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Great data Matt. Aside from changing batteries were there other major mods that might affect efficiency?
How much did the weight change? Assuming you didn't change anything else then we have a good long term test that shows an approx 30% gain in efficiency primarily through weight reduction.
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
There was no weight change, I was after more range rather than less weight :D
The 30% gain was the difference in operating efficiency between nimh batteries and cheap LiFePO4 batteries.
nimh has poor round trip efficiency
re aerodynamics,
about the only way to improve is reducing frontal area, I agree.
The more you try to improve the drag coefficient, the more the bike is affected by side winds and the less the bike wants to change direction.
Bikes just plain have bad aerodynamics.......
btw - I have been playing around with Sevcon controllers recently,
They're very impressive in that they can drive a generic BLDC hub motor, with only hall sensors for position sensing, but still produce a sine wave.
There is an improvement in efficiency, but the major advantage is top speed is no longer limited by battery voltage.
This allows you to have peak power well before top speed (Much like the Vectrix).
Matt
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
I think this is fine - a long as it is made very clear what the consequences of the change are.
Interesting use of first-person in this remark.
Of course, if errors develop in the SOC calculation you also "disable" (strand) them even though the pack is not near depleted; if spurious signals come from any of a number of sensors malfunction from the side stand to the battery pack, motor cable and motor temperatures you disable them...
This is why I have come to call Current's BCU the "Nanny Box".
Wow! After I posted that I thought "hmm, well of course Li is more efficient not just lighter" - but I never imagined the whole 30% was due to that difference. (Don't tell Mik! ;-) - hey, that's just a friendly joke)
I agree that the *easiest* way to improve the CdA is to go after the A first. However, I'm not convinced that some reasonable reduction in Cd via streamlining can't be achieved without turning a bike into a "susceptible to crosswind / difficult to ride" nightmare (which is why I want to try it myself - at which point I'll probably just come back and say "hey, matt, you were right!" ;-)
Very interesting about that sevcon controller! When we approached them to ask to *buy* a sample they basically ignored us (and we tried pretty hard not to be ignored). We took that as a bad sign. What model of Sevcon controller? And did you buy it direct?
I'm sure the Sevcon is much more sophisticated than the Kelly (night and day really) - how do you think the price and features compare (i.e. is the sevcon worth the extra money?). I think you've got a fair amount of experience with the Kelly KBL series, right?
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
Ouch!!! Harsh, but I have to say fair. ;-)
SoC calculation is much improved in latest version of the "Nanny Box" software - it's in testing right now (and will then be rolled out to all customers).
However, note that we don't strand them based on the SoC calculation - only based on the LVC. We do limit throttle based on SoC calc.
Paul - I know your position on "nannying" (and I respect that position) but you have to realize that when we sell these to "regular folk" they will expect us engineers to prevent them from shooting themselves in the foot (so to speak). Not everyone is going to be as EV savvy as you, nor will they follow instructions - so we have to put this stuff in place. Think of it as a "necessary evil".
John H. Founder of Current Motor Company - opinions on this site belong to me; not to my employer
Remember: " 'lectric for local. diesel for distance" - JTH, Amp Bros || "No Gas.
Its actually worse than that,
to get the losses down to 30%, I had to recharge less than a couple of hours before use and don't charge beyond 80%.
When I just recharged overnight, I lost more, but I can't find the log I used to keep to say exactly how much.
Don't let me dissuade you from trying, I too would be interested in the results.
Oh, I can't buy direct either, I don;t even show up on their radar :)
The sevcon is used in Vmotos/Emax newest scooters
The major advantages are smoother take off, higher efficiency, and of course higher top speed.
In theory it can also use field strengthening at low speed to increase power on take off, without additional motor amps (but more battery amps of course).
It should be noted, that when the controller is using field weakening to increase motor speed, the motor output is less stable, and less efficient, than if just using a kelly.
Most of the additional heating is in the motors permanent magnets though, which are fairly easy to cool.
I do quite like the Kelly KBL series, simply because replacements are cheap and easy to come by, and modifying the settings is easy.
The Sevcon requires a fancy programming cable and software.
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
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