Originally Posted by
kracksmith
Super nice choice to pick a titanium frame for your build, it's light and strong made to hold up well over time. Just a few questions
- Approximately how much does it weight with just motor and battery
- Where did you get your 52v 49ah battery, largest capacity i could fine was a 21ah
- What kind of motor, looks nicely sealed too
Ebike/Emoto both are just too expensive to get speed and distance right now and the limitation is mainly the cost of the battery. For now I won't even consider purchasing an emoto such as a Onxy or Sur ron due to their overall cost, as battery has a life of 800-1000 recharge cycle from empty to full then needs to be replaced. Good Emoto batteries are very expensive too, 2500. I maybe entertain with a Super73 though someday. I would say the same for a Telsa. Tesla owners will face the same thing after 8-10 years where they will need to make a decision to either buy new batteries or just get another Tesla and make payments all over again. Hybrid cars could be more ideal if they make them go faster and design better. Replacing a smaller battery on this wouldn't cost a fortune.
I still think I made a right choice of building a Ebike just for the loving sake of putting a kit in a bicycle. So for now I will continue to ride and enjoy my ebike as a pedaling bicycle and use PAS and throttle when needed.
Thanks for sharing your awesome pictures, looks fun and adventurous out there.
My apologies, I know that I typed a response to this post, but I don't see it here so I will type one again.
With just the motor and batteries the bike weighs 75 lbs
The 49 amp hour battery is actually 4 batteries in parallel. The four batteries act as one huge battery and I charge them all at once. They basically have the same voltage all the time. Each battery has its own BMS and I generally charge through each BMS. I have a harness with four bayonet plugs on it and plug in each battery. I have fuse links to all batteries. I cannot accidently plug in one battery to the full 15 amp charger or the fuse will blow. The fuses are 7.5 amp. I have to plug all the batteries in before connecting the charger. I have accidently had the charger on and started to plug in batteries. After the second I realized what I was doing and sure enough both fuses were blown.
The motor is a standard Bafang BBSHD 120mm wide bottom bracket. I made custom fairings around it to protect it from spray and crud from the tires. I also have fairings behind the batteries to protect them from water intrusion.
Most of my riding is done below 20 mph. The last ride out I averaged 12.7. The bike will maintain 20 mph if I want it to, even on moderate grades. I can even maintain 25 with slight hills. Maintaining 28 mph is stressful to the system and has a danger of overheating in warm weather.
Maximum motor output under the right conditions is just under 1,100 watts. You have to have the right conditions to exceed 750 watts. As an example of what I mean:
Maximum power draw that I have seen from the batteries is 1,700 watts. To get 1,100 watts motor output requires that the motor be at max rpm (Cadence of 130 rpm) and max load (any more load will slow the rpm down) It's pretty hard to add any of your own power at 130 rpm so you are full throttle to get that motor output.
I have seen 1,700 watts battery draw at a speed of about 6mph climbing a sand dune at maximum stacking angle. Motor output was about 550 watts @ 170NM of torque.
All perfectly legal as the regs are written as motor output and not battery draw. Yes, you can be showing 1,700 watts on your meter and only be at 550 watts of motor output. That translates to an efficiency of just over 32%. The rest (67+) percent is quickly heating up your motor core and wiring and, is not sustainable for more than a few minutes.