My first (semi) EV project
Posted: Sat Aug 09, 2008 8:26 pm
Last year I set about converting by recumbent bike to electric assist. I thought some might be interested in how it turned out.
The original bike was a fairly typical Taiwanese under seat steering SWB recumbent. I fitted a very light weight (2.5kg) motor to the 20" front wheel. To prevent the motor spindle from opening up the forks, I made up a stainless torque plate:
The battery was made up from a LiFePO4 pack bought from an eBay seller and has proved to be excellent. It is a 36V, 10Ah pack and was around £150 complete with charger and shipping. Here are some pics of the pack as it arrived, the battery management system and the final epoxy glass case I made for it:
I made up a "dashboard" for the bike which has the power switch, light switch and a wattmeter. The wattmeter was adapted from a RC model one and shows battery voltage, current and Ah used, so is quite useful. It was also fairly cheap, at around £35 from eBay (I've used a similar one with a higher current rating on the Yamaha project). Here's a pic of the "dashboard":
I added an ordinary bike computer to it to give me an idea of speed.
Finally, here's a pic of the finished 'bent and a close up of the under-seat mounted battery:
The electric conversion adds about 6.5kg in total to the weight of the bike. It gives a very useful assist up to about 15mph, then runs out of puff. I use it mainly for hill assist - I've yet to find a hill that it won't power up without me pedalling, which is a great boon, as hill climbing is not my strong point.
Jeremy
The original bike was a fairly typical Taiwanese under seat steering SWB recumbent. I fitted a very light weight (2.5kg) motor to the 20" front wheel. To prevent the motor spindle from opening up the forks, I made up a stainless torque plate:
The battery was made up from a LiFePO4 pack bought from an eBay seller and has proved to be excellent. It is a 36V, 10Ah pack and was around £150 complete with charger and shipping. Here are some pics of the pack as it arrived, the battery management system and the final epoxy glass case I made for it:
I made up a "dashboard" for the bike which has the power switch, light switch and a wattmeter. The wattmeter was adapted from a RC model one and shows battery voltage, current and Ah used, so is quite useful. It was also fairly cheap, at around £35 from eBay (I've used a similar one with a higher current rating on the Yamaha project). Here's a pic of the "dashboard":
I added an ordinary bike computer to it to give me an idea of speed.
Finally, here's a pic of the finished 'bent and a close up of the under-seat mounted battery:
The electric conversion adds about 6.5kg in total to the weight of the bike. It gives a very useful assist up to about 15mph, then runs out of puff. I use it mainly for hill assist - I've yet to find a hill that it won't power up without me pedalling, which is a great boon, as hill climbing is not my strong point.
Jeremy