Originally I built a 15-pound lead-acid battery (described in a previous post) for Thea’s bike. This fall I began experimenting with lithium polymer (“lipo”) batteries, the same type of battery used by Radio Control enthusiasts. Not only are lipo batteries lightweight and inexpensive compared to my LiFePo4 and lead-acid batteries, they have a much higher discharge rate. This makes it possible to have a very small battery that can output enough amps to propel an ebike. So on Thea’s bike I replaced the three heavy 12v 10ah lead-acid batteries in series (a 36v battery) with two lightweight 18.5v 3ah lipos in series (for a 37v battery). Here’s the score: the lead-acid battery is 15 pounds, $100, 360wh, with a 36 mile range. The lipo battery is 2 pounds, $50, 108wh, with a 10 mile range. Which is better? It depends. My bike needs more range and weight is not a problem, so lipos are not a good option for me. But for Thea’s bike the lipo’s low weight is very appealing and their short range is not a problem.

Originally I built a 15-pound lead-acid battery (described in a previous post) for Thea's bike. This fall I began experimenting with lithium polymer ("lipo") batteries, the same type of battery used by Radio Control enthusiasts. Not only are lipo batteries lightweight and inexpensive compared to my LiFePo4 and lead-acid batteries, they have a much higher discharge rate. This makes it possible to have a very small battery that can output enough amps to propel an ebike. So on Thea's bike I replaced the three heavy 12v 10ah lead-acid batteries in series (a 36v battery) with two lightweight 18.5v 3ah lipos in series (for a 37v battery). Here's the score: the lead-acid battery is 15 pounds, $100, 360wh, with a 36 mile range. The lipo battery is 2 pounds, $50, 108wh, with a 10 mile range. Which is better? It depends. My bike needs more range and weight is not a problem, so lipos are not a good option for me. But for Thea's bike the lipo's low weight is very appealing and their short range is not a problem.

Originally I built a 15-pound lead-acid battery (described in a previous post) for Thea’s bike. This fall I began experimenting with lithium polymer (“lipo”) batteries, the same type of battery used by Radio Control enthusiasts. Not only are lipo batteries lightweight and inexpensive compared to my LiFePo4 and lead-acid batteries, they have a much higher discharge rate. This makes it possible to have a very small battery that can output enough amps to propel an ebike. So on Thea’s bike I replaced the three heavy 12v 10ah lead-acid batteries in series (a 36v battery) with two lightweight 18.5v 3ah lipos in series (for a 37v battery). Here’s the score: the lead-acid battery is 15 pounds, $100, 360wh, with a 36 mile range. The lipo battery is 2 pounds, $50, 108wh, with a 10 mile range. Which is better? It depends. My bike needs more range and weight is not a problem, so lipos are not a good option for me. But for Thea’s bike the lipo’s low weight is very appealing and their short range is not a problem.