Post by lkraft92 on May 3, 2015 12:42:35 GMT -6
Last year i posted about an electrathon car that i was helping to build. well after two semesters, it is finally driveable. we had the last race of the season here in hays on friday, and we wanted to get the car driving by then. So me and and another team member worked all day thursday and through the night to get the car done. we worked on it for 24 hours straight to get it done by friday morning. We built this car to be the fastest in the state and i think we accomplished it. We use a Motenergy permanent magnet motor, an alltrax programmable controller, and two 24v lithium iron phosphate batteries in series for a 48v system. the first race we were going to use our normal lead acid batteries that everybody uses, because we know they work. we were not sure how the lithiums would perform, so we used the lead acids first to remove one variable from the car. well, at the start of the race, we drove 5 ft and had our chain come off. we got it put back on, and it cam right back off again. so took it back to the pits to fix it. come to find out that our freewheel assembly wasnt straight and the sprocket wobbled causing the chain to pop off. we were able to get the freewheeler changed for the second race of the day. since is was the last race, we decided to put the lithiums in and go for broke. when we put the lithiums in, we have to change the max output current to less than 60 amps because the BMS on our batteries have a 60 amp cutoff. if more than 60 amps are pulled, they cut off power. we get the batteries in and the crontroller programmed. we start the race and everything is working. we run the car for about 15 minuted with no problems. this car is so fast nothing can catch it. we were running about 30 mph were most other cars run <25 mph. nobody could pass us. then we ran into throttle problems. we use a potbox with a throttle cable. our cable kept slipping which decreased out thottle output. we know going into this race that out weak spot was the throttle setup, but we thought we had it fixed. unfortunately we kept having to fix the throttle cable and was never able to get it working right. other than the throttle and the freewheel, the car worked as expected. when it ran, it ran great. we were planning to put a body on it, but we ran out of time. we will try and tune it this week so the guys coming in next year will have a well working car. it has been a frustrating but awesome project and i am so glad i worked on it. im just going to be sad walking away from it at the end of this year due to me graduating in two weeks.