Faster driving question

[maestroman]

Prospective i3 owner here, new to this forum.

Driving at 75 mph how many miles will a non-REX i3 last before it requires charge please?

I am considering the purchase of the 94 version for daily 83 kilometre (52 miles) round trip. Some of this journey is city traffic and some motorway.

Thank you.

 

[Tooks]

I'm a fairly new i3 Rex owner, and brand new here!

My daily round trip commute is similar, being about 50 miles of A road including a 10 mile stretch of Motorway. I don't drive slowly, and cruise at about 75mph on the motorway part. Mine is the 60Ah version, and I usually arrive home with anywhere between 25 and 40% left in the battery, dependent on if I popped out to the local service station for a sandwich at lunch or not, and what sort of speed either side of the motorway I've averaged. 50-55 on the A and B roads is about right though, on average.

The caveat is, this is during the summer with high ambient temps. In the winter I expect it will be a much closer call, and realistic range on mine with a full battery in 0-5c will likely be 60 miles.

If you're buying the 94Ah version though, I expect you'll breeze it any time of the year and with any load on the vehicle.

I've downloaded the free Apple Book 'Electric Vehicles and the BMW i3' by David Bricknell and there are a couple of graphs in there that show energy consumption of 60Ah/94Ah versions at various speeds and temperatures. It seems to suggest around 55-60 for the 60Ah and approx 90-95 for the 94Ah. That's summer though, it will drop in the winter. That's also assuming a theoretical 75mph all the time with no changes in elevation or head or tail winds though. In reality, you'll be stopping and starting either side of a motorway stint which will extend range significantly, as will backing off to 70mph instead of 75. The 94Ah version seems to be happier at prolonged high speed than the 60Ah version too, all to do with discharge rates of the different sized packs.

I'm averaging 4.2 miles per kWh, which multiplied by 18.8kwh (my 60Ah cars available power) equals a theoretical 78 miles. That is in summer though don't forget. If I had the 94Ah version, I'd probably be looking at a practical range of 110-115 at the same consumption?

Sorry to go on, but it sounds like this deliberation is something that everybody has when they first ask themselves the question 'would a BMW i3 work for me'!

I needed another option for occasional longer trips, but didn't fancy another car, so hence the Rex, but it's usually silent in the back as I see it as a backup.

 

[maestroman]

My apologies I should have said 130 kilometre (80 miles) round trip.

Thank you for your informative post Tooks.

 

[janner]

No problem with 94 Summer or Winter. Ok with 60 if you drive slowly.

 

[rtanov]

I have gone trough 2 cold winters already and if I drive in comfort and above 70 mph I've seen the range go down to 50-55 miles. This said, you can easily form a pattern that would give you enough comfort and speed and consistent range to go more than 55 miles (unless you forget to charge or precondition ). My wife works 50 miles away and drives the BEV, but can reliably charge at work, and she has not had a single instance during the 18 months she has the car to be stuck at work and not be able to drive home. If you are looking at the 2017 model then you can pump up my numbers by 50%.

 

[jadnashuanh]

Driving one longer trip verses lots of short hops makes a difference if you're going to have the HVAC system condition the cabin comfortably in summer or winter. I don't know if the heat pump is standard on the BEV in the UK, but it is in the USA, and that can really help when it comes to heating in milder climates, otherwise, one watt out of the battery gets you one watt of heating verses 3-4W with the heat pump. Preconditioning both the batteries and cabin before you leave while on mains power can also make a big difference. The worst range would be lots of short trips when you are running in comfort mode where it has to condition the cabin a lot each time...watts that aren't moving you. Keeping it at temp isn't as bad. FWIW, BMW has said that above 35mph, it's more efficient to have the windows closed and use the HVAC verses the extra drag caused by having the windows open and it off.

On the USA range test (probably more realistic than the EU cycle), they're claiming 114m/charge with the 94ah battery pack.

 

[mrsmith]

I do an 86 mile round trip commute from near Swindon to Bath centre every day. 9 miles each end on fast A-roads and the big bit in the middle on M4 motorway. I have a 2014 BEV i3 with the heat pump.

Right now in the summer, if I stick to 65mph on motorway bit, I can 'just about' use 50% of battery each way, however I always charge at work on a three pin socket.
75-85mph on the motorway bits means I use about 60-75% of battery.

In the winter with pre-con I would use 60-75% of battery at 65mph and 80-95% at 75-85mph!
It's all about how fast you go on the motorway. If I nail it (top speed of an i3 is 95mph) I can roll into my driveway with 1% of battery left no problem!

A new 2016 i3 with bigger battery could do the round trip without a charge at your destination no problem.

 

[maestroman]

I can elaborate that of my 80 mile round trip, 60 miles (75%) of it is motorway and I like to drive 75 miles per hour (120km) on it. Thank you for any further advice.

 

[Ki3]

Maestroman did u put in an order then? I have a similar situation to yours. 75 mile commute, 65 mile motorway, 5 mile on either end local A roads in the uk around 40-50 mph. Need to understand how the 94ah rex will stand up - can i realistically get whole trip done on electric only (no charging available at work)?