Time for new batteries

I have been struggling with thundersky batteries for way to long and have decided to try a Lipo pack in the bike

Here is a picture compilation of the process from cells to pack in the bike. As of this writing she still isn't back together but will be in a few days.
The cells come from Hobby King Turngy four cell 5AH hard case packs. I'm building this up as a 8P 28S pack or 115 volts @ 40AH. We'll see how these fair over time and hopefully without any incidents

A second side benefit is the bike is losing over 50 pound of weight!

eFXC final race

Another great video from Andy

Street fighter build

We have had these rollers in the shop for a while just waiting for a time when we could build them up. With the Dual motor setup being a best seller we needed a demo bike to show off what the DU-600 series motors could do and how they look. So we took a GPRS extended the swingarm (150mm) and turned it into a street fighter style bike.

She is far from being finished but here is the bike outside after the first Frankinride using a 500 amp 144 volt Kelly controller. with a 96 volt Lipo pack capable of over 300 amps

Lots of work still needs to be done to make her a proper show bike but the foundation is there.
Customer reaction:

Two motors in a light weight frame = fast of the line

Race #2 Winton race track

EnerTrac continues it's sponsorship of the Catavolt team and Thanks to Andy of evmotorcycle.org we have a great video of the race event

EnerTrac sponsors the CataVolt race team

Dual motor Big bikes get a hub motor

 

Dual Motor/wheel setup in a swingarm

Multi speed motors and gear boxes

Now the question
What if you want to accelerate well and go fast?

lets all agree it takes the same HP to go say 100MPH regardless if there is a gearbox, multispeed motor or not

So there is no free ride here if the motor can't put out the power no gearbox or multispeed motor is going to get the bike to speed.
The power plant needs to be in a proper operating RPM to be efficient and output the power needed for the speed required.

If you have a wide torque curve as most electric motors do then maybe you don't need a gearbox or multispeed motor but even an electric motor has a most efficient RPM and that is up around 60 to 80% of the max RPM (BEMF) So even thought a gearbox may not be necessary, it will result in more HP because the motor is operating in its most efficient region. For a multispeed motor implemented correctly this is also true. Since a high wind count motor has more amp-turns it has higher torque for the same current (which will result in overheating if sustained) or half the current for the same torque (the correct way to look at it) but it trades speed for torque and will be voltage starved at half the RPM, So the 60% of max RPM is reached early and so does Max efficiency. Then if one switches to half the turns and doubles the KV of the motor it is now possible to get higher RPM and again achieve max efficiency.

In Conclusion more power is achieved with both the gearbox and the multispeed motor because the motor is spending more time at higher efficiency really no other reason, but the gearbox has losses that make the gain in motor efficiency sustainably less power to the tire. The gearbox losses are not present in the multispeed motor design.