Too Busy For Words - the PaulWay Blog

Fri 19th Sep, 2014

Learning as we go

Today I broke my record for distance on the electric motorbike: 70km on a charge.

The battery at the end of that was at 121.8V, which is about 3.2V per cell, and the lowest cell was 3.16V. Watching the voltage as I was riding (taking quick glances) showed that even under load it wasn't dipping below 110V, so there's a good chance that most cells were still running just fine. It's possible that there's a cell with lower capacity, but I think as I ride it and the battery gets more chance to level out I'm actually improving its range.

Unfortunately the battery meter on the bike thinks that power is leaking out when it isn't, so that doesn't tell me much. The meter on the BMS read "0%" at 38Km (the last time I read it) and "0%" before I started charging it, so I have no idea whether that's being caused by a low cell or some other random error. Either way, it's still trial and error to see how much distance I can actually get out of the battery.

According to the meter on the wall socket, that was half a kilowatt-hour. According to my calculations, that was about 11 amps at 120 volts over four hours, so about five kilowatt-hours. Either the decimal point is wrong on the meter and it's an order of magnitude too low, I'm reading it wrong, or it's just plain incorrect. Five kilowatt-hours is in the right ball park. At $0.17 per kilowatt-hour I just paid 89 cents to fill up the bike. So it's about 1.2 cents per kilometre, at this rough guess.

Interesting!

The other amusing thing is that I'm having to get used to coming back to the bike to find people peering intently at it. Fluoro-clad workers, motorbike enthusiasts, general passers by - I get all types. There are still lots of people who walk on by, so I don't think I've really changed the planet. But it's still fun to explain it and to see people's different reactions, all without exception positive. That's pretty cool.

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