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I am concerned. I have owned my i3 for 8 months & when I charge it the estimated maximum range has dropped from about 80 miles to about 60 miles. These seem to be real world - as opposed to computer predicted ranges as I could get 80+ miles before the REX cut in going cross country & now it's clearly less. I just wondered if anyone has had a similar apparent drop in battery performance, because at this rate I will be pushing for a battery replacement under guarantee within a year. Which is worrying.

Geoff
 

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It's very unlikely that you are experiencing actual battery degradation - at this time of year it's mostly down to the temperature and use of resistive heating in the Rex version.

Out of interest, do you have the winter pack with battery pre-conditioning?
 

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I am also getting similar figures, its temperature related - yesterday was via mild and my range this morning on the GOM was closer to 70 than the day before.
 

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It will be the Weather. It is very noticeable in the Twizy as the battery has little protection form the cold. As this is my 3rd Winter then I expect the drop in range and expect it to recover again next spring. The other thing that affects my range is Head lights and Wipers. Having both a smaller 12V battery and a smaller Traction battery the need to keep the 12V battery charged to power the Lights etc can just be seen in the range. It's not enough to carry a much bigger 12V battery just to power the lights and wipers though. No heater in a Twizy so that doesn't affect the range.
 

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The pressure in your tyres has dropped, the car is probably muddy which affects drag, you're using the heater, the roads are often damp, your battery is cold. All of those things add up....!
 

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Our range drop is much the same as we experienced with the Leaf. It's to be expected - at least by those who've done their homework! I haven't found preconditioning to make much difference to range. But then we haven't had any really cold weather yet.
 

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It's made worse if you have the resistive heater and haven't purchased the heat pump option on the i3. The latter is standard on the Acenta and Tekna Leafs now.
 

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In theory the battery pre-conditioning in the winter pack should mitigate some of this loss.... does everyone here have that option?
 

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BMW i3 Rex
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It seems that it does have the heat pump - but without the refrigerant to air heat exchanger. It ought to be possible to retro-fit one somewhere. But so far - if the guessometer is to be believed - the range drop with modest heating appears to be far less than we saw on the Leaf.

Edit: Correction: Misinterpreted the diagrams. The heating components are the same for all versions with just the heat pump and an exchanger added when necessary. Retro fitting might be mechanically possible but there's a LOT of control software.
 

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Ok that's a shame - seems like it would be useful to have.
It's because on the BEV the HP is located where the REx would be.
 

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i3 with Range Extender (EREV) Sept 2014
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My E range before REX kicks in has gone from 69 miles to 66 miles recently in my almost 2 month old car if that helps. I use preconditioning but only for 1st trip each morning which varies.
 

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Range seems to slipping away as it chills down here.

I had my i3 back in March so this isn't my first foray into the cold. IIRC, there were even a few frosty mornings back then.

Irritatingly, I've had a s/w update between times and that seemed to make predicted range (but not, I think, actual range) a lot more pessimistic - so comparisons between now and then are a bit meaningless.

However, I do think that predicted range seems down on March - even allowing for the s/w update. Unless the update made it more sensitive to external temperature. Or maybe I've got more liberal with the heating (probably! - I was a real amp-miser originally).
 

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Discussion Starter · #16 ·
Well preconditioning certainly helps - I have tried to precondition for the last 2-3 trips & I'm "beating the predicted range" quite easily & the predicted range has gone up to about 70 miles.

However surely it can't be cabin heating that makes the difference - I would estimate the power consumption to be an order of magnitude below the mileage effect I see, so it must be this 'battery preconditioning' feature that came with my winter pack.

Does anyone know what this does - or how long I should pre-condition for if I use the remote app to switch it on? Does the battery have to be warmed for best performance? - I would have expected it to improve with lower temperature as internal resistance [usually] falls with lower temp.
 

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AFAIK internal resistance usually falls with increasing temperature. Although it would seem that the battery should be warmed I don't see any provision for doing so in the manual, only cooling loops in the battery compartment to keep the temperature below 30C.

It may be that preconditioning using the battery heats it a little anyway. When I've used preconditioning 15 mins seems enough.
 

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It's definitely the weather.

When I bought my Ampera in June I got around 48 miles for the daily stuff. Now it's down to 39. Because the Ampera only uses part of its battery capacity, I know this is down to a number of factors:

  • Cold air
  • Use of heater and heated seats
  • Wet roads increasing rolling resistance
 

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The diagrams show all the heat pump components located up front, nothing in the REx space. BMW's statement is that the pump is not on the REx for weight reasons, but it can't weigh that much!
Dug a bit deeper - the heat pump condenser is where the REx fuel tank is, so there are "packaging issues" putting both in. That's not the same things as wot I said, so I stand corrected.
 
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