Homemade Royal Enfield Electric Bike has done 13,600 km

Fred Spaven, a mechanical engineer from the United Kingdom with a passion for all things automotive, especially anything unusual – built a ‘Charging Bullet’ – restored from a 1961 make 350 Bullet – a model made at the Royal Enfield Redditch factory in its final years.

Spaven is no stranger to adventure travel, having previously taken a Skoda to Mongolia, a BSA Bantam to south Italy, a train to Singapore and circumnavigated Yorkshire in a Reliant Robin. On his E-Bullet, Spaven travelled the entire length of Britain from Lands End to John O’Groats. Following a career in superconductivity research, Spaven decided to follow his real interest to set up Spaven Engineering and specialise in the restoration and modification of classic cars and motorcycles. 

Enamoured by the recent explosion of battery power and having successfully curated a tankless ‘Charging’ Bullet, Spaven is doing a PhD on electric motorcycles from the University of London. This week ElectricVehicleWeb.in caught up with Fred on his journey on building the Charging Bullet and how he achieved it. 

What are you up to nowadays?

I am doing a PhD from University College London, which is investigating how to develop a long-range electric motorcycles.

EVs have been around for a while now, but they are limited to urban transport because of short ranges and often low speed due to the battery capacity. There has been a lot of development in battery technology. The bike is fundamentally limited by the physical size of the rider, you can only put so much battery on a bike. One can’t put a 200-kilo battery that car manufacturers can. 

Fred Spaven and electric Royal Enfield bike

I am trying to improve the efficiency of the bike rather than work on brute force or battery size. The aim is to work on a longer range keeping in mind the price of the vehicle. I am trying to develop a two wheeler that you can do your holiday on or the one that can ride 500 miles (800 km) in a day with the support of a charging network.

Tell us about your Royal Enfield project

I have been commuting to work on my old BSA for years. I love classic bikes, and I travel everywhere on my old bike. As I was doing 35-40 mile (56-64 km) roundtrip, it was very predictable; and being environmentally conscious, I thought it was a perfect opportunity to do an electric bike. 

A curious engineer in me wanted to explore something new, and I knew it was doable. I had partly restored a 1961 Indian Enfield bullet. I had rebuilt the frame and a lot outside of it, but the engine and gearbox were absolutely kaput. So I thought of making this nice historic bike a case apart by turning it into an electric vehicle. After a lot of research and scouting around, I put in 12 Nissan leaf battery module, a brushed motor, at a time when everything has become brushless.

While I was getting started on the project, a friend of mine – an independent filmmaker – wanted to make a documentary about something interesting. So a film on the making of the bike in a shed and being used for office commute would be too boring and run of the mill. So we put our heads together, did a bit of googling and decided to do the entire length of Britain from Lands End to John O’Groats.

So we agreed to make a film. We took it up as a challenge. It was towards the end of 2017, and we took off. The bike did 1400-1500 mile journey without blinking – without testing, we just did it straight with the brand new thing. The bike is a testament to how there is a rugged simplicity of electric.

'Charging Bullet' electric Royal Enfield Bullet conversion battery and motor

Along the way, we met a lot of British companies that were developing different clean transport technologies. We met a bus company in Bristol running on the biogas, as they found batteries were too expensive, we saw some electric race bikes, which were phenomenal, from Notting University, a solar car from, Durham University, a whole range of different transport solutions, all of which were already starting to make the world a greener place.

We made the film, it was great. It was nominated for the best independent film at the 2020 International Motorsports Film Awards, I believe. So we are waiting to see if we’ve won a prize for that.

These things take time, it turns out that documentary making is not a quick process. Post that, I rode to work on my bike, and I went back to what I was doing at the time, which was restoring historic racing cars. And I still get a little bit of work, but it wasn’t enough anymore. I caught the electric vehicle bug. 

