With the 48 3.2V 200Ah cells I will have 154V, and 154V*200Ah*80% = ~25kW of available energy in my pack. That means I should be able to do about 71 miles based on 35kW to maintain 65mph (ignoring acceleration and any other factors). A little less than I wanted, and I’m really hoping it is enough to do 50 miles (round trip), including my “hill” so I can commute to work \/ gym \/ home and charge at work only. Otherwise, I’ll be dependent on charging at work and home, which won’t be a big deal.<\/p>\n Real life “Watts per mile” is another good estimate of range. Travis (who has a nice conversion I mentioned before) said he gets about 250Watts\/mile when driving conservatively. Based on that, and 80% DoD, I could get up to a 98 mile range. That likely won’t happen, but would be cool. A 300W\/mile estimate would give me an 82 mile range. My calculations are probably conservative, as I used higher values to not get my hopes too high. I’m excited to actually get my project together and find out what real data I actually get.<\/p>\n I’ve basically gone from zero EV knowledge a month ago to knowing “a little bit”. I’m still learning as I go…<\/p>\n","protected":false},"excerpt":{"rendered":"![\"201005021312.jpg\"](\"http:\/\/www.corbinstreehouse.com\/blog\/wp-content\/uploads\/2010\/05\/201005021312.jpg\")
I’m going with a 154V DC system and 48 Thundersky Lithium Iron Phosphate batteries. The nominal volts per lithium battery is 3.2 V. What Ah do I need per cell? At 65mph on flat ground will consume about 23kW of power (31Hp). 100 miles at 65 mph = 1.54 hours, or 1 hr 32 minutes. 23kw*1.54 = 35.4kw needed. 35,400 watts \/ 154 v = 230Ah. We want to only run the pack to 80% “Depth of Discharge” (DoD) to avoid killing the pack too early. So, at 230Ah I need 230Ah* 1.2 = ~275 Ah cells to make it work (roughly). I’m actually planning on using 200Ah cells (due to size and cost), so I won’t be able to get that far. Also note that batteries have cycle life<\/a> associated with them– you get more cycles and more life depending on how far you discharge the pack, and how fast you discharge a pack (the C rating). From my research, it appears that 1\/2 C is the best rating for the maximum cycle life, but are usually rated continuous at 2C. I’ll be pulling less than that, so I should be okay.<\/p>\n