Electric bikes, the next step

[Mr. Dazzle]

Its further complicated by the fact you can overrate electric motors by a huge factor...you can double the power for a bit. The practical limiting factors are essentially just catching fire/melting (or cooking the electronics, same thing really) or physically tearing itself apart.

It's standard practice for EVs to have overrate and derate modes based on temperature etc.

[Yorick]

You do have to consider horsepower ratings on electric vehciles slightly differently. Unlike a piston engine an EV can produce peak power across most of the rev range...it essentially operates in 2 regions "torque limited" when the motor can put out peak torque, or "power limited" (at higher speeds) when it can output peak power. EVs essentially always have either full power or full torque available, depending how fast you're going.

Piston engines on the other hand only produce peak power at a narrow speed range.

In simple terms EVs are always in the power band.

It means an 8bhp electric vehicle has a lot more "go" than an 8bhp conventional vehcile. Imagine having an engine that was on cam at full power all the time...electric motors are a lot like that.

Paint it any colour you like, 8 hp will only do about 55 MPH.

[Mr. Dazzle]

Its more a comment on the nature of electric drive than anything.

Even if you were to say an electric bike is effectively twice as powerful as a petrol one - which it ain't - this particular electric bike would still only be as grunty as a tuned 125.

[Horse]

Paint it any colour you like, 8 hp will only do about 55 MPH.

And I'll say this again: my best ever - literally laughing out loud - biking moment was flat out downhill, overtaking a 911, on a Honda CG125.

If it's designed and sold as an urban commuter, anything more is a bonus.

[Mr. Dazzle]

I used to overtake people all the time in my 1 litre Nissan Micra with the engine turned off. There was a big hill on the way to work, if I started at the top at 70mph and switched off the engine (said Micra had no power brakes and no power steering) I would frequently overtake people in the fast lane

Someone did quite accurately point out it didn't really matter if it was a 1 litre Micra or a 3 litre BMW when the engine was turned off.

[weeksy]

You do have to consider horsepower ratings on electric vehciles slightly differently. Unlike a piston engine an EV can produce peak power across most of the rev range...it essentially operates in 2 regions "torque limited" when the motor can put out peak torque, or "power limited" (at higher speeds) when it can output peak power. EVs essentially always have either full power or full torque available, depending how fast you're going.

Piston engines on the other hand only produce peak power at a narrow speed range.

In simple terms EVs are always in the power band.

It means an 8bhp electric vehicle has a lot more "go" than an 8bhp conventional vehcile. Imagine having an engine that was on cam at full power all the time...electric motors are a lot like that.

Paint it any colour you like, 8 hp will only do about 55 MPH.

But as a city commuter bike that's all it needs to do. If you live 2-3 miles from town or even a couple of back lanes from town, it's perfect. Plenty of people commute from one side of London to the outskirts on the other side without ever seeing more than 55.

[weeksy]

https://www.motorcyclenews.com/news/ele ... atteries/9

Swappable batteries on the horizon: Giants team up to make swap-in, swap-out battery packs a reality

Honda, KTM, Piaggio and Yamaha have signed an agreement to create a ‘swappable batteries consortium’ with a view to standardising batteries in electric bikes. Battery standardisation has been one of the key stumbling blocks to electrification, but it looks like this will finally be overcome.

[Nordboy]

https://www.motorcyclenews.com/news/ele ... atteries/9

Swappable batteries on the horizon: Giants team up to make swap-in, swap-out battery packs a reality

Honda, KTM, Piaggio and Yamaha have signed an agreement to create a ‘swappable batteries consortium’ with a view to standardising batteries in electric bikes. Battery standardisation has been one of the key stumbling blocks to electrification, but it looks like this will finally be overcome.

Potentially a great idea and size permitting could transfer to cars. Instead of stopping for fuel, stop at the ‘fuel’ station, swap batteries and off you go again.

[Horse]

Worth noting that the agreement also included reference to some other electric vehicle applications too.

[Mr. Dazzle]

As we've discussed before, either up there ^^^ or elsewhere on the forum, it seems like swappable batteries are being targeted at small bikes (scooters basically). This makes sense, because with current volume automotive battery tech the packs are just too damned big for high power bikes.