So, I hooked up with a colleague of mine, who is a lecturer at University College London, who recommended me to research on electric bikes properly. I started a year ago, I’m now a year into my PhD. 

I’m researching, how you can get a 100 to 200-kilo motorbike, you cant fill them with batteries, and the reasons one is riding a 100-200 kilo motorbike in the first place, is that they probably can’t afford a Tesla. You know there are a lot of fundamental issues here. At some point, once or twice a year, you want to go and visit families in another city. You’ll want to ride off into the mountains, for a weeks’ camping, you want to do something that is beyond your 30-40 miles (48-64 km) a day, which the electric bikes can do now. So, you need this machine to be able to do long distances.

'Charging Bullet' electric Royal Enfield Bullet conversion speedometer

Even the tiniest little petrol moped, you can just keep filling in the fuel and you can do hundreds of miles, and people do. And so we need to be able to get these electric vehicles to do these occasional journeys.

Cars are managed through very energy-intensive, expensive infrastructure and very big, heavy batteries; they have managed to overcome this hurdle. 20 years ago, you couldn’t go on holiday, but now you can on an electric car. We just need to move bikes into that world as well.

Take us through the engineering, build and sourcing process of the Royal Enfield Electric Bike.

It took a long time: six months of planning and talking to people and another six months to build the bike in the evenings and on the weekends.

The fundamental thing is the batteries and the massive energy storage issues with it. You get about 10 kWh of energy in every litre of petrol. You have a massive energy deficit when you compare it with petrol bikes. The first thing I looked at is, how many batteries I can squeeze in and what kind of batteries to use. It was quite an experience. I took a lot of advice from people who have done similar projects. I had not worked on batteries at all, and so I went for the safest option of Nissan Leaf battery modules.

They effectively come as a big seven-volt battery with two screw terminals, and that’s prepackaged in a slightly flimsy aluminium can, a little bit like a sardine tin, but it is the size of a laptop. Because they’re big, you can just stack them up, and it works. Then you manage them with a battery management system which stops it from catching fire, something a few cars have famously done!

I worked on how many of those could fit in and that essentially set voltage, because of the prepackaging of the batteries, you can only get a certain voltage out of a certain quantity of them. So there’s a lot of flexible ways of doing it since I was inexperienced. This is my first go. That got me to about a 50-volt system which suited. Just not far from here, at Bicester, is the Saietta Motor Company, who manufactures the current iteration of the world-famous Lynch motors, which are permanent magnet brushed motors, which were originally designed by Cedric Lynch in the 1970s.

They are excellent, they’re an old design now, but they’re very torque-dense, which is, essentially what you need if you’re running a single chain drive. Because you can only get so many reductions away – in the region of about eight to one is your limit. So instead of a gearbox and a primary chain and final chain that you’d have with a petrol engine, you got to do all in one volt, to save on transmission losses. 

'Charging Bullet' electric Royal Enfield Bullet conversion rear

So it’s a very good torque-dense motor, and it’s been used in the early Isle of Man TT Zero races in 2009-2010. So it’s up there with the modern, brushless stuff, and so I went with that option. And then you can drive that with a very basic motor controller, which I sourced from Kelly Controls, an American company.

That’s on the electrical side of it. On the mechanical front, I wanted to keep as much of Enfield as I could. I’m an Old Bike person, and that was how I got into it. So, all I did on the bike was a full restoration, and so, while there’s a lot of new stuff, it is all based on the Enfield.

All I did was essentially drop out the engine and gearbox and remove the tank, and then fabricate a steel subframe that would hold the batteries pretty much where the engine was. So you get the weight low and forward on the bike, which is where you need it for good handling. And then where the gearbox went, was a mounting to the motor so that the motor’s sprocket is basically where the gearbox outputs marking would have been. A little bit off on that was annoying. I know I miscalculated slightly; it’s got a chain tensioner on it, and we’ll live with that.

