Some costs

In my probably pointless pursuit of an electric powered replacement for my ancient Voyager, I've established some cost estimates for an electric powertrain roughly equivelent to BMW's C-Evo (long range version) - comfortably enough to produce Voyager-levels of performance, if not range. These are from local E-bicycle* enthusiasts and battery specialists.

There seem to be two routes to a custom battery pack, flat, rectangular "Apple-style" batteries that may be best for packaging but are known for exploding or catching fire if abused and smaller cylindrical, "Tesla-style/laptop" items, usually packed into 'cells', these are apparently more rocust and unlikely to combust. I'm currently focussing on these latter items. To replicate C-Evo output I'll need 2,500 of these packed into 150 cells that will wiegh 75Kgs, less than the Reliant/Guzzi powertrain. This number of batteries will cost, new, 5,400 Euro's (and probably £s by next year). I'll work up a package size optimised to fit in an FF keel area.

To this cost and wieght must be added a power management controller at £700, wieght unspecified but not huge. This is a programmable unit that can provide regen, traction control and torque limits and so on. Also a battery management system that seems to be regarded as simple and cheap. And a water-cooled motor, capable of 35Kw peak, 17 Kw continuous, at £2000.

So subject to some CAD work to establish battery packaging it's possible to buy a powertrain that will serve most prectical purposes for an FF. It'll cost about £8500, assuming a bit for the battery assembly and management, cabling, intumentation and so on (and £/Euro equivelence). The "Vehicle" end of an FF costs about £5,000 (ignoring the free labour of the enthusiast building it) which adds up to £13500, surprisingly similar to the cost of a C-Evo and an interesting insight into how much BMW must be paying for parts and labour. Not much of this can be found in scrapyards, although a frontalled C-Evo might supply a cheaper motor/rear end unit. (anyone?)

I'll publish a drawing, like previous ones, of the battery packaging in due course. This is not mysterious. The cells I've seen measure 102mm x 82mm x 70m. but need 10mm adding to the last figure to allow cooling airflow. Package 150 of these and you;ve cracked it. Meanwhile I'll have to get a ferry contract, or something, from Bozo to raise the dosh...

*In this world the term "bicycle" is used estremely flexibly, officer.

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Mental arithmatic

Instead of trying to do mental arithmatic while listening carefully to a battery specialist, himself trying to translate electronic speak into hammer action, I've gone home and used a pocket calculator. So you only need 125 cells to get 2,500 li-ion units, not 150. Doesn't make any difference to the price but highly relevent if you're trying to package the battery. Good job nobody takes any notice of this stuff...

Anybody listening?

Morning, Royce. Well, I'm paying attention. I have to admit, I didn't check your calculations. Just took them as read. I'd very much like to go the FF route, as we've recently bought an electric car, and I'm sold on the principle. However, range must still be an issue, if like me, you live in the country, and have miles and miles of tempting roads on your doorstep. My experience of our car is that you shouldn't charge it to 100% unless you're going to use it immediately, so 80% is the target for everyday. Also, the charge rate drops dramatically, once you reach 80% of battery capacity. So increased charging time also becomes a constraint. Then at the bottom end of the scale, you don't want to let the battery drop below around 10% charge, unless you're close to a KNOWN working charger. And that is forgetting that the 50Kw battery is restrained to only allow 45 or so usable units. So going back to our car, from a quoted range of 211 miles, you immediately lose 30% in day to day driving, although if planning a long journey, that would only go down to 10%, then in winter you lose another 10 - 15 % due to lower temperatures. So even if you manage to get a theoretical range of 150 miles from an eFF which would be class leading at the moment, you'd still only have a usable range of around 100 miles. More than enough for city riding / commuting, but not enough for touring / leisure. Of course battery technology appears to be progressing rapidly, so maybe in a couple of years, 150 miles of usable range will be available. At that point, I would be 100% converted.

