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Thread: eGrom by Eco Mouse

              
   
   
  1. #1
    Junior Member Eco Mouse's Avatar
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    eGrom by Eco Mouse

    e-Grom (Green).jpg
    The eGrom... stock it comes with a 2000w hub motor, 72v. It currently has 20ah SLA batteries. I want to upgrade to LiFePO4 soft pouches, to fit unique shape. I'm really hoping for 100ah. I can get BMS and Controller all from same battery manufacturer made to my specs.

    Anyway, my question pertains to what size motor and voltage should I be shooting for, if I want Maximum Range and efficiency.

    With my current wheel size, my choices are:
    3000w and 4000w (I'd be willing to go larger 14" wheel if you guys feel 6000w or 8000w hub motor is something I'd need)

    Also, I have a choice of voltages. Currently a 72v system. But I see options for 84v and 96v in these wheel sizes.

    Oh, and bike currently weighs in around 450 lbs with me on it at the scales. This is with the lead batteries currently in it. I've got a preliminary weight of 39lbs (17.7k) with the new battery cells, so I'd imagine the bike with me on it will come in well under 400lbs. (I have a full fab shop, so I can cut, grind, weld and composite any part for my bike)

    But I still need to understand the different motor wattage and what they will give me.

    If I went with an 8kw motor, that could theoretically give me a higher top speed? But will it still drain my battery packs faster if was running within 50% of the motors peak capacity? Let's say that it was capable of 100mph, but I run typically 50 and under. It's that only drawing half of what is asking for and therefore more efficient to over build? I don't need to be going 100mph on 12 or 14 inch wheels. But my thought is, that if I run at half of what's available, I'll use less and it keeps the heat down.

    And what's the deal with 72v, 84v, and 96v options?

    So, I really don't know what I'm doing here... so I took the liberty to draw up the battery pouches just to get a rough idea how much volume they are going to take up. So far it's looking pretty good size wise. Maybe I could add even more pouches depending on my size constraints.

    I'm guessing that in order to get to a 96v pack, I'd need 30 cells @ 3.2v each, right?

    Each pouch cell consists of 23500mAh (and takes up roughly 9 inches x 5-3/8 inches, and not even 1/2 inch thick)

    So this when all connected however they are supposed to be connected, it should be 705 amps, right? According to some online calculator I should be at 67.68kW

    How far can I go on all that juice? Ideally, I'd like to get 300 miles per charge.

    eGrom Battery Layout.jpg
    Battery Pouches.jpg

    Go gentle on me... I don't do electronics, and I'm trying to learn. I prefer concepts to math and formulas.

  2. #2
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    hmmm.... where to start...

    oh - hello, and welcome. Great to have you aboard, and love the enthusiasm (seriously, I do, not kidding).

    Now - as to 300miles range in a motorcycle chassis... that's not gonna happen just yet.
    ...well, maybe if you were happy to ride at a walking pace it might, but otherwise, no - not achievable right now.

    As to 100MPH in a 300miles range bike - well, look, if the guys at Pikes peak and the IoMTTX can't get that sort of performance, that really ought to be telling you something.

    Even at 50MPH you'll be using somewhere in the region of 100W/Mile +/-40% depending on weather, terrain, and the ergonomics of your chassis.

    I'm also not aware of a hub motor which will give you 100MPH, and even if you were to show me one, there's no way in hell you'd get me to ride it - that much unsprung mass at that speed (and you want long travel suspension to boot!!) is a suicide mission - nothing less.

    With regard to the voltage questions - voltage has to do with motor RPM. The higher the voltage of your pack, the faster the motor can spin (within its own mechanical limits of course) and given we're looking at hub motors here, that means the faster you can go.

    Your preliminary weight figures are a little confusing - Li-chem is lighter than Pb but not *that* much lighter. 30 cells at 3.2V and 23.5Ah would give you a nominal pack voltage of 96V, and a capacity of 2.2kWh if you use 100% of that available energy (which you wont). That's enough juice to carry you about 30miles on a good day. That arrangement will also give you a peak current of about 120A, which, at that voltage level, is enough for moderate acceleration but isn't going to get you past about 50MPH once you account for wind resistance - and you'll be running you cells ragged if you try and hold that speed for any length of time.

    All told, this quote "So, I really don't know what I'm doing here..." really sums it all up.

