Sounds stupid I know, Should Be Bigger Battery = More Energy To Charge It. Since switching from the 19Kwh Battery BMW i3 to the 41Kwh Battery Zoe its costing me less to run the car. With the i3 and its limited 85 to 90 Mile Range, I was forced to charge more often and these would most often be paid chargers. I reduced the cost by avoiding Ecotricity and using Polar Rapid Chargers which are a lot cheaper. Sutton in Ashfield M1 Jnc 28 to Central London and Back (145 Miles each way) BMW i3 89 Miles to Milton Keynes Rapid Charge Polar 17kw approx £1.80, then into Central London, Free Charge on Polar 7kw Post), on way back stop at Milton Keynes again Polar Rapid 14Kw approx £1.50, then home arrive home Empty. Overnight Charge 20kw at 5p = £1.00 TOTAL £4.30 (Plus depending on Season maybe £1 or £2 from the Rex Backup Generator Petrol) Same Journey in the Zoe 41Kw To Central London Non Stop 145 Miles, Charge on Polar 7kw Post Free, Return Home, On the way back I can go straight home and arrive with 20% Battery Left and plug in overnight 35Kw at 5p = £1.75. But being Tight I tend to stop at Leicester Forest East Services and plug into the free 22kw charger while I catch up with emails and phone calls. doing that I arrive home with about 70% Battery which reduces overnight charge to 12kw at 5p = 60p TOTAL £1.75 with No Stop or 60p with a Mooch Stop at LFE Its not worth doing the free mooch stop at LFE in the i3 as it can only charge on single phase AC (7kwh Max), where the Zoe can use 3 Phase and the free post can give it 22Kwh max). The extra range has really increased the charge stop options and I am now finding I can choose to look for Free Chargers rather than being forced onto whatever is available as I am at the end of my limited range. Checking my home usage my overnight charging has dropped by about 25% when I had expected it to nearly double. And my Polar Bills for Public Charging have halved.