Mid-mount Hubmonster Madass

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Ohbse
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Mid-mount Hubmonster Madass

Post by Ohbse » Feb 14, 2016 2:03 am

My new build is something a little further towards a 'proper' moto. Given that I'm riding faster than traffic on a daily basis, wearing full moto gear - I think I should be somewhat more 'legit' than my current bike (DH Comp, Cromotor, 1.8kwh, Adaptto Max-E)

The beginning:

I started by laying out some requirements:

1. Power - specific power to weight at least 50% superior to my current bike (8kw/42kg+70kg rider = 112kg)
2. Range - real 100km without anxiety
3. Speed - Can maintain 100km/h without much stress or any overheating (though not for 100km)
4. Road registered - preferably as a moped

In NZ the legal definition of a moped is essentially only restricted to a maximum speed of 50km/h and maximum of 50cc displacement where applicable. In the past there was also a maximum power output of 2kw however this was removed as any quality 2 stroke 50cc moped had been over that power figure for 20 years. People also figured out that quicker acceleration to the same top speed is actually significantly safer as there's a lot less angry overtaking occurring. I can be a legal moped by limiting my top speed, doesn't matter how much power I use on my way there - cool. I will of course have a defeat for this limit built in for 'off-road use only'.

I investigated what it would take to scratch build a bike and then register it as a moped. There are pretty extensive requirements for scratch built vehicles and I was looking at $2k+ in paperwork alone to have it certified by an appropriate engineer and eventually put on the road. I couldn't find any examples of anyone actually completing the process and there was no guarantee of success.

I started to look into donor bikes that were already registered, unfortunately I found that due to various fraud attempts it's very difficult to re-register a motorcycle as a moped as people would frequently do this to avoid higher registration costs. In short, I needed to buy something that was already registered as a moped. This narrowed the scope for donor vehicles considerably, leaving only a handful of older 50cc sport bikes which tended to be quite rare and sought after when they did come up, a variety of 50cc scooters of varying quality and one stand out, very affordable option - the Sachs Madass 50.

I went and test rode one of these brand new and was impressed with the solid, overbuilt frame/fork, huge brakes (for a 50cc), quirky styling and minimalist configuration that lent itself well to engine conversions. I was hugely unimpressed with the engine, clutch, gearbox and throttle - thankfully all these are going in the bin. I found one for sale second hand with ~1000km on the clock and only a few months old for $2k and bought it. Now I'm committed.
Original Madass.jpg

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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Feb 14, 2016 2:55 am

The Drive-train

Motor

To meet my requirements for speed and power I need a peak of 20kw power and a wide range of speed. I evaluated a large number of both hub motor and mid mount options. Hub motor was appealing as it would be simple, packaging the battery etc would be easy. Mid mount offers superior efficiency, lighter weight with the downsides of chain maintenance and noise.

The challenge to reach my goals was not making the power, it was cost - many of the motors capable of this 20kw figure required elaborate, expensive and very physically large controllers. John in CR's Hubmonster stood out for affordability, compatibility with relatively cheap/compact controllers (despite requiring two) but primarily it was attractive for out and out performance. Due to the high KV it's a challenge to use this motor in its ideal efficiency range in wheel, requiring quite a small rolling stock. By pulling it out of the wheel it allows me to volt up and gear down, delivering substantially more thrust at increased frequency. Plus I can vary this gearing with a relatively simple sprocket change.

With an effective phase to phase resistance of 0.016ohm, low no-load losses and general high quality construction this motor should actually be capable of substantially higher peaks than my 20kw goal, but I'm going to take this one step at a time :)

The plan is to mount a conventional sprocket using the 3 bolt disk brake flange on the motor. From my brief mockups so far the chain line actually ends up superior to the original Madass due to the increased front sprocket size giving additional chain clearance to the swing arm. Motor positioning is going to be approximately in the original location of the 50cc's crank case, as tight to the top tube and as far rearward as feasible. The motor will be mounted in a tubular fabricated subframe that picks up on the original motor/swingarm mounts on the main tube. Motor axle will be fully captured in 10mm+ thick torque plates. To the bottom of this structure I will mount the foot pegs and kick stand as well - these actually bolt to the bottom of the engine on the stock bike. It looks like I will be able to get these in the original location/height within a few millimeters.