    If this is a process you want to proceed with (and I strongly recommend that you do), then you've got a hell of a lot of reading to do. You're going to have to get acquainted with the sorts of systems other people have used, the various types of motors, their respective pro's and con's, the various types of batteries, their respective pro's and con's, motor controllers, battery chargers, battery management systems; and then once you've gotten acquainted with that lot you need to brush up on chassis design and fabrication because if you're going to try and build something that's 100MPH capable, then that's going to have to have good brakes, good suspension, and a center of mass that doesn't destroy the handling.

    The above sounds like a lot of information - that's because it *is* a lot of information - but thankfully it's not what I'd call a chore to get through it. There are some crackin' projects on here and some excellent build diaries that bring you right through from the stripping of the donor chassis all the way through to first rides.

    Were I to give you a starting point for where I think you're going to have to go to get 100mph performance *and* 300mile range in a chassis you'll actually want to ride, then I'd offer the following:
    - First and foremost, your budget will need to be in the $15-20k ballpark, this ain't gonna be cheap.
    - Forget about dual sport, that ain't gonna happen; Donor chassis will need to be a hypersports tourer, something big but streamlined, you're going to need the aerodynamics to have any hope of getting that range (Hyabusa, Blackbird, ZZR1100, etc..)
    - Forget about hub motors, they're a disaster for handling at higher speeds, and don't have the power for the performance you want. Inboard PMAC or Induction motor is the way to go, and most likely PMAC given the amount of battery space you're going to need, 30kW minimum with a paired controller (Electric motorsports have a kit or two worth looking at)
    - Forget about LiFe, it's too bulky/not nearly energy dense enough; Li-NMC(Nissan Leaf etc..) or Li-NCA(Tesla) in either pouch cells, modules, or 18650 (or 22650 which is the way I believe things are shifting), and I strongly expect that only the latter will actually get you the packing density that you'll need.
    - Charger with a CANBUS integrated Battery Management System, you're going to need to be able to squeeze every available drop from the modules so this will be a must.

    That setup will get you 100mph performance, and a 0-60 time of <6s - to get the 300miles though, you'd need to have a minimum of 30kWh on board and the best I've seen packed into a bike to date is only about 2/3rds of that, and that's the 20kWh option for the Lightning LS218, which is a $40k bike with the basic 12kWh pack.

    So - as mentioned earlier - welcome aboard and enjoy the ride.

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    Senior Member Spaceweasel's Avatar
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    As far as the touring side of things, the bike featured on Richard230's thread on aero is close to what Spoonman is describing - https://www.storm-eindhoven.com/STORM_Pulse.

    That being said, I don't see why a large ADV bike wouldn't work either. You might give up some streamlining, but the basic idea is the same.

  5. #4
    Junior Member Eco Mouse's Avatar
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    Quote Originally Posted by Spoonman View Post
    As to 100MPH in a 300miles range bike
    Thanks for all the info... it gives me a place to start. I believe I might have been a bit confusing talking about two different bike projects. I'm not a 100mph rider, never have been, not gonna start. I was using that as an analogy to try and gain an understanding of how to piece together the right motor/battery combo. I'm really only looking to go 60mph max... as the first bike is just basically a commuter scooter, hence the hub wheel. The Grom is larger than a pit bike, and smaller than a Ninja 250. Right now, the sales literature says it will go 55mph with it's current set-up, but that sounds like with a tail-wind, down hill, crouched down behind the handlebars.

    What I was getting at, was that if I bought a motor set-up that stated that it could go 100mph, and I only ride at max, 60% of that and less, could that theoretically mean that I'd not be taxing that motor as much? I'm really only concerned with being the first bike that can go 300 miles in a real world commuting setting. even if that means that I've got to pack panniers with batteries as well.

    I've spoken with the guy trying to bring graphene super capacitors to the market, as they seem like they could supplement a battery pack, or replace them all together. Loads of energy density, and slow discharge capabilities, like a battery.

    I only picked LiFePO4, because of their inherent safety, and won't terminate into thermal run away if they should get punctured in a wreck. Even Tesla's batteries have caught on fire before. Thankfully, they were isolated enough that it caused no harm to the occupants. But on a motorcycle, you are literally straddling pent-up mayhem with your balls. I'd love to have battery lab capabilities... because I truly believe that a Lithium Fluoride formulation might be the answer we've been looking for this whole time. Plus, it makes industrial waste by-product Fluoride a valued commodity, instead of a nuisance that gets dumped into our municipal water supply.

