I took my electric conversion trike for my first serious range test yesterday and unfortunately got stranded with a dead battery. =[ So I had two main questions in this thread. My first is about voltage drop for batteries.
Is voltage drop linear?
I built my battery out of tesla 21700 cells. Anyway, I went on a trip that was 28 miles one way. When I got to the 28 miles, my voltage went from around 108 volts down to around 95. However on the way home, it went from that 95 volts down to the low 70s, at which point it was dead. So that's quite a significant drop on the ride back. That means I dropped 13 volts during the first 28 miles. Then on the way home it died about 17 miles in, which means it dropped a further 21 volts in just 17 miles (95v down to around 74).
So my question is, is this normal? Do lithium ion batteries' voltages drop faster as they lower? meaning, it's not a linear drop off? In other words, a 109v fully charged battery, and 74v fully discharged, mathematically would be at 50% at 91.5 volts. But is this not really how the battery depletes in real world use?
If you have an electric build, what is your average watt hours per mile?
My machine is around 560 pounds, with a big 12kw QS hub motor in it. I was trying to drive very conservatively in order to conserve battery the whole trip. The math works out to around 150 watt hours per mile that I was getting. This was mostly back roads, with a speed of around 40 to 50mph. I'm a little disappointed with that number, I thought I would be able to get closer to the 100wh per mile mark. I don't have much regenerative braking settings enabled yet, but nonetheless I don't feel that would have made a significant difference given I was driving pretty easy. If anyone else has a similar motorcycle/scooter build, what types of WH per mile figures are you getting?
Is voltage drop linear?
I built my battery out of tesla 21700 cells. Anyway, I went on a trip that was 28 miles one way. When I got to the 28 miles, my voltage went from around 108 volts down to around 95. However on the way home, it went from that 95 volts down to the low 70s, at which point it was dead. So that's quite a significant drop on the ride back. That means I dropped 13 volts during the first 28 miles. Then on the way home it died about 17 miles in, which means it dropped a further 21 volts in just 17 miles (95v down to around 74).
So my question is, is this normal? Do lithium ion batteries' voltages drop faster as they lower? meaning, it's not a linear drop off? In other words, a 109v fully charged battery, and 74v fully discharged, mathematically would be at 50% at 91.5 volts. But is this not really how the battery depletes in real world use?
If you have an electric build, what is your average watt hours per mile?
My machine is around 560 pounds, with a big 12kw QS hub motor in it. I was trying to drive very conservatively in order to conserve battery the whole trip. The math works out to around 150 watt hours per mile that I was getting. This was mostly back roads, with a speed of around 40 to 50mph. I'm a little disappointed with that number, I thought I would be able to get closer to the 100wh per mile mark. I don't have much regenerative braking settings enabled yet, but nonetheless I don't feel that would have made a significant difference given I was driving pretty easy. If anyone else has a similar motorcycle/scooter build, what types of WH per mile figures are you getting?