Further work

Range is going to be the limitation for a while I think. The battery people here say that charging above 80% reduces battery life so you're on the money with your range remarks. Thay say the UK is good for EV's because it doesn't get hot enough to seriously need cooling, although some battery heating will help in mid-winter. I've done some work on the battery packaging issue, using the cells I mentioned. I'm supposed to get 125 in and so far I'm up to 102, inside the chassis I put up here recently. I'm going to do some more work on that but I doubt if I'll get to 125. 110 may be the limit and that will restrict passenger space. (2,200 individual units). I need to define motor dimensions and mess with the chassis a bit more. I'm thinking using a water cooled motor, then using the heat exchanger outlet air to heat the batteries on cold days (and me) but I can see a diesel heater being the answer there.

I guess that Aero's are the area where range can be extended, over a C-Evo etc. but that only works if you're going fast enough for it to matter. Tooling around Bristol in the 20 limit it could be brick (Bricks are of course quite good..) for aero purposes. The annoying thing is that it'll take three years to build, assuming I live that long, and the next-gen batteries will arrive around then, rendering most of this obsolete.

It's an interesting excercise though. I can understand why the E-Motorised bicycle people are focussing on recreational vehicles (Moto-cross, trials etc.) and lightweight urban scooters, it's really difficult to get enough batteries into anything longer range. The C-Evo is basically a battery box on wheels. The seat can't go any lower because of the batteries.

I think that, at the moment, instead of trying to replace something like a Voyager, it's down to acepting a limited range and designing a vehicle for a use where that isn't an issue - like Trials, commuting and so on. But with limited speed and range some FF advantages, aero efficiency, comfort, become less relevent.

eFF Analysis.

Royce, I'm sure you're correct about the type of eFF for the moment. Shorter range commuters, and lower speeds. But that experience will benefit the eventual eFF tourer, if I live that long. I'm currently wrestling with waterproofing the engine electrics on the Pete Lawrence Delta, after being left at the side of the road in torrential rain on Monday. No such problems on an eFF, I would imagine.

Cargo Scooter

The application that leaps off the page is an E-cargo scooter. Could be limited to 60 mph without loss of usability. It's also easier to package without a passenger option and would be easy to upgrade to E-Voayger spec. when better batteries arrive - due to neccessarily robust chassis and supsension details. I think I'll proceed, design-wise, on that basis.

Only snag is that it's clearly an industrial project not something Royce is going to use as retirement activity! Cue the whole sorry business of finding an industrial partner. One of the most significant things anyones said about my FF projects was "I think you're living in the wrong country" I'm not moving now, not that anyone would let me in. So I'm not going to build a prototype E-cargo scooter! But don't let that stop anyone else, younger, more naive and so on. (much richer would be a good starting point) but anyone can steal the design, but then the problem is that although they'll know what I've done, they won't know why. Could make development tricky. although for Honad it'll be 'almost simple', they'd just have to get over the corporate cowadice problem.

You should be relieved your 'water in the electrics problem' in only on the Delta, if it had been an E-FF you'd be keeping your head down in a ditch waiting for the molten battery parts to stop flying about...

Cell orientation

Make sure you stack the cells vertically. Horizontal stacking leads to more failures apparently, as the insides of the battery develop micro cracks due to bending loads.

Good tip

Thanks for that. It's very encouraging to see the accumalation of EV info. I'm relieved to note that the best packaging I've managed so far does align the individual battery units vertically.

I'd spend more time on this but right now I'm engaged in working out how to fit an earth return wire to the (Lucas)rearlight of a 1956 Norton 99 Dominator. The worst of it is that I know exactly what I did to deserve this...

E-FF range & battery costs. Some grounds for optimism?

