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[Richard230]

Protomech has speculated that Zero might up the voltage of their models in the near future.  But I wonder if the Z-Force motor will be able to handle higher voltage, with regard to heat and rpm?  I just don't see Zero tossing the motor design and designing and building something new.  They supposedly spent some $900,000 developing this motor and I would think that they plan to use it for some time.  I suppose that it could be water-cooled, but does anyone care to speculate on the power limits of their motor and what could be done to improve it while sticking to its basic size, shape and design?

[dkw12002]

I hope they don't water cool it. That adds more weight. Really the thing that heats up ICE bikes so much is idling, but electric bikes are just the opposite. Essentially no heat is being generated at long stop lights. Maybe some better air channeling to cool down the motor if that's an issue. The vents along the side of my 2013 S are for cooling down the battery, but the motor is tucked behind the battery where it doesn't get much air directed toward it. It looks like some additional vents toward the back of the side fairing would direct more air toward the motor. 

[Richard230]

I agree, and it seem like it would be easy enough to do.  But motor heating must be an issue as the 2014 gauge allows you to watch the motor heat up when it is under stress and the owner's manual seems to indicate that motor heating will result in power drop-off. 

[NoiseBoy]

They would just have to reduce motor current accordingly to keep it within cooling limits. Increasing voltage wouldn't necessarily be to get more power, it increases the efficiency of the drivetrain and chargers and means the bike could use chademo more readily as well as being potentially lighter due to thinner gauge cables.

[ultrarnr]

Engine heating is only a problem at high speeds. If you get the S or SR up to around 90 + MPH after awhile you will see the engine heat warning light begin to flash. You can still hold that speed for a short time but if you don't slow down at some point the electronics will take over and cut your speed for you. This is the reason why Zero lists the max speed on an SR at 102 MPH but max sustained speed is 85 MPH.

[protomech]

Any efficiency gains will be very very small - resistive losses will decrease, but they're sub 1% of power used by the bike.

Lighter cables will be nice. Weight improvements may be balanced by additional protection needed at higher voltages.

The big advantage would be improving compatibility and speed of DC quick charging. Primarily CHAdeMO today, and not well established in the US but growing quickly. Nissan is starting to install these at their dealerships in my area at a fairly rapid clip .. it's conceivable by 2015 or 2016 that CHAdeMO or CCS charging stations could be established along several common routes.

***

Zero would need to change their battery strategy somewhat, find smaller cells from Farasis, or find another battery supplier. Current bikes use 1-5 ZF2.8 modules in parallel, each module is 28s1p 25 Ah cells. Zero could use existing cells as 56s1p modules (ZF5.7) or 56s2p (ZF11.4) or 56s3p (ZF17), but that does limit their possible configurations.

They'd need to change their motor. This can be done by changing the windings, I don't think it'd be hugely expensive to do.

They'd need to change their charger. Zero uses a 2s2p configuration of meanwell HLG-320H LED controllers to charge their S, DS bikes. They could use 4s1p across the board, but this would be a great time to move to a higher-power charger and standard J1772 charging capability.

They'd need to change their motor controller, and I don't think there are many high-voltage inexpensive controllers suitable for an EV (Zero probably pays ~$600 for their Sevcon G80 controllers). This is probably the big factor preventing them from going higher voltage. Sevcon has one higher-voltage range, G120, which operates at up to 150 volts (35s maximum) but may not be widely available. Curtis 1238 ($2000 list) maxes at 130V, 1239 ($2700 list) maxes at 170V. If you have unlimited pocketbook, for example building a race bike, there are a wealth of high-buck high-power high-voltage controllers. Zero needs low-buck low-power high-voltage.

***

Probably the Sevcon G120 makes the most sense for Zero for a new 2015 model. Slightly higher voltage - by about 25% - but requiring only small changes to the bike.

35s1p modules would be 3.2 kWh each (ZF3.7). Standard DC charging and 3kW J1772 would add maybe $1500 to the bike cost. Higher module counts would add perhaps $500 per module.

Here's my guess at possible configurations:

1 module 3.2 kWh FX ZF3.7 $11500 (probably not worth offering .. how well is the $9500 FX ZF2.8 bike selling? probably not well)
2 module 6.4 kWh FX ZF7.4 $14500 (would Zero change this to a fixed-module bike? they've scrapped the FX/MX bikes for 2014, will the FX continue for 2015?)
3 module 9.7 kWh S/DS ZF11 $16000
4 module 13.0 kWh S/DS ZF14.7 $19000

Add $2000 for the SR.

Power would improve by about 10% - 50 hp FX, 60 hp S, 75 hp SR.

***

The comparison between the 2014 S ZF11.4 and the 2015 S ZF11 is the most interesting one IMO.

Price increases by $1000, unless Zero can find other ways to reduce costs (probable).

Capacity and range slightly down.

Width would increase slightly. Weight would probably be about the same. Maybe slightly lighter (couples nicely with the extra power).

Charging speeds would be much higher. 3 kW AC would be a 3.3 hour charge 0-95%. DC could charge at up to 14-17 kW for a ~30 minute 80% charge (ZF11) or ~40 minute 80% charge (ZF14.7) ... provided that the DC charger supports voltages as low as ~120V and offers up to 125A charging. The chargers Nissan is installing will, but many others will not.

I think most 2013-2014 ZF11.4 owners would pay an extra $1000 for those features.

***

I don't know if Zero will go this route for 2015 .. a 25% voltage bump will not make them fully compatible with CHAdeMO chargers, and I think they need near-universal compatibility before they can offer the CHAdeMO inlet as a standard option.

But I hope they do .. I'm looking for DC quick charging on my next electric bike.

[kingcharles]

If a higher voltage MC is not available at a decent price, then maybe they should design their own?

Or buy the Vectrix remains (chapter 7 since a few days) as the Vectrix designed MC goes up to around 170 volt if I remember correctly.
And get their hands on the multi function throttle patent at the same time?

[NoiseBoy]

The obvious solution would be series modules together.  That way they could keep the same battery building process.  Whether the Farasis cells can provide a high enough charge/discharge rate to maintain 440A in that configuration I don't know.  It would limit your choice to either 8.5 or 11.4+Powertank though.

A 25% increase seems like a waste of time to me as it still doesn't allow universal DC charging compatibility.  400V for cars and 200V for bikes seems like a neat solution.