Controllers

I have purchased a pair of Sabvoton 100v100a capable units from zombiess. These are cheap, generally regarded to be reliable and should be capable of the ~10kw each I require to hit my performance goals. They are NOT well supported by the manufacturer and I fully expect a lot of pissing about with frustrating chinese software before I get these working as expected. These should run up to 120v and apparently deliver 100a and up to 350a phase current.

Long term I will likely replace these with something capable of higher current and better support, but only after proving the rest of the package.

I'll be using a CA v3 with external shunt for a Dashboard.

Battery

To make the most of the volt up, gear down train of thought while using the full capability of the Sabvoton controllers (without pushing them too hard) I decided on 28s or ~102v nominal, 117v HOC.

To get my range target I require about 3.5kwh of energy. That's applying a 40% modifier to my long term around town average on my other bike of 25wh/km. Depending on the situation, the new bike may actually be MORE efficient rather than less, but it will certainly weigh more, has higher rolling resistance tires and will be putting out a lot more power which I will definitely be using, so I think 40% more juice by distance is appropriate for estimation.

To get the peak power I need without excessive sag I need a pretty low ir pack. Based on my experiences with other bikes I don't like the reality of living with a large lipo pack of unknown quality/longevity. I have had very good experiences with 18650's and have built the tools I need to assemble reliable packs. Unfortunately I can't get enough power out of an entirely 18650 pack without ending up with weight and capacity well above the demands of my range requirements. This has flow on effects for power to weight and desired performance, requiring more power and in turn an even larger pack to supply it.

One potential solution is to build a hybrid pack, assembled from 28s12p of Samsung 30q 18650 cells in parallel with a single string of high power lipo cells. Based on recent product releases and testing it seems that the Turnigy Graphene 65c cells are the go to for consistent high C performance with surprisingly long cycle life. I have done some small scale testing with cells of varying levels of power density and the behavior of the current draw follows a proportional split according to pack IR.

So tentative pack specifications are
28s12p Samsung 30q cells - 15.5kg - 65mOhm - 3.6kwh
28s1p 6ah Turnigy Graphene 65c - 6.5kg - 35mOhm - 0.6kwh

All up 22kg, 22mOhm and 4.2kwh. Enough for my range requirement + 20% and enough punch to deliver 30kw efficiently.

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Re: Mid-mount Hubmonster Madass

Post by SlowCo » Feb 14, 2016 4:47 am

I'm subscribing as I think this will be a very cool build. Keep us posted on your progress. Good luck and enjoy building!

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Re: Mid-mount Hubmonster Madass

Post by jansevr » Feb 14, 2016 2:44 pm

Awesome build. I've got one of johns hubmonster as well. Was thinking of doing a mid drive scooter build so I'm sure I could learn a few things from seeing how your project goes.

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Re: Mid-mount Hubmonster Madass

Post by shadow » Feb 16, 2016 10:38 am

This is an excellent set of goals and great initial analysis of your roadblocks.

I would definitely shy away from using a hybrid mix of batteries, but you were probably aware of that and are asking out of a more scientific curiosity. Unfortunately i don't have any expertise to add on that other than to say that the weakest link in your battery pack will ultimately bring about the demise of the rest of the cells, regardless of individual strengths or temporary benefits.

As far as the packaging, fear of lipos, and current output, the solution is out there! 18650's are great, lipos are great too. Is there fallout with lipo? Yes but it is rather simple to test packs beforehand and assemble only the strongest ones into a large pack. HK will also replace packs with crap cells within 30 days. There's really no reason to throw lifespan into the mix considering the pack size and miles traveled. If you oversize the pack and charge only to 80-90% you will extend significantly beyond 500 cycles.

