osaland said:Just Bought my bmw i3, and the range is just to short for my use. 50 more km would have helped a lot.
Hope bmw options to fit more batteries or makes it possioble to refit Rex for the people who did not buy it.
According to the BMW i3 Service Managers Workshop document, the 8 current i3 battery packs each weigh 55 lbs each for a total of 440 lbs (200 kg), making mass specific energy density 49.1 wh/lb, or 108 wh/kg. Your math is correct. A 100 kg increase in battery capacity would result in something less than a 50% increase in range, since we all know the extra weight results in a loss of 5% (as measured by BMW) to 6% (as measured by the EPA) efficiency.Boatguy said:...At 100w / kg, 100kg is 10kw or a 50% boost in i3 range; say 40 miles for a total range of 120 miles (192km).
Not me!Boatguy said:Who would switch to BEV?
ultraturtle said:According to the BMW i3 Service Managers Workshop document, the 8 current i3 battery packs each weigh 55 lbs each for a total of 440 lbs (200 kg), making mass specific energy density 49.1 wh/lb, or 108 wh/kg. Your math is correct. A 100 kg increase in battery capacity would result in something less than a 50% increase in range, since we all know the extra weight results in a loss of 5% (as measured by BMW) to 6% (as measured by the EPA) efficiency.Boatguy said:...At 100w / kg, 100kg is 10kw or a 50% boost in i3 range; say 40 miles for a total range of 120 miles (192km).
Cramming the volume of not only the additional battery space, but its supporting coolant system into the tiny space occupied by the REx is the greater challenge, so I would propose that (assuming the unlikely probability that the battery modules in their current form factor, and the coolant system would fit) a two module, a 25% increase in battery capacity might be the more realistic suggestion. This might inch range up from its current EPA rating of 81 miles to 98, taking into account a 3% reduction in efficiency due to the additional weight.
Not me!Boatguy said:Who would switch to BEV?
possen said:I have opted for the BEV, but I would like a removable battery(s) in the space where the REX goes. That way if you need to go longer distances you only pay for the weight when you need it (unlike the REX). Also, I don't think you necessarily have to have those modules cooled the same way the main batteries are. Nissan and VW don't temperature regulate their batteries. Swapping these would be easier than the method Tesla employs with their battery swap technology and would add a lot of flexibility, where they could be traded and swapped along longer routes. The total weight of the extender batteries would not weigh more than the REX. Each module would be light enough for anyone to lift them. Only problem I see, is you might have to remove items out of you trunk to replace a battery. This definitely could not be retrofitted into current BEVs.
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