6,000km off-road charity ride on an electric dirt bike...

[desertedev]

Hi all,

I've been working on the electric conversion of a dirt bike (Honda CRF450) for the last couple of years and have just returned from a really encouraging test trip in the Sahara where the bike performed well with good range and more than enough power (around 60kW) to tackle the big dunes.

After some further modifications, I'm planning to take the bike on a new challenge to trace the 6,000km Dakar rally route in Argentina and Chile with the help of my brothers. We'll be recharging from a portable solar array packed on the bike so that the ride itself is essentially emission-free and more importantly not constrained to the next fuel stop!

https://www.desertedev.com/wp-content/gallery/sahara-test-trip/p1060059b.jpg

My hope, if we're successful, is to give the electric vehicle's reputation a bit of a boost, and the expedition will also be a great opportunity to raise money for environmental charities (we've chosen Friends of the Earth and WWF).

The project has been self-funded so far but we now need help so that we can make it to the starting line early next year as planned! It would be great to hear people's feedback and comments on the whole thing - and if you'd like to contribute to the project, check out our crowd-funding campaign. This is to help with the purchase of the 1.5kW solar array and a much-needed battery upgrade. Any money that can be recouped from the bike and the kit purchased for the trip will be donated.

A massive thanks to Korn who’s kindly granted his permission for me to post on here and if you're after more info, we also have a blog...

[SamWise72]

Epic mission! How long is the recharge time from the solar array under desert conditions?

[Ayrton]

Looks good.
I really dont think awareness of electric bikes is needed. Bikes use much less fuel than cars already and electric vehicle technology is not where it needs to be at to be a good alternative to engined bikes or cars.
Good luck though

[SamWise72]

[Ayrton]

[desertedev]

[desertedev]

[SamWise72]

[Irn-Bru]

Interesting stuff. Have you taken into account that the panels will probably get covered in sand often? Probably will need to wash them frequently.
____________________
KTM 990 SMT & Suzuki DR-Z 400 SM

[Robby]

I'm interested in the build - if you've got that sort of endurance and performance, then the tech is good enough for me to build a commuter that isn't a shitty scooter with a 20 mile range and a 25mph top speed.

Do you have the spec and the build documented anywhere? One of my rolling chassis needs to played with.

[chris-red]

[Ayrton]

[desertedev]

[desertedev]

[desertedev]

[tahrey]

[tahrey]

Also...

1/ Manufacturers not putting money into it ... erm, ok, are we talking just bikes, or in general? The car manufacturers are starting to get into it big time now as there appears to be both incentives and some kind of consumer demand. The chinese are hot for electric bikes, and there are even some faster models (at least one of which is American... Vector I think it was?) with pretty good performance but non-ludicrous price tags. Well, as non-ludicrous as £11k can be for a scooter with the performance and range of a 400cc with a 5-litre tank, anyway. And then there's the Renault Twizy, which a mate verrrrry nearly bought (he was put off by the poor weather proofing ), and whose technology could translate very nicely into 2-wheelers with a bit of further refinement and repackaging. 17hp continuous (limited by law, not physics/engineering) with enough stored energy to punt along in a 400kg aerodynamic disasterpiece at 50mph for more than 40 miles, and a purchase cost under £8k? That'll do for a leccy bike. And people are actually buying the 4-wheelers...

2/ The "oil companies buying up electric innovators" thing. Ehhh... I don't believe this one so much any more. It used to be a fairly regularly trotted-out conspiracy theory, that may have held some weight up til the mid-late 90s. Back then electric power and renewables was a threat to their business. Now a lack of reserves, fewer miles being travelled, energy efficiency drives and so forth are the bigger threat, whereas renewables and electricity generation - along with the sale of things that use electricity! - are a potentially huge moneyspinner that's well worth getting on board with. Not least because of the fat government grants and contracts on offer. So you have companies like BP and the like investing heavily in renewable energy projects, infrastructure and companies. If you can't beat em, join em. And you can bet that they're not being purely philanthropic - it'll be a dragon's den setup. They'll get a nice cut of the profits. And who's to say that the ultimate payback from feeding solar power to a bunch of 50kW electric motors doesn't ultimately end up generating a bigger figure on their balance sheet than prospecting for, digging up, transporting, refining, distributing and selling crude oil products to be put in loads of 50kW ICEs? Even if it's cheaper at point of sale, if production is also way cheaper, then that's a tick in the box as far as the accountants and shareholders are concerned.

3/ Desertedev ... I love that you're feeding us some real world figures here. Are you genuinely getting as much as 300km of travel per day off the solar cells alone? I mean, adjusting for the much reduced insolation that we'd see in the UK, and put into the context of what distance you can cover after five minutes of filling up at a regular pump (I could get about 400k with care), it's not brilliant, but damn if it isn't a really good start. It's certainly way better than I expected. Certainly, if I could get an average of 35k's of range into a bike's batteries every day off a panel (maybe stick it on my garage roof and cache the charge in some old lead-acids?), depleting the average level over the course of a week and topping up on weekends, that'd do just fine for getting to and from work. Especially if it could be had at a decent price.

