wanted Mobility Scooter - not working

Discussion in 'Hobby Engineering' started by Sploody, Nov 7, 2018.

  1. Sploody

    Sploody New Member

    Joined:
    Sep 11, 2018
    Messages:
    20
    Location:
    Brisbane
    Hey all,

    I realise this could be a breach of rules since you need to be a member for 90 days before you can post in the classifieds - but i have been given a month off from work due to a massive injury last year (more recent surgery to recover from), so i am going to want something to do during that time which is at least productive.

    Enter my grand idea:
    Always wanted to take an older, broken down mobility scooter, strap as many batteries as I can to it, along with a kickass huge motor.

    I'm already halfway there with a speed controller, 48v LiPo 20Ah battery and a 1.5kW motor but I feel for what I am wanting (skids) is that i may need to double the motor and batteries, OR resolder my current pack into a couple 36v packs for a 72v but lower Ah.

    It just so happens that the injury was to my knee so its totally justified that I get a mobility scooter right?? *nods at everyone, waiting for nods back*


    TL;DR - Cant post on classifieds - does anyone have a broken mobility scooter (broken battery/motor/controller etc) that they want to get rid of? I need a project and to do skids.

    If the wrong area, please move this post or delete

    Thanks all
     
  2. OP
    OP
    Sploody

    Sploody New Member

    Joined:
    Sep 11, 2018
    Messages:
    20
    Location:
    Brisbane
    side thought - if I made x2 36V LiPOs with balancing BMS on each, and an extra set of cables so they can be run in parallel or series, would that interfere with a BMS at all?
    Because on my 48v pack - I believe my BMS is limited to 60A peak 40A cont. with balancing, overcharge/discharge protection etc etc.
    Im asking, as wouldn't the BMS freak out and basically 'turn off' in order to protect the second cell in series which in theory is now receiving double the voltage?
    Or should I simply jerry-rig the thing so it can run in all setups?

    ie all fast connectors for the individual 36v BMS's, as well as connectors ready for a 72v BMS.

    Because if it could be as easy as rejigging my shitty soldering on my current big battery pack to make these two 36v packs, then that would be sweet for getting either some chill range out of it (36v2P), getting some speed (72V1P) and charging will be easy as - plenty of cheaper 36v chargers out there.

    If im making no sense, its because its fkn late and im stuck thinking about all this shit and as mentioned before, havent played with this battery stuff for 5yrs. will happily offer to provide MSPaint images of my thoughts in the morning if people want though :p
     
  3. rainwulf

    rainwulf Member

    Joined:
    Jan 20, 2002
    Messages:
    4,195
    Location:
    bris.qld.aus
    BMS, if it supports the voltage, wont care, as to it, its just a battery of half the voltage, but greater AH.
     
  4. Hater

    Hater Member

    Joined:
    Nov 19, 2012
    Messages:
    2,716
    Location:
    Canberra
    I have a big ass electrical motor that's like 2400W from a multcher if that helps? Runs on 240V though.... although teathered 2400W skids might be a thing?

    You can have it for nothing but postage might be a killer
     
  5. bYrd

    bYrd Member

    Joined:
    Sep 14, 2001
    Messages:
    1,876
    Location:
    NE Melbourne
    Got any elderly friends? Ask around and they should have/know someone who has one lying around. They're more common than you think, and if not maintained often non functional gathering dust in someone's backyard.

    Keep in mind a lot of deaths occur by misuse of mobility scooters (in older people who haven't been properly trained in their use), so don't let anyone else near the thing, especially kids or frail aged. Be a dick with it on footpath/roads and police will also book you rather promptly. Decommission it as soon as you've had your fun.
     
    sammy_b0i likes this.
  6. ninthcircle

    ninthcircle New Member

    Joined:
    Nov 7, 2018
    Messages:
    1
    What a coincidence! I also have a project that needs exactly this (broken/cheap motor scooter for disassembly). I'm super interested in whether OP finds a good source of them.
     
  7. ShadowBurger

    ShadowBurger Member

    Joined:
    Feb 19, 2008
    Messages:
    1,498
    Location:
    Melbourne
    I don't see how a 1.5kW motor and a 48V 20ah LiPo couldn't deliver some nice skids. Assuming a conservative rating of 15C, about standard for a big LiPo, you should have 300 amps @ 48V to play with (BMS / wiring limits notwithstanding), but your motor will max out at ~30amp, so the focus will be around how you set up the drivetrain. The questions you need to ask are:
    • what is the motor's kv rating, or rpm-per-volt?
    • what gearing options and final drive ratio do you have to play with?
    • is the motor engineered for that kind of abuse?
    • can the electronics (ESC) handle the current?
    • what is your target nominal speed at max throttle or is this strictly for stationary burnouts? (low speed requirement = low gearing = more torque for easier skids)
    • is this a brushed or brushless motor? there is a <50% vs >80% efficiency difference respectively
    Motors of that size become expensive, especially when dealing with brushless. A 450W/24V brushed motor runs $130 (used in my motorised toolbox project, can carry a person, has the torque to spin wheels), while going upwards from 1.5kW/48V will be bigger $$$ especially for brushless. Here is a 6kW brushless for example, running up ~$1000, but going with DC you can get a 48V/6-12kW motor for around the $500 mark so it will depend on your budget.

    It's also probably worth me pointing out from experience that mobility scooters have mass produced components that don't lend well to modification - for example the drive motors are often integrated to the wheel hub and use worm gears and plastic housings, greatly limiting them to low-speed, light-duty applications. The wheels tend to have plastic hubs and soft rubbers that will disintegrate if you put enough torque to lose traction through them. The frame is designed to sit the batteries at a low CoG and have bugger all clearance off the ground and no room for a proper axle and a motor. So I wouldn't start with a mobility scooter as your base platform (although a seat from one would be comfy af)

    Not trying to plug my own thread but possibly take a look and see how I built the frame. The design was simple and definitely scalable to your application. https://forums.overclockers.com.au/threads/heavy-duty-r-c-tool-box.1213711/
     
    Last edited: Nov 12, 2018 at 8:54 AM

Share This Page