Take a look at this guy swapping a battery (pic is from the MCN article). And then consider than in ~100bhp bikes the battery is more like 50, 60 or even 100kg!

Unfortunately battery power, battery capacity and battery size are linked. You're unlikely to see a high power battery that is also small and light capacity...not for a while anyway. But you will one day not too far off.



EDIT: Just for scale, Lithium Ion batteries are currently about 500-1200W/kg power density. I.e. for every 1kg of battery you can get about 500-1200W of power out. It's a really wide spread because with EV stuff you can massively overate it for "a bit" before it overheats and catches fire. So a 50kW battery might actually be able to output more than 100kW for a few seconds.

If you have a 100kW electric motor (about 135bhp) you need a slightly more than 100kW battery to power it due to efficiency losses. So say for argument's sake that is a 105kW battery. Said batter is going to be somewhere in the range between 80kg and 200kg. You're not swapping that in a hurry! THe only real reason electric bikes are "a bit lardy" rather than "catastrophically heavy" is 'cause the engine - the electric motor - is hugely lighter than the piston engine it replaced.

[dayglo jim]

Given that a lot of riders a powering phones/comms/satnav/cameras/clothing etc through bikes have any manufacturers made any allowances for this?

[Nordboy]

Given that a lot of riders a powering phones/comms/satnav/cameras/clothing etc through bikes have any manufacturers made any allowances for this?

The way it’s going, the bikes will be charged by the phones next!

[Kneerly Down]

Given that a lot of riders a powering phones/comms/satnav/cameras/clothing etc through bikes have any manufacturers made any allowances for this?

Say that a bike does 10miles / kwh in city riding at an average 20 miles per hour and it is charging a phone via USB at 2amps...

For each mile the bike uses 100Wh of battery and the phone charger uses 0.5Wh.
So the range will be reduced by a whole nine yards [sic] for each mile travelled in charging the phone.

[Mr. Dazzle]

Given that a lot of riders a powering phones/comms/satnav/cameras/clothing etc through bikes have any manufacturers made any allowances for this?

I work for an EV motor/controller company...perhaps unsurprisingly the company founder drives an electric car.

I once pointed out to him that he'd left his headlights on in the carpark. His reply was that he'd done the maths and he figured out it would be something like 2 weeks before the lights discharged the battery hence he CBA to go turn them off.

[Cousin Jack]

I work for an EV motor/controller company...perhaps unsurprisingly the company founder drives an electric car.

I once pointed out to him that he'd left his headlights on in the carpark. His reply was that he'd done the maths and he figured out it would be something like 2 weeks before the lights discharged the battery hence he CBA to go turn them off.

Let's hope he doesn't feel the cold. LED lights may be pretty insignificant on batteries, heaters are not. A 20w light may be pretty bright, a 20w heater is not going to make much of an impact. Of course he is unlikely to leave the heater on in the car park.

[Mr. Dazzle]

Most EVs primarily use waste heat from the battery/motors/controller to heat the cabin, much like an ICE car. Even though they're massively more efficient than ICE engines they still have a couple of hundred watts of waste heat.

[Tarmacsurfer]

If you have a 100kW electric motor (about 135bhp) you need a slightly more than 100kW battery to power it due to efficiency losses. So say for argument's sake that is a 105kW battery. Said batter is going to be somewhere in the range between 80kg and 200kg. You're not swapping that in a hurry! .

Yep. Swappable batteries are only useful for small commuter bikes.
Also consider that the next generation ev bikes will have a formed battery shape (rather than a big box) and be a structural member.

[dayglo jim]

Given that a lot of riders a powering phones/comms/satnav/cameras/clothing etc through bikes have any manufacturers made any allowances for this?

Sorry guys, should have thought that one through. Still in the mindset of an ICE with a puny battery struggling with cameras, comms, AHO and the fan going crazy in the summer, had to bumpstart the capo a few times when there wasn't enough juice to crank it over.

[demographic]

On about how things are charged, some of the newest EV's have vehicle to grid charging which on just one car isn't that much use but on hundreds of thousands provides worthwhile grid level storage capabilitity.

[Mussels]

I'm not spending thousands of pounds on a battery with a decent range just to find when I need it that the leccy company has half drained it because the sun went in. They need to find a different mass storage solution.