1.25kW of charge capacity sounds rather low for that kind of distance though, what sort of speeds and ride times are you doing / expecting? Is the bike sat still all day and then you ride at dusk / at night? The pack carried on a jeep? Or you just ride til it's exhausted and set up camp until it's good to go again, getting decent range even without capturing something close to 100% of the available sunlight?

(That's 1.7 horsepower equivalent ... So one hour of charging gets you the equivalent of about ... 14 miles? 22.5k? IE a half hour of going flat out on a 50cc scooter... 300 / 22.5 = 13 hours 20 mins ... erm?
74V x 40Ah = just under 3kWh ... ~2.5h to full with a fairly aggressive profile ... then, say, 70 minutes of riding at 45km? Or about 53km per 2.5h charge... 21 km/h average... 14h to do 300k, though possibly a little less because of "fencepost" error? Sort-of doable in summer, anyway, I guess? Need to find some way of riding with the cells extended and improve your overall range by at least a third!
You said that thing had a 60kW motor by the way? Enough to burn through the full charge in 3 minutes at full chat? ... I'd be terrified if my laptop battery did that! Mainly because it would be dumping a good kilowatt through itself, the computer, and my clothes/skin, catching fire in short order. How do you stop them from overheating... in the desert...?!)

nb i haven't got to look at the blog yet

EDIT... mathing that vs my garage-top solar cell idea...

35km of range per day ... vs 53km in 2.5 hours / at 1.25kW ... that would collect all of 2kWh a day, equivalent to 1h 40 of desert sun. Which I guess is just about plausible. Though in winter, with about 8 hours of usable light, and said light already being weaker and overcast... would illumination at 21% of the strength of the Moroccan desert maybe even be expecting too much? (Eh, just double up on the cells, there's enough room up there...)

53km range on the "tank" (as commuting would probably exert a similar overall load to a steady 45k cruise, with regen braking etc)... if I'm doing about a 42k round trip, that doesn't leave much leeway :-/

For a horrible week in mid December:
Day 1... start fully charged. 53km range. Come home with 11km left. Add 35km onto that from the day's charging.

Day 2... start with 46km range... 7 less than before. Come home with 4km left. Add 35km onto that from the day's charging.

Day 3... start with 39km range. Conk out 3km from home and push it that last stretch (or go onto low-power settings 6km out and limp home). Add 35km from the day's charging.

Day 4... start with 35km range. Conk out 7km from home (or go onto low power settings 13km out, and limp to a halt 4km out). Abandon bike in a not particularly salubrious location and get the bus... or push it 2.5 miles, taking an extra hour.

Day 5... call in sick. Get bus back to dodgy neighbourhood. Pick up bike if it's still there. Take 2 hours pushing it home. Curse a lot.
(Or: with 35km of normal range in the "tank", ride to work slightly more carefully, turn up a bit late, then deliberately put it on low power to get home with, and have it blip out just before cresting the final hill... push it a few yards then coast).

Day 6... Start with 35km. Start charging directly off the panels instead of the storage battery. Fully charged by about midday (as it's GMT). Go christmas shopping, keeping very close eye on the range. Return with about 5km remaining. Dump the remaining 17km charge into it.

Day 7... Start with 22km. Have a little run to the supermarket that's 2km away. Get back with 18km remaining. Just-about fully charge the pack off the 35km the cells have collected.

So, hmm. I guess I'd have to have something with a slightly better daily rate (all joking aside I've probably estimated that daily generation figure a bit low? what's the relative insolation of an overcast december day in Britain vs a clear summer's day in north Africa?) - extra panels etc - and a larger storage pack in the garage to help cover the leaner times. Plus a larger battery on the bike. After all, the cells could actually generate enough power to cover 5 days of commuting plus 29km in reserve, it's just that the mobile pack bottoms out too soon. 70km (+33%) would just about cover it I think? Being almost totally zapped by friday evening, but then getting enough over the next two days to recover.

Or of course, just 20% more generation per day (25% of desert rate instead of 21) would keep the pack at a stable charge level. 10% more would probably prevent it running out before the week was up. That's not much more solar panel to buy for a permanent install. And when all else fails, some kind of mains feed could be run out to it on an extension lead when parked at work to shove an extra hour at into it at a battery-friendly 625W or so. Electric cars manage about 200Wh/mile don't they? (Or per km?) So that would be enough to cover a 3-4km deficit at worst and only cost me 10p put in the petty cash tin...

Iiiiinteresting.

How much did you say it cost again?

[desertedev]

Sorry for the huge delay in getting back! Been away with no comms.