500 cycles * 100km = 50,000km. At that point you can chuck the pack and buy an even better pack for less money, 3-5 years down the road. Planned obsolescence. Plus, if any packs go bad it's much nicer to be replacing cheaper packs than let's say graphene or high-end 18650's (although i agree they do look awesome). Cost is always a factor at some point, so that's why i bring that up. Some people spend more money on the "brand name" of the battery as some sort of "insurance policy" but there really is no great return on that kind of thinking. Best case scenario you spent extra money and got perfectly equal cells and nothing goes wrong for the entire lifespan (100,000-200,000km), worst case something goes wrong anyway and there's no warranty that applies to this kind of custom build. Personally i like spending the money on extra range, backup packs, good quality electronics, cell monitoring etc.

I follow you 100% on the madass being a good choice for registration purposes and quality components. Sadly, it's a little more difficult to have a large tube running down the middle of the frame, making packaging of square items more difficult (battery pack, large controller). As someone that has had to engineer every single component on my electric motorcycle (i looked at every damn combination of batteries, voltage ranges, controllers etc. out there) the best advice i can give you is that when you run into a contradiction, check your premises, you will always find that one of them is wrong. There are no contradictions, just compromises you have control over. Building the battery compartment will be tough, so focus your energy on that aspect rather than looking for an easier way or a different battery.

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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Feb 17, 2016 3:55 am

shadow wrote:I would definitely shy away from using a hybrid mix of batteries, but you were probably aware of that and are asking out of a more scientific curiosity. Unfortunately i don't have any expertise to add on that other than to say that the weakest link in your battery pack will ultimately bring about the demise of the rest of the cells, regardless of individual strengths or temporary benefits.
At the end of the day what I'm planning on doing is a bit experimental, I'm certainly not aware of anybody else that's built a pack like this - certainly not at this scale. It will be interesting if nothing else to see how it behaves.

The alternative homogeneous pack assembled from lipo becomes significantly more heavy/bulky. Even cells at the energy dense end of the hobby lipo spectrum do not come close to the density of a hybrid 18650/lipo pack. Packaging the 18650's is quite a lot easier. In an ideal world I would use EV quality large format pouch cells with an appropriate chemistry for the compromise of energy and power density that I require, but achieving that in NZ on my budget is not feasible.

I will say I'm not afraid of lipos - I have discounted using them (as the primary pack component) because of reliability, packaging, inadequate energy density and total expense. Shipping HK packs to NZ in the quantities I need becomes quite costly.

Regarding building the battery compartment etc, it may not be as difficult as you suspect. The madass is pretty weird looking already, this thing doesn't need to be all elegant curves and flowing design. Battery box will mount under and follow the main tube. Small mounts will be welded onto the main tube and it will be bolted on. Battery casing at this point I'm thinking a compartmentalized aluminum monocoque structure that has two rows of 18650's running longitudinally with series string of lipo in the middle. Cells will all be tested prior to pack assembly. The Lipo cells will be tied to the 18650's at cell level as well as at main output. Cell level parallel ties I will have running with some sort of fusing for safeties sake. This also allows some room for a big breaker, a DC/DC converter for the lights/horn etc within the one housing.

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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Feb 17, 2016 4:01 am

The teardown

A week or two ago I dropped all the oily bits off the Madass weighing it as I went.

In as new condition with an 80% full gas tank the Madass weighed in at 97kg.

Minus all the bits I didn't plan on keeping it came in well under what I had expected at 59kg
Stripped Madass.jpg

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Re: Mid-mount Hubmonster Madass

Post by SlowCo » Feb 17, 2016 6:31 am

Is there room to mount the hub motor to the swing arm just in front of the rear wheel? That way you'll have a lot of room left for a battery box. Like this:
Stripped Madass.jpg

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Re: Mid-mount Hubmonster Madass

Post by shadow » Feb 17, 2016 1:51 pm

this is fun, here's another option to explore.
Attachments
madass_option.jpg
madass_option2.jpg

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Re: Mid-mount Hubmonster Madass

Post by ohzee » Feb 18, 2016 11:31 am

Nice donor bike. Look forward to this project.

