steveCA
10 mW
I’ve used some of these beautiful spring months tinkering in the shop. I was always unhappy with having to abandon the front hub battery design that came from Wavecrest. I thought it was a very elegant solution for appearance, balance, handling, etc. There was much else about the bike I did not like, however. It was overly complicated and underpowered at 36 volts. And, it didn’t have enough amp hours for me, not enough range.
So! Here is one man’s attempt to provide an alternate solution that provides everything the hub battery did, (except for the elegance and aesthetics), and perhaps a bit more in the area of power and range.
In the attached photos, you’ll see two 15 ah Lipo’s slung low on each side of the front wheel, hanging off an extended set of buddy pegs. The battery boxes where the hard part. They had to be very strong, yet very light weight. I machined them out of 3/16†rectangular aluminum tubing. Pretty heavy stuff, but I lightened them up by almost half by drilling and machining out about 40% of the material. The battery boxes and mounting HW weigh about a kilo each and each battery is 15 ah, at 15 lbs. That’s 17.5 lbs hanging on the buddy pegs. I changed the axle to a solid 10mm instead of the quick release the frame came with. It is plenty strong enough to support the weight. The batteries are supported inside the boxes with cushioned pads that do not interfere with air flow too much. I’ve been riding it all over the place, and so far no problems. The bottom of the battery boxes do not touch the ground, even when I’ve got the bike leaned pretty far over into a corner (although, I’m sure you could get it over far enough to make it hit, if you were really trying to do that). The batteries are 48 volts in parallel, with a Shottky diode between them to keep them in balance on discharge.
The bike is now supported by the stock kickstand, and handles beautifully with the weight so low, and with the bike balanced front and rear. If I really wanted more range (45 miles), the rear rack slide is still available for yet another 15 ah if needed, or other gear perhaps.
This gives me more than enough range to make my 20 mile commute to work each day, with no lugging in a battery and charging it at work.
Flat tire problems remain the biggest downside risk to bike commuting for me. (My wife disagrees, she still insists that the biggest risk is getting run down by a pissed off CA driver!).
Comments welcome!
So! Here is one man’s attempt to provide an alternate solution that provides everything the hub battery did, (except for the elegance and aesthetics), and perhaps a bit more in the area of power and range.
In the attached photos, you’ll see two 15 ah Lipo’s slung low on each side of the front wheel, hanging off an extended set of buddy pegs. The battery boxes where the hard part. They had to be very strong, yet very light weight. I machined them out of 3/16†rectangular aluminum tubing. Pretty heavy stuff, but I lightened them up by almost half by drilling and machining out about 40% of the material. The battery boxes and mounting HW weigh about a kilo each and each battery is 15 ah, at 15 lbs. That’s 17.5 lbs hanging on the buddy pegs. I changed the axle to a solid 10mm instead of the quick release the frame came with. It is plenty strong enough to support the weight. The batteries are supported inside the boxes with cushioned pads that do not interfere with air flow too much. I’ve been riding it all over the place, and so far no problems. The bottom of the battery boxes do not touch the ground, even when I’ve got the bike leaned pretty far over into a corner (although, I’m sure you could get it over far enough to make it hit, if you were really trying to do that). The batteries are 48 volts in parallel, with a Shottky diode between them to keep them in balance on discharge.
The bike is now supported by the stock kickstand, and handles beautifully with the weight so low, and with the bike balanced front and rear. If I really wanted more range (45 miles), the rear rack slide is still available for yet another 15 ah if needed, or other gear perhaps.
This gives me more than enough range to make my 20 mile commute to work each day, with no lugging in a battery and charging it at work.
Flat tire problems remain the biggest downside risk to bike commuting for me. (My wife disagrees, she still insists that the biggest risk is getting run down by a pissed off CA driver!).
Comments welcome!