@Tahrey

Thanks for detailed reply! Bloody impressed. You're right that there are manufacturers out there that are starting to funnel money into EV's; both cars and bikes. Typically auto tech applied to bikes has lagged several years behind cars (e.g. most road bikes didn't see injection until around '08). EV tech tends to be a different story though as bikes are quite an appropriate platform for several reasons, in particular the limited ancillaries (no A/C and heating issues which tends to kill EV range). Having said this, I'd make the assumption (rightly or wrongly) that the majority of OEMs are heavily subsidised by government research and enviro grants (as is the one I contract for) to offset the risk of mass-producing a vehicle with a less certain and relatively limited consumer demand. Very difficult to say really without all the stats in front of you but that's my impression. Reg the Renault Twizy, for me this vehicle tends to perpetuate the EV stereotype really. Quite impractical (not in relation to the powertrain but the weather-proofing issue you've mentioned) and quirky styling. Price aside, I imagine something like the Smart Electric Drive trialled in London a couple of years ago and the Tesla range to be a step in the right direction.

Ok, the figures for the bike! They're based on the only testing we've managed with the bike so far which includes off-road rides in the UK and desert testing in the Sahara a few months ago (the bike isn't road registered as yet). The majority of the data are from the various types of terrain we encountered in the Sahara including firm rocky plains, soft sand trails, wadis and steep dunes typically running at approx 30-40mph. This has been the most important for us to quantify as there's understandably very limited information of rolling resistance in these conditions. We back-calculated an approx rolling resistance and then scaled to typical coeffs for hard tarmac. Given we were more interested in the worst case, I wouldn't be surprised if there's some error in there for the on-road approximation. I'll update when we've registered the bike and collected some reliable data.

As far as the ride itself, the intention is to stow a 1.2-1.5kW array on the bike itself. Obviously we'd like to go bigger to improve charge times but we're limited as to what we can realistically package. With a 1.5kW array we should be able to maintain a 0.5C charge and be done within a couple of hours (for the 40Ah pack charging from a min of 3.5V). We're toying with the idea of upgrading to 80Ah if we think we can get two charges done within one day although this would be a stretch. All numbers are for solar insolation in the Sahara although we're expecting similar (likely slightly degraded) in South America. In this case we're expecting a range from our numbers of approx 30-40 miles from each full charge in our worst case terrain depending on riding style (rolling resistance decreases significantly if you're riding well and can stay on top of the sand). These numbers are based on maintaining around 30mph over undulating small, medium dunes w/o regen (regen's of little use on such soft surfaces). Unfortunately running with the arrays extended isn't an option. When they're extended they take up a considerable area which would be fairly impractical to ride with. Maybe one day when the efficiencies are higher! Much higher

Reg the Agnis, 60kW is the rated peak of the system. We tend to run it at closer to 50kW which is more than enough and only really used in short bursts to get back up to speed and back on top of the sand. Overheating has been a problem as we've had to filter the intake air heavily. We're looking to redesign the intake to minimise the need for filtration and improve the airlfow. Work in progress at the moment!

Hope that answers a couple of your questions! I'll post again soon when we've confirmed so more of the details. As for the cost of all this so far (bike, gear, test trip), I try not to think about it too much as I start to tear up a little. Ballpark would be over 30k though...

[tahrey]

Very cool you've obviously put the yards in on this one!

Not much to add at this point other than waiting to see how you guys do - except that in a strange case of synchronicity I went into a local independent-ish dealer and saw a couple of electric bikes they had on display...

...and ended up taking a handful of bumf home, as I was thoroughly impressed, and although they're still rather out of my price range, they definitely seem to represent a bright future. I'll have to try scanning some of it up and uploading.

Company name "Zero" I think? Had a roadster and an enduro type, though they seemed to largely share the same bits. Just a big ass leccy motor in the rough place you'd expect the crank of a normal engine to be and a toothed belt running to a pretty big rear sprocket. Other than that, a lack of clutch/gear pedal, and an added "eco"/"sport" switch, they looked pretty normal.

85mph top speed, variable ranges depending on price point but all reasonably practical, mediocre but certainly not terrible charge times (including a much shorter ~80% quickcharge), general performance suggestive of roughly 250-400cc equivalence. Prices starting around £7k with the display models being a quid under £10k (breaking that crucial 5-figure barrier).

The two killer items on the list however were that you could apparently ride them just with a CBT (maybe the eco switch caps the output at 14hp when open-circuit and you can only have it wired in after passing your test?)... and that the battery pack was good for 80% of original capacity to at least 150,000 miles.

Yes, 150k miles. 250k for the more expensive, extended-range one. And it looked like at least some of that was guaranteed. I think there might have been a temporal guarantee as well but my brain was overridden by that headline figure.

It's the sort of thing to make you wonder about taking out a loan, because you wouldn't think too much of buying a £1000 bike that you'd ride for 15,000 miles whilst making a solid killing on the fuel and maintenance costs.

Assuming it's not BS of course