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Thread: Complete newbie wants to go EV racing. Am I just dreaming...?

              
   
   
  1. #1
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    Complete newbie wants to go EV racing. Am I just dreaming...?

    Hi Everybody.

    Iím here because Iím seriously looking into the feasibility of building my first EV. Iím a competent mechanical engineer, Iíve built my own bikes from scratch, and I know enough to build a 12v wiring system, but I know absolutely zilch about electronics, and the last time I had anything electric powered was when I was building slot cars as a child. So Iíve spent the last few days going through as many relevant build threads as I can find, and trying to make sense of it all. Iíve sussed a few things out, but thereís loads of terminology I canít even begin to understand Ė you guys are all pretty darn smart eh?

    So hereís my thinking so far. I race flat track in the UK on ICE, but Iím massively inspired by the Alta Red Shift in flat track trim, and also what Preston Petty is doing with the Zero as a base. Both those bikes are way beyond my budget, plus at heart Iím a builder anyway, like I have been for my whole life. So Iím investigating whether I can build it myself rather than ride a bought one.

    I can put a rolling chassis together no problem, and I can fabricate and mount, but at the moment Iíve no idea what I should be mounting. I need a set-up that will see me through a fairly precise fixed routine - six two-minute races in a dayís racing, plus a bit left over for restarts etc. I need around 30-35kw of power, and Iíll be running at around 40-45mph, and Iíd like the overall weight to be the right side of 250lbs, ideally around 220-230lbs. A good controller (with Ďfeelí...?) is essential in terms of sensitivity to throttle response Ė Iíll be racing on loose dirt after all.

    The first question is, does that sound realistic or even feasible? I want to keep everything as simple as I can, so no on-board charger, no DC-DC converter, and no BMS if at all possible Ė can I just go with battery pack, controller, throttle and motor, or is that hopelessly naive? Will I be able to go go air cooled with everything, as it will be an intense two minutes but with five to ten minutes static cool down time inbetween. The tracks do get very dusty though, so possibly that will cause an issue with an air-cooled motor?

    I know Iím very much lacking in knowledge, and at 63 years old Iím not desperately keen to understand every little nitty gritty or flux reducers or 2P or all the other things Iíve no idea what they are. But you guys are ploughing forward into the future, and I figure just as Iím happy to pass on 50 years of ICE bike building knowledge to those coming up behind me, you may be of the same mind. Iíve no idea what amps or voltage might be suitable, or what type of battery I might need, but if thereís a tried and trusted combination of parts that work well together, and can be assembled and wired by someone who has a desire to make it work and isnít afraid to ask about what he doesnít know, Iíd appreciate any help or advice please. Thanks in advance.


    PS: Oh, and to make matters worse, Iím in the UK as well.....

    PPS: Just for general interest, here's one of my builds. On the one hand, it's as far removed from hi-tech electric as possible - ancient side-valve ICE with magneto ignition - but on the other it's remarkably similar - direct drive, no clutch, no gears.... ;-)

    PICT0021.jpg

    PICT0048.jpg

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  3. #2
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    Hi
    while i am no expert by any means i would call your taks quite managable.
    To find what you need, i would look at the conversions of either dirt bikes or the smaller (like ex 250, 125 ccc) conversions.
    compare that with the engines you have atm. to find your desired power.

    racing 6 say 7 heats of 2min within a day at aprox 45mph would mean a total distance of just say 12..15 miles which is quite doable with a smallish pack.
    48 volts nominal motor and say 12 to 16 pices 40ah cells should be roughly 30-35kg
    for a starter:
    https://www.youtube.com/watch?v=Wj_OjgApCEo
    maybe read his build description on the mentioned webforum..
    for racing i would consider a bigger motor but it gives you an impression what a 5 cont 17Kw peak motor is capable of.
    Remember:with electrics you need less rated power compared to ice - cause you have much more torque at any rpm...

    on endlessphere there are multible smallish and/or off road conversions for getting a feel what is doable.

    You could even consider using high power rc lipo batteries and build say 2 packs and recharge between races. even lighter cause you will be able to push more current through these without massive voltage sag.
    so 2 or 3 packs of say 12-14s 12000mah weight should be around just 4-5kg each racing pack..
    at 30C (2min) these could deliver 300amps cont. (rated for up to 50C which is like 70 sec discharge)

    Hope that helps you a little to get started.

    Keep us updated

    greets

    flo
    Last edited by flo; 4 Weeks Ago at 0059.

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    Again,
    not what you really want appart from two facts:
    run-time more than 10 min, weight stated less than 60 kg... but with shocks,+++
    so a bigger motor and a bit more batteries
    https://endless-sphere.com/forums/vi...p?f=12&t=82158

    just food for thought

    flo

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    Hi Flo, many thanks for the information. I see your point about lipo, but from what I gather they seem a little dangerous for a beginner - my good lady already thinks I'm going to end up blowing myself up or setting myself on fire - or both... But it seems a good 48v set-up would give me enough power and keep me within my weight limit fairly easily. I'll do some more research on that endless-sphere forum, I hadn't looked at that one, so that will help my understanding. I suppose in my simplistic way I thought you might be able to buy ready-made battery packs, but everyone so far seems to make their own - presumably bought ones would be too expensive? Looking at the various air-cooled motors, with windings exposed through the slotted cases, it doesn't seem sensible to be blowing gritty air through them, so I suspect I would need to go liquid cooled. I'll be honest, I am intrigued by the whole electric racing thing, but the more I find out, the more I wonder if it would take me too far out of my depth. I can raise a reasonable budget for this, but I don't want to spend a lot of money to make something that ends up not doing what I want because I don't have enough knowledge (or indeed just turns to smoking ruins, the photos of controllers in just such a state I've seen on here fill me with trepidation). That's certainly not to say I'm giving up on the idea by any means, but obviously I need to learn a lot more about it all yet - I have no idea what "12-14s 12000mah... at 30C (2min)" means at all for example..... But at least I know what I'm hoping for is doable, so that's a great plus to start with, thank you for that.