I didn’t cut the frame at all, which in theory is what you have to do for the UK laws. A lot of people do cut frames and get away with it. I chose not to. The steel subframe holds all of the electrical components that bolts to the engine mounts and the fuel tank mounts, and it just replaces the internal combustion unit. It looks a little bit odd without a tank; some people don’t like it, but I quite do, and that’s just styling at the end of the day.

It’s sort of simpler in that sense. It’s just a big steel box and because it picks up the engine mounts as well as the fuel tank mounts higher up, I haven’t calculated and think tested anything, but it feels like it’s definitely the frame up as well, which is quite nice. 

So it’s an Enfield it’s got the Indian front brake apart from that it is very, very standard.

'Charging Bullet' electric Royal Enfield Bullet conversion battery and motor

Could you share some specifications of your electric motorcycle?

The battery pack is about 6 kWh nominal and which is what people quote. The batteries are 10-year-old now, because they came from a second-hand Nissan, three or four years ago, and I’ve tested them. I’ve recorded them doing 4.8 kWh, which is fine for a range of 50 to 60 miles or 100 km for a round number and you can do more, I have done more.

Speed-wise, I’ve got it geared down to only do about 45 mph (72 km/h) to give me just better performance up hills, and it will do 55-60 mph (88.5 to 96.5 km/h) quite happily. So I sized it to be similar power to the 350 Bullet, which is what it used to be. 

I have found that the most of it does get a bit hot. So it’s an air cooled motor and it is shoved in behind the batteries. I think it can give up to approximately 16 kW peak, but it’s a bit dodgy to use up because of the heating. So I’ve got it set to about half until I work out how to improve on that.

And what I need to do next is replace it with a 20 kW brushless water-cooled motor, which will eliminate brush losses, which should give me even more range. Moreover, I can utilise the full 20 kW that the batteries can actually produce. So, it is time to lose the brush motor now!

How much did you spend on the project?

I spent about a year of my life on it and a lot of research and about GBP 5000 (Rs 4.7 lakh) to build. I would say obviously an awful lot of labour as well. Having learned from doing it, I could do it cheaper now, but you know how things are like the first time. You make mistakes, and you go with what you’ve got. So, I was amazed to some degree that it worked.

It still amazes me now, when I built it, everything overruns, and I had time to do 100 or 150 miles of testing before we set off on Lands End – John O’Groats trip. Because of filming commitments, we were tied to dates. 

It probably took about a day and a half before I just started treating it like a washing machine. I just turn it on and use it and then turn it off again. I just stopped thinking that it just didn’t miss a beat. It was incredible. The old petrol one probably would have not done it.

How much have you ridden on this, and what about the homologation post the electric transplant?

I have done about 8,500 miles (13,679 km) on it. I use it for work every day, and it adds up fast. The 8,500 miles includes 1,500 miles (2,414 km) of the original Lands End – John O’Groats trip. I ride about 100 miles (161 km) a week, pretty much every week. I’m a pretty hardy motorcyclist from England, so I usually miss two or three months over winter, but apart from that, I am out in the nights every day.

'Charging Bullet' electric Royal Enfield Bullet conversion and Fred Spaven

The homologation is greatly simplified by using an existing vehicle. By keeping everything Royal Enfield apart from drivetrain, I got to keep my registration. Essentially, it’s regarded by the DVLA, the UK’s vehicle licensing authority.

It is regarded as just being an engine swap. So it’s the same as if I did the diesel conversions that are fairly popular or put a Yamaha engine on it. They treat it exactly the same as if I’d done that. So it kept its registration, it also greatly simplified insurance because it allowed me to use classic insurance companies, who are usually a lot more tolerant of modifications. 

So that was very intentional for us and our bike works in the British legal system.

Images in the story were supplied by Fred Spaven.

If you are a fan of Royal Enfield then check out the Royal Enfield ‘Photon’ electric motorcycle by Electric Classic Cars and the Royal Enfield electric Tribute by Kerala-based Hound Electric.