Oleksiy
Posts: 45
Joined: Fri Mar 23, 2018 4:30 am
Location: Kyiv, Ukraine

Re: True Battery Range

Tue Aug 07, 2018 1:21 pm

GuyD wrote:Sorry to be so clueless (new to an i3) but where is the 'hidden' menu?? Hidden from whom?!

Check here https://bmwi3owner.com/2016/01/secrets/#more-546

jadnashuanh
Posts: 4197
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: True Battery Range

Wed Aug 08, 2018 8:14 pm

ICE cars, at least some of them, have range to empty calculations as well, and they are often wrong, too. The computer does NOT know how you will drive in the future or the weather, so it is an educated guess. You'll find that your estimate is better IF you're running the nav system with a destination in it, as then, the car DOES know your intended route, speed limits, and terrain, so its estimate is more educated.

AFter awhile, you'll get an idea of your typical miles/kwHr, and can estimate your range if you can do a bit of math in your head. Given the moving average the i3 uses, that may be more accurate if your driving is going to be different and/or in different environmental conditions.

Everyone's driving technique is somewhat unique. The computer does a decent job, just like the gas gauge on an ICE about how much is left, but how far you'll get, only you can figure that out. In general, the car's estimate is a bit pessimistic, and you can eke out a few more unless your changing your techniques.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

GuyD
Posts: 21
Joined: Wed Jun 06, 2018 6:06 am

Re: True Battery Range

Thu Aug 09, 2018 7:54 am

OK so we have now completed our own real world range test on our new-ish i3.

Drove 215kms setting off on full charge. Weather pretty cold (for here!) - 8-14deg C; gentle breeze; mostly highway at average 90kph. Bit of up and down but no real hillclimbing.

Rex kicked in at about 208 kms and the i3 ended up home with 10% range left (having been presumably topped up a bit from 6% by the Rex) Did, however, seem to use about 15kms petrol range to do 7-8kms (gentle uphill) and to charge the batteries a little.

This is certainly the longest trip we would do normally from home so that is useful info and relaxes us a bit. The car does seem to get more range with our normal 20+ deg C days.

jadnashuanh
Posts: 4197
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: True Battery Range

Thu Aug 09, 2018 1:43 pm

Speed and temperature are the biggest factors in range available. The drag goes up radically as the speed goes up. Temperature is not as much of an issue if you set a departure time and don't take a lot of intermediate stops where things cool off in between segments. Especially on the REx, heating can be a factor...the BEV has a heat pump that provides most of the heat unless really frigid, then it would become like the REx. The heat pump can provide maybe 3-4W of heat from the use of 1W of energy to run the heat pump. When resistance heating is called for, that drops to 1W of heat from 1W of battery capacity...a major difference. Two reasons the REx isn't as efficient as the BEV: extra weight and no heat pump. You don't get something for nothing.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

GuyD
Posts: 21
Joined: Wed Jun 06, 2018 6:06 am

Re: True Battery Range

Fri Aug 10, 2018 3:09 am

That's very interesting - I did not know that the Rex and Bev have different heating and a heat pump is definitely the way to go.

The South African i3 does not have the facility to pre-heat the car (seldom so cold here - no heated seats or steering wheel either..) but I'm thinking it may marginally increase the range on cold days (less than 12deg C) if I turn on the car and leave it standing for a while still plugged (if this is possible?!)

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