Just a few points, 'off the cuff', so to speak, but based on real-life experience, both mine and others. One solution to the high cost of batteries is to buy second hand from crashed electric cars. I know two people who have bought a pallet-full of Nissan Leaf batteries for much, much less than £5,000. More like a quarter of that. One Leaf-full should be more than enough for the biggest FF, with several years' of use still available. I've also read about several people who've converted old Vectrix e-maxiscooters from their original NiCad to 2nd hand lithium batteries. (And new Vectrixes are now available with lithium batteries as standard; ironically, they are quite possibly the most aerodynamic, FF-ish ePTWs currently on sale, apart from the Peraves Monoracer).
And when it comes to range, remember what was achieved a whole decade ago in the RTW ZeroRace of 2010-2011. The modified ZeroRace Vectrix was capable of well over 200 miles on a charge (350kms). The winning DesignWerk ZeroTracer was capable of the same, going a lot faster (as was the X-prize-winning Peraves E-Tracer).
And Cedric Lynch told me two years ago that he thought it would be possible to cover the 870 miles from Land's End to John O'Groats on a single charge in a modern version of his streamliner.
And Terry Hershner managed to cover more than 1,000 miles in under 23 hours on a Vetterised 2012 Zero back in 2014.
And the latest 2020 Energicas have a 20kWh battery pack. I haven't got my calculator out yet, but all of the above achievements and specifications make me think that it should be possible for a Voyager-sized FF with a Cevo amount of power and weight to cover 250 miles on a single charge at a steady 70mph. Just musing. PNB

Go for it!

I bow to your knowledge of all things EV. I'm just a mech tech, with FF design experience, relying on local EV specialists and a rather good supply of used Li-ion batteries. My ancient CAD software shows that, using current battery tech, it's very difficult to fit enough batteries into a Voyager-sized FF*, for 150 mile plus range, without intruding on the (Two) passenger space or ergonomics. However, even in Bristol, several people are fitting second-hand batteries to some highly unlikely once-ICE vehicles. The bigger the vehicle the easier this is.

In a C-Evo (And similar vehicles) the rider sits on top of the battery box. In an FF the rider must sit almost among the battery box, reducing the space available. E-FF design at the lower end of the size range is just another packaging job. I have chosen to design an FF that is small, practical and cheap enough to attract enough users to actually make a difference to road vehicle efficiency (The "Ford Option"). Despite it's good looks and high specification the Mono racer is not in that category. I believe it is also the only current production E-FF.

There are no 'magic solutions' in EVs. Only battery tech is currently showing any signs of major advance. (See Tesla news release on it's new batteries a few weeks ago.) The vehicle industry seems confident that this ("Dry cell") tech will be in production in less than five years and is spending hugely to achieve that.

But this is just what I have learned so far. I salute anyone who can produce a production-standard E-FF in any part of the size range, including Arnold of course. Please feel free to do better - Someone, somewhere, should be able to do this. Why not you?

*I apologise for using the term "Voyager-size" It's obviously due updating. I'm referring to the minimum sized FF that can carry two people without compromising the standards of comfort, handling, safety and efficiency that desgin established. I very much regret that more modern examples do not exist (so I could buy one)

Seating options

Why would seating 2 people be a priority for an eFF? I know some people imagine they'd carry passengers most of the time, but even 5 seat cars do most of their miles with only the driver aboard. The cargo version seems the best option for utility for the most users. For passengers, a car seems to provide the answer.

When Royce asks "why not do it yourself?", I have the capability but right now don't have the enthusiasm to devote enough time and money to it. The main constraint is getting a road version insured in my country. Registration may also be an issue but I expect something could be done to make that happen.


I don't think utilisation rates are very relevent in the market place. I have use of a five-seat car which also usually carries one or two people. But it was chosen because it could carry five people and quite a lot of freight when that was needed. Which it has been on many occasions. I also have use of a 2.5 tonne Transit, that rarely carries 2.5 tonnes,. but is extremely usefull when it does. And so it is with PTWs. FJ rarely carries two people, but can carry 80Kgs of freight instead, quite valuable in Bristol, about to initiate Clean Air Zones penalising all deisels but not PTWs. People buy utility. Buying a single seat PTW is a commitment to never carrying a passenger - unlikely to be a selling point, especially with young people.