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Re: Mid-mount Hubmonster Madass

Post by wineboyrider » Apr 16, 2016 11:56 am

.
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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Apr 17, 2016 5:08 pm

wineboyrider wrote:.
I assume that's a subtle request for an update? :p

Current status is motor is inbound, hopefully in a crate between here and China. I can't proceed with designing the subframe until I have the motor in hand. Subframe will mount the motor, the rear mount point of the battery and the original kickstand and footpegs will bolt to the bottom. Hope is that I can retain all the original geometry in terms of footpeg position, ground clearance and chain angles - but as this needs to be pretty precise I'm limited in what I can do until the motor arrives.

I have my pair of Sabvoton controllers (120v100a), I have ordered a hydraulic Clutch lever/master cylinder and a pressure transducer to set up a left grip variable regen lever while retaining the hydraulic rear disk brake with the foot control. I have a Domino throttle with a number of buttons to set up variable maps. I still need to order a shunt, a number of connectors for terminating phases and battery connectors, a high current breaker suitable for 250amps

Battery wise I'm still un-decided. I have sized up going all graphene HK packs and accepting a lesser range, but I'm still leaning towards a hybrid 18650/Graphene build using 30q's.

Battery is probably one of the last things I will do as I can get the bike up and running with one of my existing packs.

Simultaneously I'm changing things up on my Giant DH comp to a mid-mounted battery (rather than on the fork), a QS 205v3 in all 17" rolling stock. Like a mini-supermoto with pedals.

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Re: Mid-mount Hubmonster Madass

Post by wineboyrider » Apr 17, 2016 8:48 pm

Just hope to see how this build ends up I love the Madass lineup. :?
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Re: Mid-mount Hubmonster Madass

Post by John in CR » Apr 20, 2016 1:00 am

59kg with only the motor, controllers, and battery to add other than wiring and supports, that's great. Is the down tube (the main tuber and gas tank) steel or aluminum? If it's steel then I gotta find myself a MadAss locally, because I'd definitely cut the bottom 1/2-2/3rd off to make it more squarish and significantly larger to become a battery box that's an integral part of the frame.

If you pull the rear wheel assembly off during the process, please weigh it. I've lost enough weight not that I wouldn't be concerned at all running HubMonster in-wheel at high power with my ventilation strategy. Bluefang noted that his HubMonster ran noticeably cooler with his Sabvotons. You can also talk to him about his mods to increase current limits on Sabvotons if you want to squeeze a bit more out of them, though you'll probably want to do some cooling mods on the motor.

A couple of things to note:
-If you stay with the stock axle flats width, the flats are on different planes (a common practice on high power scooter hubbies), so you have to take that into consideration in your motor mounts. It also prevents normal fixed dropouts, because it makes it difficult to impossible to just slide the axle in and out. I go clamping type dropouts to avoid the issue, and I cut a lot of the unnecessary axle off and cut new flats on the same plane.
-Don't just lop off the 10 pin hall connector before cutting back enough of the shrink to identify the 2 sets of halls in relation to the connector pins. My newest one and Steveos have green shrink on one of the sets of halls, which does correspond with Green/Yellow?Blue set of phases, so hopefully that's the factory's new standard. If not, don't worry, I have the pin-out for their hall connector, which has had the same standard for years.

Ever since I saw a MadAss at the grocery store a few years ago I've wanted to do an E-MadAss, so I can't wait to see how yours turns out.

They told me yours was out the door Friday, so the wait is almost over. Exact timing depends mostly on the ground routing from the factory to their air cargo company in China.

John

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Re: Mid-mount Hubmonster Madass

Post by Scottydog » Apr 21, 2016 7:21 am

Someone beat you to it! Sounds like your's will have more pep!! :D

http://www.technologicvehicles.com/en/g ... xjE8csUW70

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Re: Mid-mount Hubmonster Madass

Post by wineboyrider » Apr 21, 2016 9:04 am

Scottydog that's onl 2300 Euros. Seems pretty reasonably priced.
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Re: Mid-mount Hubmonster Madass

Post by Hillhater » Apr 21, 2016 7:47 pm

It may have a similar name, and even come from the same manufacturer, but its certainly not the same frame or components as the ICE Madass.
And 1.5kW ?
Infact i am pretty sure i have seen similar bikes from China on Alexpress.
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Re: Mid-mount Hubmonster Madass

Post by John in CR » Apr 22, 2016 12:21 am

Yeah, while those have a nice look, they're more of a kids' toy and not remotely comparable to Ohbse's donor bike or build. That black thing above the rear wheel is to little motor.

