normal advice regarding unplugging and moving down the road. Electrify America even sends a notification to advise drivers they could be paying a whole lot for the same speeds they get at home.

Some cars taper much sooner than 80%, like the Bolt and the Kona and a few don't aggressively taper until later in the pack. The i3 holds great speeds well into the 90% region. I've seen as high as 40kW at late at 95% on a nice warm pack in mild ambient temps where the car doesn't have to cool the battery too aggressively. So while the i3 on paper doesn't compete with the new cars. In the real world it's very competent at the fast charger.
 
With such small battery packs (compared to Tesla) our little city dwelling grocery getters can’t handle heavy kW. Time will tell what the right combo or kW charge rate and battery pack size is the best combo. BMW engineering most likely did long term testing on quicker DC charging and realized it created quicker degradation.
 
George1000 said:
So there is no advantage in using the 60/120/300kw chargers? What is the technical reason it can’t charge at a higher rate than 50kw? To prevent the battery from being cooked?

Is there a certain percentage where the car slows down the charge rate? Thought it was supposed to be 80 per cent, but watching the percentage go up on a rapid charge it doesn’t really seem to be any slower even at 90 plus per cent.

Unless you are constantly on the road, you'll find public DC charging a rare and needless worry.
 
Speculating, particularly because DCFC was an optional item at launch, 50kW was in keeping with the technology in 2013 and was sufficient for the 22 kWh battery.

As the battery size increased to 33 then 42 kWh, 50 kW remained sufficient, but more importantly, it didn't appear BMW had any interest in investing further in this platform. A higher rate charging capacity may have resulted in more rework than fit the budget.

Keep in mind this car has outlived its expected life. BMW planned to have its replacement, the i5, on the road in 2018. They announced end of i3 production in 2019 only to step back later in the year. It's hard to invest in a platform on the chopping block.
 
Even the new Chevy Bolt can't charge faster than 50kW right now either and other than that (and the current battery recall issue) they could be viable road trip cars for many typical situations.
https://cleantechnica.com/2021/02/16/why-dont-the-2022-chevrolet-bolt-ev-euv-charge-faster/

Finding a non-Tesla DC Fast charger is hard enough at 50kW but finding one that have the fast speeds carmakers are advertising would be even harder! Especially on something like the i3 which is not meant to be a cross-country driver it just doesn't make sense to spend development dollars on faster charging.
 
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