    I don't really care about costs... I truly believe in this as our future, and being involved at the ground level is just R&D for generations to come. I've built my business around finding ecological solutions, and pairing up with like minded individuals who wish to push beyond the status quo.

  6. #5
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    Quote Originally Posted by Eco Mouse View Post
    What I was getting at, was that if I bought a motor set-up that stated that it could go 100mph, and I only ride at max, 60% of that and less, could that theoretically mean that I'd not be taxing that motor as much?
    It'll mean you'll be using less power - rpm doesn't tax a motor, torque does, so constant speeds aren't really a problem, it's getting to them and pushing through the wind at them that stresses things.

    Quote Originally Posted by Eco Mouse View Post
    I'm really only concerned with being the first bike that can go 300 miles in a real world commuting setting. even if that means that I've got to pack panniers with batteries as well.
    You see, you say that, but in the real world batteries are heavy, and heavy things high up means high center of gravity, and that means tippy handling - so you wind up with a very heavy bike that you can't hold from tipping over, with a center of gravity that makes it want to tip over, and you want to use that in the most tip-over happy environment known to motorcycling??...

    That's not a very good 'real world' situation to be in.

    Quote Originally Posted by Eco Mouse View Post
    I've spoken with the guy trying to bring graphene super capacitors to the market, as they seem like they could supplement a battery pack, or replace them all together. Loads of energy density, and slow discharge capabilities, like a battery.
    NOOOOOOPE - never gonna happen. The power delivery of capacitors is through the roof, but the energy density relative to batteries is nowhere (and I do mean absolutely nowhere) at all. Supercaps have FAR higher energy density than any other type of cap, but that's still not much.

    As to supplimenting a battery pack - yes, they can do this and this sort of strategy is very useful where you're using saggy chemistries, or if you're on very variable terrain where the current load to the motor is fluctuating heavily, OR if you need insane amounts of power on demand like say for climbing pikes peak - in these scenario's they're useful. For 50mph pootling about an urban environment all they do is cost you money and take up space.

    Quote Originally Posted by Eco Mouse View Post
    I only picked LiFePO4, because of their inherent safety...
    NMC are safer and have more consistent cycle to cycle terminal performance, as has been demonstrated by a few members on here, and is something that I'm still marvelling at in my own build.


    Quote Originally Posted by Eco Mouse View Post
    I don't really care about costs...
    lol - excellent.

    Quote Originally Posted by Eco Mouse View Post
    I truly believe in this as our future, and being involved at the ground level is just R&D for generations to come. I've built my business around finding ecological solutions, and pairing up with like minded individuals who wish to push beyond the status quo.
    you should fit right in.

  7. #6
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    My group tried supercaps in various configurations more than 10 years ago. It does prevent battery-sag on takeoffs, and stores energy during regen-braking. However, charging became unwiedly and too fussy.

    With lithium (when new), there is almost no voltage sag, unless the pack is undersized, which will be obvious when the Low Voltage Cutoff gets triggered on a steep hill.

    SLA batteries come in many discharge-ratings and 'internal-resistance'. The Very High Discharge SLA's are costly and the Hawker-Genesis **require** minimum 1C charge rate, which is a large battery charger.

    The Hawkers do not require a supercap because they are very low resistance already, practically a supercap.

    The SLA's do not require a BMS!

    All of this is from actual experience.

  8. #7
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    Your Flouride comment is very interesting.

    Have you read Jim Marrs' books, which cover flouride, too?

  9. #8
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    Once had a 90kph electric 'cycle running off Hawkers. The battery size was only 16AH at 48V nominal, so range was under 10 miles, practical. But charging took only 15 minutes, so it was a great grocery-getter.

  10. #9
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    BTW, imo, the "anwers" to your electric 'cycles are already answered -- in China, where they are building millions a year.

    E-motorcycle journey Sichuan-Tibet(15 days, 2140km)
    https://endless-sphere.com/forums/vi...tibet#p1162852

  11. #10
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    Re: Battery-inventing, contact a once-famous American battery-inventor, handle: "DeafScooter" or something, who got swarmed by dis-info agents, and retired in Asia. He is a real-deal.

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