The Cargo option, although a potentially large market, is a speed and range limited vehicle, not the full spectrum FF of the type represented by FJ. This may be possible - I haven't finished packaging yet - and certainly will be when dry cells arrive. Such a vehicle fully exploits the FF advantages and maximises attraction to the market. I do not intend to be a delivery rider but I do wish to replace FJ with a modern version. That is my design criteria.

You make a good point about the difficulty of registering a single vehicle under EU single vehicle approval proceedures, although it is possible. It's a lot easier in England where the state is disinterested and, post-brexit, is allowing a reversion to the 1986 Construction and Use Regulations - as far as I can make out...

It's good that you have the capability to make an E-FF and not surprising that you lack the enthusiasm. You share the company of Honad, Ford and Piaggio in that respect (among many others).

FabrizioCross's picture

Electric FF thoughts.

Hi Royce, I've been working on a recumbent e-bike design for some time (, and while the power limits are different, I do have a few thoughts to share.Trulli

1. Batteries- It is true that charging to 85% of rated capacity will double the lifespan of you pack. This is because in the early days of Lithium batteries the manufactures agreed on 4.2 volts per cell as fully charged, even though it was not ideal for the cell. The capacities were lower then and they needed to get as much power per cell as they could. Now that capacities are so much better we don't need to do this to our battery cells. I run a programmable charger that lets me charge to 85% most of the time but if I have a longer trip coming up I charge to 100%.

2. More on Batteries. the two dominant cell formats right now are 18650's and 2170's which are respectively 18mm X 65mm and 21mm X 70mm. The 18650 was the dominant size but the 2170 is slightly larger and has much greater capacity. The downside of the 2170 is that with the larger size it does not shed heat as well. Heat is the real killer on any battery pack. I don't build packs, I simply order pre-made packs with BMS (battery management system) boards built in. My bike is running on a 72 volt 40 amp-hour pack. This gives it a top speed of 65 kph. For Motorbike speeds I would suggest that a 110 volt pack would be the minimum.

3 Motor. Direct Drive Hub motors make a lot of sense for a street machine. They support regenerative braking, are mechanically simple, require no complicated chain-line, and leave all the space on the chassis for batteries and controller. Most Direct Drive Hub motors are run by 3 phase AC controllers that are commonly available.

Enertrack make one of the more popular conversion motors.

QS motor is also popular with the conversion crowd.

One of the cool things about hub motors is that they make an dual-wheel-drive system easy. I think Dual-wheel drive would be especially advantageous on an FF bike.

A good place to check out what the Electric Moto crowd is up to is at

Good stuff

Good the hear from Vehicle E-specialists. I've learned so much about E-power recently I understand at least half of this! I;m pretty sure I'm looking at using the 18650 batteries, put together locally into packa of 20. These are used, tested, batteries initially recovered from laptops but now apparanetly joined by ex-vehicle batteries. Being enthusiastically used by E-bicycle er... maniacs. I see 'dry cell' tech coming over the horizon, that may solve the basic packaging problem, but not the cost, at least intially.

Hub motors are very interesting for the reasons you mention, better space utilisation and two wheel drive. However, unsprung weight is an issue and also power output, although twinning helps with that. As a vehicle engineer I'm also a bit worried about power management, there needs to be a power split that's managed and also measures to prevent harmonic variation in power delivery. This is a serious issue that can cause loss of control and killed John Cooper when he lost control of a double engined Mini many years ago. All solvable, except perhaps weight. There are some nice hub motors being shown (e.g. I've also been pointed at as the 'conventional' motor I need, although I'd prefer the water cooled version so I can use that for cockpit heating (An Essential feature!)

It's interesting that the AC/DC debate continues. A lecture on this would be informative for simple vehicle engineers like me...

