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[teslatech]

"Battery voltage is decided, going to stay quiet about it for now, voltage tells a lot about a power system."
Power = volts * amps.  Does not matter what your voltage is.  The power bus on a motorcycle is only few feet at most.  Does not matter if the cells are in parallel or series they still have the same power.

Low voltage = safety for users/dealers/hackers

[NEW2elec]

Volts=speed
Amps=range
High volts=DC fast charging at lower temps
Ebergica 450V bike has DC fast charging in about 40 mins and a top speed of around 150MPH but range of about 60 miles.
Zero 117V charges in about 2 hours with max chargers with 100MPH top speed but around 140 miles range.
Other factors as well but it does matter.

[teslatech]

Power = speed/acceleration
Range = energy stored

Does not matter how you arrange the cells.  If a battery can do 1Kw(power) and store 1Kw/hr(energy) does not matter how you arrange them. 

Only thing volts gets you is smaller connectors and better use of DC fast charge systems, but a boost converter from vicor get you 4:1 voltage conversion have over 1kw per 1inch^2 density, so you could go easy 400v to 100v for charging. 

If you have winding control over the motor, the total current in the tooth is the same if you have one set of wires with 100amps on it or 100wires with 1 amp on it, the trq will be the same.  The total amount of copper the electrons are pushing though is the same.

[togo]

Yup, volts only equals speed in primitive DC drivetrains. Variable frequency drives are what all the efficient EVs use.

[Doug S]

I think the "volts = speed" conception comes from 10-20 years ago, when people were kludging their own EVs together. If you take an off-the-shelf electric motor, designed for say 96VDC, and you overdrive it to 120VDC, you WILL get more power and torque out of it. In fact, for any given electric motor, more volts really does mean more current, more torque and more power...right up until the smoke starts escaping from the motor.

Proper design of a commercial vehicle doesn't allow that sort of shenanigans. When DESIGNING a vehicle, all specs must be observed because long-term reliability is exceedingly important, and voltage vs. current really does become just another design option.

[Richard230]

I think the "volts = speed" conception comes from 10-20 years ago, when people were kludging their own EVs together. If you take an off-the-shelf electric motor, designed for say 96VDC, and you overdrive it to 120VDC, you WILL get more power and torque out of it. In fact, for any given electric motor, more volts really does mean more current, more torque and more power...right up until the smoke starts escaping from the motor.

Proper design of a commercial vehicle doesn't allow that sort of shenanigans. When DESIGNING a vehicle, all specs must be observed because long-term reliability is exceedingly important, and voltage vs. current really does become just another design option.

My 2010 Electric Motorsport GPR-S had a large 36/48 volt sepex motor installed in the bike. My guess is that it had been yanked out of a golf cart. It was running 72 volts and when I inspected the armature it was covered with a ring of burn marks. That thing must have really been sparking at its top speed of 60 mph.

[NEW2elec]

Well the Porsche Taycan is going to run at 800V and charge in 15 mins (on it's own charger) 600hp and 0-60 in 3.5secs.  The variable seems to be the hacker killing 800V.
So I'm sticking with voltage matters.   

[Michael Moore]

A concern that I've not seen mentioned that seems to be a common point of discussion on many marque forums is making it easy to have your vehicle fit someone outside the normal range of physique.

One riding position is not going to be good for everyone from 5'2" tall and 100 pounds (including gear) to 6' 2" and 250 (including gear).  Some people have very long torsos and short legs, others are long legged/long armed with a more standard torso.

Have multiple positions for the foot pegs on the stock mounting plates or handle bar risers that have the bar offset from the bolts that attach the riser to the front suspension can allow the risers to be reversed to move the bar closer/farther away.  It sounds like you've got a lot of in-house CNC capacity, maybe you could offer a few options on the foot peg plates or bar risers that would be normal dealer stock and used to tailor the bike to the purchaser.  On seats consider having different sets of seat brackets to allow some height or angle adjustment.

You can have your standard, large production quantity part be designed for the standard 90th percentile potential purchaser, but with your own CNC mill it is easy to have a few parts on each pallet be made to the alternate designs so you can have some available when needed.

I get concerned with the number of people I see buying (or cobbling together on their own) alternate suspension links to try and get the bike low enough so they aren't on tiptoe at a stop, because many of those people clearly have no clue that what they are doing could dangerously impact their ground clearance, wheel/fender clearance, or handling.

Also have a wide variety of people test the seat, because a lot of bikes seem to come with really poor seats.  There are people who make a living redoing seats so you don't start squirming in 15 minutes, it isn't rocket science.  And once you get a good seat that fits most bottoms, if you can make the seat adjustable for height or fore/aft position then the customer isn't POd because they've got to go out and spend $400 on their new bike to get the seat redone so they can stand to ride the bike.

The motor driveshaft is the pivot point for the swing arm so the belt maintains a constant tension and there is no on/off throttle snatch.

Courtney, you may want to take another look at your BMW.  The swing arm pivot is on the outside of the motor case so the motor moves up and down with the swing arm as on many scooters.  In this photo you can see the pivot tube at the vertex of the L-shaped bracket bolted on to the battery box/chassis.



cheers,
Michael

[cpallenjr]

Yes Michael you are correct - but the belt is still under constant tension without any slop, and the unsprung weight is well managed.

[Michael Moore]

Courtney, I think BMW did a good job on the C Evolution, there are lots of nice/clever features.  I spent some time going through a parts fiche to find details on the design.

But unless the OP wants to copy some of those clever features we're probably getting a bit off his topic.

cheers,
Michael

[togo]

Well the Porsche Taycan is going to run at 800V and charge in 15 mins (on it's own charger) 600hp and 0-60 in 3.5secs.  The variable seems to be the hacker killing 800V.
So I'm sticking with voltage matters.   

Of course voltage matters.  Higher voltage lets you pump more watts through the same resistance.  So it gets more power between battery and controller with less waste heat, or it gets more heart-stopping current into your body.  But it doesn't matter the simplistic way a lot of the old DC-drivetrain hackers think it matters.

[cpallenjr]

Doesn't higher voltage also mean smaller wires for a given wattage due to reduced current flow? That would seem like an important design consideration.

[netdomon]

  wow

[Alan Stewart]

Well the Porsche Taycan is going to run at 800V and charge in 15 mins (on it's own charger) 600hp and 0-60 in 3.5secs.  The variable seems to be the hacker killing 800V.
So I'm sticking with voltage matters.   

We really are way off topic! The Tesla P100D is good for 760 HP and  2.5s 0-60, 10.7s 1/4 mile, all at 400v.

[Alan Stewart]

Back to the original topic... The electric bike I am most likely to pull the trigger on, if they ever make it, is the Alta ST prototype. Pretty, light, adequate battery for my use which would be intown Atlanta errands and an occasional short ride in the countryside on some less-traveled roads. I’ve never been fond of Zero’s styling. No commuting, the car is safer and more comfortable for my daily 40-mile journey in heavy traffic. Built-in L2 charging is a requirement.

I’d recommended a deal with Tesla and compatibility with their superchargers for those that want to go touring. The same charge rates that Tesla cars achieve shouldn’t be necessary, just access to all those well-placed charging sites.