ColinP
Posts: 10
Joined: Sat Oct 26, 2019 2:16 am

BMW i3 charging - recap

Wed Nov 06, 2019 9:03 am

I have trawled through past posts & assembled the following info on my EV; would the ‘experts’ please check my understanding of the facts & proposed action:

My wall box (EVSE) has a capability of single- & 3-phase, 11kW, 16A, 240v; this equates to 3.6kW single-phase or 11kW 3-phase

My charge cable is rated as single-phase, 32A, 250v

My 2019 UK BMW i3 120ah is rated as fast & rapid charge, multi-phase, AC & DC; this equates to a maximum charge of 11kW 16A AC or 50kW DC; the EV is set to maximum charge & the battery is rated as 42.2kWh (96 x 120Ah x 3,667v)

It takes up to 12 hours to fully charge the EV from near empty @ 3.6kW single-phase

How to make my home charging faster?
(1) buy a 3-phase cable (cost £140); this will reduce the charge time to 10 hours, ie limited by 16A output of EVSE
(2) ask EVSE supplier to upgrade the system to 32A, reducing the charge time to 5 hours with 3-phase cable (most suppliers offer 32A at no extra cost to 16A option)
(3) anything else please?

I charged recently at a GeniePoint public charger rated at 50kW DC with CHAdeMO plug but only achieved 26kWh in 42mins, ie <40% charge to full. Is this the fastest I’ll get from a public charger? The ‘Living with BMW’ website says that I should get an 80% charge in 25mins from a 60AH DC 125A 50kW (400-480v) charger.

All advice will be appreciated.

alohart
Posts: 1852
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: BMW i3 charging - recap

Wed Nov 06, 2019 5:45 pm

ColinP wrote:
Wed Nov 06, 2019 9:03 am
How to make my home charging faster?
(1) buy a 3-phase cable (cost £140); this will reduce the charge time to 10 hours, ie limited by 16A output of EVSE
Certainly this can't be correct. Assuming no charge power tapering when nearing full, 40 kWh of usable battery pack capacity, and 90% charge efficiency, charging from empty to full should take approximately 40 kWh / 11 kW / 0.9 = 4 hours. European owners of i3's with 3-phase chargers should be able to provide a more exact estimate.
ColinP wrote:
Wed Nov 06, 2019 9:03 am
(2) ask EVSE supplier to upgrade the system to 32A, reducing the charge time to 5 hours with 3-phase cable (most suppliers offer 32A at no extra cost to 16A option)
The on-board charger is limited to 16 A per phase, so upgrading your charging circuit to 32 A per phase would be a waste of money with no charging time reduction.
ColinP wrote:
Wed Nov 06, 2019 9:03 am
I charged recently at a GeniePoint public charger rated at 50kW DC with CHAdeMO plug but only achieved 26kWh in 42mins, ie <40% charge to full. Is this the fastest I’ll get from a public charger? The ‘Living with BMW’ website says that I should get an 80% charge in 25mins from a 60AH DC 125A 50kW (400-480v) charger.
Your average charging power was 26 kWh x 60 min/h / 42 min = 37 kW. A 50 kW DC charger has a maximum current limit that results in less than 50 kW of charging power over most of a battery pack's charge level range, so the 37 kW average charging power that you experienced seems reasonable. Had you instead charged from ~20% to ~80%, the average charging power should have been a bit higher due to charge power tapering that begins at ~60% charge level. I don't recall any report of any i3 charging at higher than ~45 kW, and that was over a very narrow charge level range.

Also, no non-Japanese i3 implements the CHAdeMO charging protocol. Non-Japanese i3's implement the CCS charging protocol which has a very different and incompatible plug from CHAdeMO. Many DC fast chargers have both CHAdeMO and CCS plugs.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

jadnashuanh
Posts: 4766
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: BMW i3 charging - recap

Wed Nov 06, 2019 8:20 pm

Was someone else also using that charger? If so, it's possible that it's 50Kw total, but now divided by two. Also, they usually have some thermal protection, and if things get hot, it will lower the power available.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

Return to “News and Main BMW i3 Forum Discussions”