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Re: Mid-mount Hubmonster Madass

Post by Hillhater » Sep 11, 2016 6:22 pm

Any progress Ohbse ?
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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Sep 17, 2016 4:14 pm

Some, but not nearly as much as I would like! Career had been getting in the way.

I have 1500 Samsung 30Q cells arriving this week, I have pretty much decided on a 28s 15p pack for a total of 4.5kwh. This will easily cover my desired range and provide enough power for my stage 1 performance goals (which I may never progress to stage 2, this will probably be terrifyingly fast as is)

I have got my two custom sprockets made up, one 30 tooth that bolts to the brake flange on the hub monster perfectly and a 49 tooth rear. With a HOC pack voltage of 116v that should put to speed at 140kph or 87mph. That's a full simulation, including aero, pack sag etc. This was optimal for the speed range I anticipate using but also optimal for 1/4 mile use. This is 428 chain, hopefully with two large sprockets and lots of tooth engagement it won't break.

Critical thing that I have changed my mind on is I'm now going to extend the swing arm and mount the motor ahead of the rear tire. This is for two reasons, one is packaging - it simply uses much more of the precious space available. Two is chain tension, especially under regen braking. With motor on the swing this is no longer a challenge. Three is by increasing wheelbase it will be significantly more stable and able to use substantially more wheel torque and accelerate faster.

I have built up a full kinematics model of the bike and its suspension, the extended swing arm does not negatively impact what was a fairly bad design to start with.

I need better controllers. The Sabvoton units I purchased are trashy. Ideally I would like a pair of 24 FET irfp4568 FOC controllers that aren't massive and have firmware/software designed by someone competent. This should mean the battery is the bottleneck in power delivery.

Next tasks are to chop up swing arm, extend, strengthen and build motor mount plates. Machine hub monster shell to remove last traces of the wheel flange and take the brake flange inboard by 5mm. Design battery housing and CNC cut from aluminum, cnc cut cell spacer and weld together the 420 cells (maybe 448, we will see)

I have made progress on lots of other little things such as left grip hydraulic master cylinder with pressure sensor for controlling regen braking

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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Oct 02, 2016 12:09 am

Further update - battery pack is shaping up to be 28s18p of Samsung 30q cells. No hybrid pack.

In practice what I've found is the 30q's are dramatically better under pulse discharge loads than I had expected, I'm seeing ~12mOhm IR on my test cell doing 10, 20 and even 30a discharges. A ~25kg pack with 502 30Q's will deliver >5kwh and deliver >50kw power peaks, far more than my controllers and probably well into saturation on the hubmonster. No need for any additional power density. Added upside is my effective range is now more like 140km of around town use and probably ~75km on the highway. I'll probably only use a fraction of that and still charge daily to a lower voltage.

I've got all the cells, nickel, revised my spot welder and have lots of 6ga silicon cable ready to go. CNC cut battery housings should be done by tuesday.

Also made some progress on the drivetrain, I've located a machinist with the gear to tidy up the motor, extend my swing arm by the required ~90mm and build a solid motor mounts to capture the axle securely. Hopefully see some progress on that front this week too.

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Re: Mid-mount Hubmonster Madass

Post by Ohbse » Jan 06, 2017 4:40 am

Some progress has been made on all fronts, though it's frankly not been at the top of the EV priority list what with building lots of packs for other people and a replacement pack for my daily ridden DH Comp.

The swingarm has been extended 100mm to encompass the Hubmonster (though now no longer capable of being a hub)
Swingarm extended2.jpg
Swingarm extended2.jpg (53.34 KiB) Viewed 2790 times
Tig welded seamless tube, full back purge, heavy bevel with a root pass and then a hot top pass which I'm in the process of filing back for paint. Should be more than strong enough for some big wheelies. Still to be sorted out is the axle mounting scheme, but it should be pretty easy. Basically C shaped torque plates will replace the existing passenger peg mounts you can see here, motor should be able to slot in and then will have another full capture plate with set screws clamp onto the axle and bolt to the torque plates. Should be pretty bomb proof with 20mm plus of tight tolerance steel holding the axle.