FabrizioCross's picture

AC vs DC

I think the AC vs DC debate is pretty much done. Now that AC motor control is affordable there are not many good reasons to go with DC. I can say from personal experience, having used both, that AC is far superior. It is easier to integrate, offers smaller components, and has higher efficiency. Here's a simple article.

"My ancient CAD software

"My ancient CAD software shows that, using current battery tech, it's very difficult to fit enough batteries into a Voyager-sized FF*, for 150 mile plus range, without intruding on the (Two) passenger space or ergonomics."

I sold off my new motor and controller (comparable to a several year-old Zero) and gave up on my e-FF project because 1) with only designing for a solo rider but for the 150-200 mile highway range I ended up with batteries below, in front and behind the rider (and a fairly heavy vehicle), and 2) the batteries that could be had that might work for the range and form factor desired were not even close to being in what I thought of as a reasonable budget.

Batteries seem to come in big rectangular blocks that don't fit well into a low FF vehicle that leans into the corners and so has ground clearance as an issue, or they come in small cylinders (which are actually just the pouch cells rolled and stuffed in a can) that open up pack shapes but will need thousands spot-welded together into a pack. I can make a wiring harness, but I know my limits and I wasn't going to deal with trying to DIY a 100V and 20+ kWh pack, and buying in a custom pack makes instead buying a couple of donor ICE bikes for projects look pretty appealing.

I like the idea of e-power, and if I was interested in making an e-FF with a 50 mile range it could have been a doable project. But I do have range anxiety, even if most of my rides are under 100 miles, and it looks like batteries from a decade or two in the future are what were needed.

Batteries and PTW packaging

I think Michael Moore and I are on the same page, as old-school vehicle techs, somewhat appalled at the voltages and amperages needed and discouraged by the size of appropriate battery packs. But E-power is the future (for now) and we have to accept sticking with some ancient heat-engined vehicle, or try and get a handle on this emerging tech. Two trends seem to be emerging. On one hand there are the bicycle maniacs putting together DIY systems of relatively low power and voltages in mainly, I think, DC systems. This seems quite do-able but isn't up to FF power specs. On the other hand there are car-scale projects, using AC systems and more or less stock car motors and battery packs, running at hundreds of volts and amps. For FFs the power outputs are way higher than needed for an FF and the motors far too big.

I think Michael is right that a motorcycle power train is best in terms of size and rating, although that gets us back to the problem of packaging a relayively large battery pack and the alarming task of assembling and wiring up a box that can not only kill but do a decent roast in the process. Motorcycle manufacturers also fall into the gap between bicycles and cars, hence the plethora of lightwwight, short range motorcycles (as seen on EMN) and the rarity of full-size E-motorcycles that could be FF Donors. The C-Evo is a perfect example of the difficulty with a battery box that cannot be fitted to an FF, tightly integrated into a motor/controller system. The rarity means that suitable donors are scarce and any that turn up in scrapyards are instantly bought. The Kart race motor linked to above is an interesting alternative.

All these difficulties can, as usual, be solved by the simple application of money. Anyone with lots of that can stop reading this thread and get on with spending some. As a proponent of the Frank Williams approach (No money? do it any way) I can only continue to examine the packaging of second-hand batteries, while studying the motor market - in case something turns up...

Following the mention of Nissan Leaf batteries I have been sent this link with a comment that the battery tech used has a shorter life than current tech.

FabrizioCross's picture

more thoughts

Hi Royce, the bike maniacs are using AC systems as well. All batteries are DC of course, but the majority of bicycle hub motors and mid-drive systems are using AC motor control.

Here's what I think would be an ideal hub motor for an FF Motorbike.

Rated power:10KW or 12KW

Wheel size: 6.0×17

Matching tire:180/70-17 to 220/70-17

Max. Speed: 140kmph

Required rear fork width: 230mm
QSMOTOR 12000W 17inch In-Wheel Hub Motor with 6.0×17 Rim