  6. #5
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    Hi
    edit__for sounding to lax about savety ---
    edit
    I would not rule out lipos right away. These need to be treated just right with little to no room for error. Thankfully todays tech. makes them usable once you know how to do so. For example cut off voltage, over charge or discharge-
    Using a dedicated lipo eqipment -from a acurate set controller, dedicated lipo-charger (set corectly) and a battery managment system is a must in that case but it will take care of safty.
    All this info, i am sure you will get once you have decidet on a particular power system.

    Ok 12s 12000mah at 30C:
    A single lipo cell should read aprox 3,8V under load or charged to 4,2V without load. so you take 12 of them in series to create a nominal 48V system. Same as with lead, there you would take 4 of 12V each batteries in series..
    The term C describes both, the batteries Capacity and their power rating in relation to their size (amperage). in my example 12000mah or 12 amphours.
    So c being 12 amp hours means you could pull 12 amps for one hour (1C) or 24 amps for 1/2 hour (2C)
    having a potent liopo could nowadays mean to have a c rating of nearly 60c continous means you could drain the bat theoretical in 1/60 of an hour or 1 min. Depending on the batteries capacity this gives you also the maximum amperage
    Example: 60 c on a 3Ah cell means 180 amps while on a 10Ah cell you can pull 600Amps. Of course only if both cells rated for 60 C.

    That is also the reason i mentioned rc lipos.
    First off you do not need a high capacity for each relatively short distance race and secondly most bigger cells tend to be of lesser power-rating. (You do not want to drive your ev for 1 min very powerful but rather drive 2hrs long distance (1/2 C).
    RC car and f3 pilots on the other hand need full power for short times (just like you) and thus there are lots of lipos with high power-density.
    As said a ballacing charger and never to over fill or totally drain your pack (read a little reseve) will see to it that no fire should happen. Btw modern lipos do not burn as easy as in years gone by.

    If all this still feels to dangerous for vou there is another chemistry, while being LIthium based is not possible to burn:
    Have a look for LIFEPO(04) chemistry. Calb is one of the mfg`s for a starter.

    do not despair, it might be confusing in the beginning..

    greets

    flo
    Last edited by flo; 3 Weeks Ago at 2209. Reason: soundet to lax on safety and thus hazardus

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    Thanks again for the help. I think I get it, so if say I had four of these:

    https://www.overlander.co.uk/lipo-ba...ersportxl.html

    (I can't seem to find any 12v ones, but I presume a little extra voltage isn't an issue?)

    ...then that would give me enough for one race? Then I have a second set of four for the next race, and recharge the first pack in the meantime? Assuming I can plug into the track mains supply, which probably wouldn't be a problem. And cell balancing is done off track by having a decent charger rather than anything BMS on board?

    If I was using say an ME1302, would I get enough power at 48 volts? It seems to need 96v to peak? Or should I look for a better motor for what I want? I see some of the water-cooled ones can possibly be used without plumbing/radiators for short duration, I've convinced myself air-cooled isn't feasible with all the gritty dust.

    Sorry to bother you with all these questions, I feel like I did fifty years ago when I took my first ICE to bits and wondered what the hell all the endless little parts were.....

  8. #7
    Junior Member Ted Dillard's Avatar
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    Quote Originally Posted by flo View Post
    Hi
    have no fear of using lipos. using a dedicated lipo charger and a battery managment system will take care of safty. That and a Low Voltage Cut Off set to right value on your controller.
    Seriously? Not much would get me to start posting again, but seriously? That's a downright dangerous thing to advise anyone, much less a confessed "Complete newbie".

    Every SINGLE builder I know personally who built lipo packs, with the exception of one, either burned his bike up, or nearly burned his shop down, and mostly both. Do some research. A LOT of research, and then come back and tell me "have no fear of using lipos", please. There's plenty of information here, but the most is on Endless Sphere, of course.
    Last edited by Ted Dillard; 3 Weeks Ago at 1415.
    Power in Flux: The History of Electric Motorcycles
    www.powerinflux.com

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    Wow Ted! I only read to half way down that link before my brain fried, never mind anything else.....



    Appreciate the warning, thank you....

  10. #9
    Senior Member Stevo's Avatar
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    [QUOTE=

    If I was using say an ME1302, would I get enough power at 48 volts? It seems to need 96v to peak? Or should I look for a better motor for what I want? I see some of the water-cooled ones can possibly be used without plumbing/radiators for short duration, I've convinced myself air-cooled isn't feasible with all the gritty dust.

    Sorry to bother you with all these questions, I feel like I did fifty years ago when I took my first ICE to bits and wondered what the hell all the endless little parts were.....[/QUOTE]

    Voltage controls motor RPM. With that motor you will want 90+ volt to get up to 6000 rpm. You can overvolt a bit, but at your own risk. That motor will be competitive, but you'll need an expensive controller like Sevcon or Kelly and someone to program it for you.
    Original build: http://vorworxemc.wix.com/vorworx
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4

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    Thanks Stevo, at least I sussed one bit out right.... So really I'd need $3k worth of batteries and hardware before I start!

    http://www.electricmotorsport.com/ev...d-charger.html

    I was already thinking of a Sevcon Gen 4 (people seem to have more trouble with Kelly's?) but with the price of that plus a motor plus all the bits and pieces, I'm getting close to the cost of buying a secondhand Zero (or more than a brand new KTM E-Ride, although I don't think they'd have quite enough power).

    Mmmmmm.... I knew it wouldn't be easy....

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