The hubmonster shell has been machined, removing the flange and associated meat. This removed probably about a kilo of steel! I could probably get much more aggressive with lightening the hub but frankly I can't be bothered for small gains. Still need to strip the rest of the paint off the shell and re-spray. Unfortunately this machining did reveal a couple of casting flaws with voids that I will need to fill. Purely a cosmetic thing.
Hubmonster shell2.jpg
Hubmonster shell2.jpg (44.54 KiB) Viewed 2790 times
If anybody is wondering, this is what the hubmonster stator looks like from the rear. LOTS of copper and very well made, I have tested all the specifications to make sure it matched the figures John had provided and it actually slightly exceeded them with 15.7 mOhm phase to phase resistance and 2.6a no-load at ~90v. While this is apart I'm replacing the thermal cutout switch with a suitable temperature sensor.
Hubmonster stator2.jpg
Hubmonster stator2.jpg (65.22 KiB) Viewed 2790 times
Gearing has been finalised with a 30 tooth front sprocket and a 49 tooth rear. These are 428 chain which is a small upgrade in width from the 420 that came on the bike originally. What I'm hoping is the large front sprocket and low motion (due to having the motor in the swing arm) means that this will live. If I smash it then I will have to go to bigger brother. This gearing ratio means that with a 72v nominal pack HOC with the standard rear tire size with NO field weakening the bike will top out at 102 km/h or 63mph. Utilising the over-speed function on the controllers should mean I can push this beyond 150km/h, possibly as much as 170 km/h before effective thrust tapers to zero in a full tuck.
Sprockets2.jpg
Sprockets2.jpg (57.63 KiB) Viewed 2790 times
On the topic of battery, I have decided to change direction slightly and stick to 20s voltage. This is for many reasons, but mostly because I don't have to go to higher voltage to get the performance I want with the controllers now available. Lower volts means less danger, less complexity, easier charging, monitoring etc. The pack configuration is looking increasingly like 420 Samsung 30Q cells configured as 20s21p so a theoretical 4.5kwh. This will easily cover my range requirements laid out in the first post and will deliver 30kw power peaks when required.

Here's a sample I cut today of the battery mounting scheme in miniature.
Battery housing sample2.jpg
Battery housing sample2.jpg (53.26 KiB) Viewed 2790 times
All of the battery termination will be CNC cut 0.2mm sheet pure nickel, probably two layers.

Housing material is 8mm Acetal. The plan is to have two sheets of this with the honeycomb pattern machined out, additional acetal will provide the lateral support and then a steel structure will wrap around the pack and tie it back to the frame. Effectively it will be two packs like this side by side with the controllers mounted immediately behind. This should result in the battery leads from positive and negative only needing to be about 100mm long. Phase leads will also be very short at ~200mm.
Battery cut1.jpg
Battery cut1.jpg (60.17 KiB) Viewed 2793 times
I have finished kinematic modelling of the bike, simulating all of the suspension geometry, sprocket locations, centre of gravity (educated guess there until it's assembled with battery etc) and worked out maximum accelerations possible. In theory the bike with the extended swing arm should be capable of 1.2g peak with zero weight on the front tire. In practice that might be a tall order, not least of which is I don't really want this thing to wheelie if I hit the throttle with less that perfect weight distribution, also because with normal-ish street tires it's difficult to reliably do more than 1g of longitudinal acceleration.

With the given gearing, the torque constant of the hubmonster and the specs of the bike (185kg total weight) I need precisely 645 phase amps to deliver 1g of acceleration. I can maintain that 1g until about 50km/h before I hit the battery current limit at 400amps and wheel torque starts to taper off. Dialing in a small amount of field weakening to extend top end I should be able to hit 100km/h in about 3.65 seconds. Pushing the speed as high as it will theoretically go (aero limited) this thing should run something like a 13.0 in the 1/4 mile but will be hitting 90% of top speed by half track.

