Charging speed for 120h UK i3

[ColinP]

PPPS I phoned the cord supplier. They confirmed that all UK i3s are rated up to 11kw, 16amp, 3-phase. So, in summary, my EVSE should be compatible with the car; it is the single phase cable that BMW supplied that is the problem. Sorry it took me some time to get there!

 

[user 4543]

I'm in the same position, I asked for a 3 phase cable when I bought my 2016 94Ah i3, but the dealer supplied a single phase item.

I'm not too concerned, as I mainly use local Polar CCS 50kW public chargers, and find 22kW devices aren't very common in the UK...

Overnight 3kW home charging is adequate when I need a top-up (and is better for cell balancing) Also good on cold mornings for preconditioning!

Chris.

 

[alohart]

PS (see previous post) I just looked on https://evconnectors.com/ev-plug-bmw-i3-cable They offer 32amp, 3-phase, 22kw cords @ £135-170.

The i3 charging leads chart on that page is misleading in that it lists a 32 A 3-phase 22 kW charging lead while no such charging lead is listed for sale, and no i3 has a 22 kW 3-phase charger. However, a 32 A single-phase lead is listed which might be what you already have and which would offer only 3.7 kW of charging power for an i3 with a 3-phase charger.

Charging protocols can be confusing. However, consider yourself lucky that you have the 3-phase 11 kW charging option unlike us North Americans.

 

[alohart]

Overnight 3kW home charging is adequate when I need a top-up (and is better for cell balancing)

Cell balancing occurs only when the battery pack isn't being charged or discharged, so how could 3 kW home charging be better for cell balancing?

 

[jadnashuanh]

FWIW, having a cable capable of carrying more current than the source can provide only costs in the money to buy it, it will function fine. There is no smarts in the cable, but there is a switch (or two, depending on whether it is tethered or not). The combination of the pilot signal from the EVSE announcing how much current it can provide (this is independent of the cable, but that needs to be matched - the EVSE and vehicle have no way of knowing) and the vehicle's internal charging circuits are what prevent the vehicle from overloading the EVSE.

The car will always utilize the maximum it can based on what is available and its current needs. IOW, a larger EVSE/cable will work just fine. The i3 may be the limiting factor based on what is being sent to it.

 

[ColA]

First thing to say, I am in the UK and have had a 120Ahr i3 for nearly a year. Things in the US are different!
Second thing to say, I suggest you join speakev.com. There is an i3 forum and there are some extremely knowledgable electrical engineers on that forum.

So, the i3 has a built-in 11kW charger. On ac at a public charging station (up to 22 kW, three phase) you cannot get more than 11kW due to the car limitation. On a UK three phase system, 11kW is around 30 amps. BUT if the supply does not have a tethered cable and you use your own cable as supplied or purchased this is more than likely single phase so you will get much less charging current. Rapid (dc) is the only fast way to charge your i3 on public chargers as you will get nearly 40kW.

Turning to your home wall mounted charger. As nearly every home user has only a single phase supply, nearly all wall mounted chargers are 7kW 30 amps which will charge your i3 in 6-7 hours if the battery is completely flat. The charger usually has a tethered cable which is rated for single phase 30 amps.

It sounds like you have a 3 phase supply into your apartment block but, apparently, only have a 16 amp wall box. Since you will almost certainly have a single phase cable then you will only get 3.5kW charging.

I cannot suggest how to proceed because I don’t know whether your wall box can deliver three phase. If it can and you buy a 3 phase cable (around £230 from BMW I think) then you will get a three phase power of root3 x 230 volts x 16 amps = 6.2 kW.

Hope this helps.