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Thread: Off Road Electric Kick Scooter Build

  1. #21
    Mentally Underclocked mDust's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    Unless the rear axle is somehow a freewheel, I would think trying to spin ~3hp worth of motor would have a pretty large braking effect.

    It's a cool project, especially for the budget. I have a huge backlog of projects that I've yet to have the time (all work and no play makes Jack a dull boy.) to get started, let alone completed. My damn sig is evidence of this... I planned an e-bike a while back and reading this just bumped it up closer to the top of the to-do-list.

    Thanks for the inspiration!
    I'll procrastinate tomorrow.

  2. #22
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    Quote Originally Posted by mDust View Post
    I planned an e-bike a while back and reading this just bumped it up closer to the top of the to-do-list.
    Hit me up if/when you do decide to take the plunge. Whether electric bicycle or motorcycle I have some good links for you.
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  3. #23
    Draco Dormiens Nunquam Titillandus Technochicken's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    The controller arrived, along with a twist grip throttle, a fuse, and a few other small parts.

    Next to a DVD for size reference:



    I replaced the handlebars with the bars and stem from a scrapped mountain bike.





    What I've mainly been working on is building a new platform. At first I thought about just buying a sheet of 1/8" aluminum, but I decided to see what I could come up with with materials I had on hand. I realized that I had a large amount of carbon fiber tow left over from the bicycle I built. I built a frame to stretch the tow over, and layer by layer formed it into sheets by soaking it in resin and clamping it between two pieces of plywood. The final sheet has 5 or six layers in each direction. I'm sure the carbon/resin ratio is not the best, but it still is unbelievably strong.

    Here's the sheet:





    Cut to shape:



    Since CF isn't very abrasion resistant, I cut a top layer for the platform out of a scrap sheet of polycarbonate I had lying around, to stop the CF from wearing down. I cut the polycarbonate platform a little bit wider than the carbon layer, so that the polycarbonate will take any impacts, rather than the carbon. Right now, I'm working in bonding the two layers together. The resin I used on the carbon does not bond well to the polycarbonate. I've found that CA glue bonds the two very well, but I haven't thought of a good way of applying CA over such a large surface area.

    Polycarbonate:



    That's all for now. I've ordered a few more parts, like a battery charger and a master power switch, and I'm waiting for the batteries to come back in stock.

  4. #24
    Mentally Underclocked mDust's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    Nice work. Are you going to put some grip tape or something on the polycarbonate? You could also cut some grooves into it if it's thick enough. I imagine it would be pretty slick with a little sand or water on it. I'd hate to see you break bones on the first ride and not be able to ride it again for a month...
    I'll procrastinate tomorrow.

  5. #25
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    OOC, what charger and cut-off switch?
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  6. #26
    Draco Dormiens Nunquam Titillandus Technochicken's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    @mDust:

    Shoes seem to have pretty good traction on the polycarbonate, but I'm going to experiment a bit to see if I'll need grip tape.

    @x88x:

    I had a 25$ gift card to Amazon, so I got a imax b6, which should tide me over until I can get something more powerful.

    The switch is a Hella master power switch. It's rated for 100 amps continuous, and a lot more than that for short bursts.

    The Turnigy 5S lipos I've been looking at have been out of stock for a while, and I've been thinking about using these 15C Zippy's. A pack made from those would be able to put out 150A continuous, which is more than enough, but in your Honda thread you noted that the Turnigy's seem to be better quality than Zippy's, so I may just wait it out.

  7. #27
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    Quote Originally Posted by Technochicken View Post
    The Turnigy 5S lipos I've been looking at have been out of stock for a while
    Gee, I don't know why that would have happened..
    [EDIT]
    Fair warning, assuming my finances are in order when they get re-stocked, they will be out of stock again quite shortly thereafter...
    ...need another 100 to finish off the pack...
    [/EDIT]


    Something you want to consider with hobbyking lipo is that it is much happier (and safer) if you don't try to push it to it's spec. Particularly with the lower-spec stuff. About half the rated C-rate is the general rule of thumb for max recommended output. So if you're wanting 150A out of the pack, and you build it with 15C cells, I wouldn't go any smaller than a 20Ah pack. If you're only building a small capacity pack, it's definitely worth it to splurge on the nice cells. Any idea what sort of range/runtime you want on this thing?

    For the switch, do you know if that 100A is the carry current or the break current?

    The imax b6 is a decent entry level charger. It should do what you need. Once you decide on a pack size, if you are expecting to use this regularly at all, you may want to look into a charger that can handle the whole pack at once.
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  8. #28
    Draco Dormiens Nunquam Titillandus Technochicken's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    The motors I'm using should pull just under 200A when stalled at full power - which should never happen during use. It should draw well under 50A during typical use, and I'm estimating 20-25A at full speed on flat ground. I'm planning on a 10Ah pack to start out, but I have space under the deck to upgrade it to 15 or maybe even 20 later. The purpose of this vehicle is for tooling around, not actually getting me a long distance, so any battery life above 30 minutes is fine.

    I'm not sure about the switch. Here are the specs:

    - Continuous rating: 100 amps
    - Surge current: up to 1000 amps
    - 3/8" copper terminals, silver-plated

    http://www.robotmarketplace.com/prod...-SWHELLA1.html

    I've seen it used in a number of similarly sized EV builds, so I think it should be alright.

  9. #29
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    A few things I would note on the batteries:

    1) With 10Ah you're probably not going to get 30m of runtime. Probably looking at more like 15-20m, depending on ride style.

    2) I would recommend getting some sort of cell monitor. If nothing else, a cell-log or similar to keep an eye on at least one pack. If you keep them in a healthy range, the rest of the cells shouldn't vary much.

    3) Make sure you don't over-discharge the cells. General rule of thumb is to only discharge them to 3.6V and not charge them over ~4.1-4.2V, depending on how careful you want to be. Most lithium chemistries have very distinctive discharge/charge curves, with the majority of the charge lying between two voltage levels, and on either side being what we call the 'cliff'. Basically, above a certain voltage (~4.1V with LiCo), the voltage spikes. And below a certain voltage (~3.6V with LiCo), the voltage drops precipitously. What this means is that if you pass either of those points, it is very easy to over-charge or over-discharge (respectively) the cells. Add in the fact that you get very little benefit from passing either of those points, as those points are at ~90% and ~10% state of charge (SOC), and it's really just not worth the risk. These are great batteries, and can be very safe and dependable (or I wouldn't be using them on my motorcycle), but can also be seriously dangerous if not treated properly.

    For more information on these cells, check out this thread.
    http://www.endless-sphere.com/forums...p?f=14&t=19956
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  10. #30
    Draco Dormiens Nunquam Titillandus Technochicken's Avatar
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    Default Re: Off Road Electric Kick Scooter Build

    Over discharging the packs shoudn't be an issue, assuming they all discharge evenly. The Kelly is programable, so I can set a hard low voltage cutoff, and a soft cutoff where it reduces available current.

    As far as monitoring voltage, I've been looking at something like this, which could give me the entire pack voltage, so I have a rough idea of how much time I'll have left:

    http://www.adafruit.com/products/705

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