I'm going to limit the use of this 'turbo' mode to the track and very, very occasional street use as the suspension components nor geometry are really suitable for this kind of ball tearing performance! 30kw on a bike that originally had perhaps 3kw on a good day is definitely a good kind of overkill.

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Re: Mid-mount Hubmonster Madass

Post by kdog » Jan 10, 2017 5:47 am

Damn ohbse- that's awesome. Keep us updated.

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Re: Mid-mount Hubmonster Madass

Post by John in CR » Feb 14, 2017 12:50 am

Awesome work so far Ohbse. One thing though 100mph on 20s = no way without heat stress IMHO. That said, mine did 67mph on 20s running in-wheel, so if you've got a lighter load, better aero, and/or flatter terrain then maybe I'm being overly cautious as usual. BTW, my 67mph number wasn't my max possible, since it wasn't a fully charged pack.

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Location: Auckland, New Zealand

Re: Mid-mount Hubmonster Madass

Post by Ohbse » Feb 14, 2017 8:25 pm

Thanks John. As per usual everything takes longer than anticipated, not so much because it's hard or more involved than I expected, just that I have much less time to work on it than I thought.

Regarding 100mph - you're absolutely correct, this will be an unsustainable speed, however based on the numbers it should be possible as a burst. That's all I'm interested in obviously, as it's hard enough to maintain 60mph around Auckland motorway network (due to traffic), let alone 100! It will absolutely cruise at 100kmh/60mph without any heat issues. I have modified the stator with temperature sensor near the windings and will have thermal rollback configured in the controllers to dynamically reduce current based on temperature. I also have some additional ferrofluid which should dramatically improve the continuous rating.

I will be happy if I can crack 140kph and a 13.XX quarter mile, anything further is icing on top. Reality is this will be ridden primarily in traffic on 50kph roads the vast majority of the time.

I have made a little more progress with CAD work on the pack design, this will be CNC milled from multiple layers of HDPE, the outline looks like this:
pack outline.gif
pack outline.gif (45.97 KiB) Viewed 2320 times
This is 220 cells, there's two layers for a total of 440 Samsung 30Q cells or ~4.7kwh. This is dramatically more than my original desired specs requires, but is necessary to get to the peak performance potential of the motor and controllers I've ended up choosing (~30kw power). Plus having an enormous but dense and unstressed pack is very appealing.

There's two layers of HDPE supporting each layer of cells like in my previous example, all of which is encapsulated in additional HDPE to form a complete large, stiff, sealed battery block with exceptional energy density that should be very safe. This will have a yet to be designed steel frame which will bolt to mounts welded to the chassis. This steel subframe will also support the foot pegs and kickstand.

Cell termination is all done with CNC cut 0.2mm Nickel sheet, probably two layers. The final termination running to the controllers will be reinforced with soldered copper to an externally accessible bus bar machined from either brass or copper. All wiring to controllers and motor is crimped 6ga Silicone and as short as possible, likely only about 110mm long, with phase leads of about 220mm.

I have stripped and re-finished the modified hubmonster as well as replacing the thermal sensor, so that's ready to go. I have continued chopping up the swingarm and have worked out how to complete the motor mounting plates. I will remove the bent smaller diameter lower tube that forms part of the triangle, replacing this with a larger diameter tube that's straight and filling the void between both with 10mm steel, similar to the footpeg mounts in the previous photo, but larger. Additional 10mm thick torque plates with set screws (to lock any axle rotation) then completely encircle the axle flats and bolt to the swingarm gussets with 6 bolts. Should be dramatically stronger than the original piece and be able to easily deal with the torque output.

Unfortunately when removing the original sprocket one of the bolts sheared below the surface of the hub. Despite using penetrating fluid and a torch to pre-heat, it was seized in there really well. Fortunately a work colleague is a machining boss and has experience with using his mill to remove stuck bolts, so I just need to get him to spend some quality time and get it extracted.

So I'm getting there.

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