Help me understand the basics

Discussion in 'Electric Bicycles' started by s_beaudry, Oct 22, 2008.

  1. s_beaudry

    s_beaudry Member

    I have a very good mechanical background in all things gasoline, but I fall very short when it comes to electrical motors and theories....

    Here I am throwing around ideas for a new push trailer and I am thinking of going electric maybe.... I just need to understand what parts are needed and how batteries get setup and attached to eachother.

    Lets start with this motor...

    If I used this motor, what is the simplest and safest way to set it up to work?

    Do I need a controller, and what is a controller?

    Do I use 2 standard car batteries, how do I connect them?

    How do I regulate my speed, what kind of throttle?

    I appreciate any feedback, the simpler the explanation the better!

  2. ozzyu812

    ozzyu812 Member

    Here's a good place to start your education: Wish I had started there! LOL!

    Poke around for parts here:
    Of course there are many others, but this a good one and just looking at what available is education.

    Car battery trailer has been done. If you have the car batteries already it go with car batteries. If you don't get the scooter batteries. A car battery weighs 50 lbs or more and you get 12v. A scooter battery weighs under 20 lbs for the same 12v. There is no reason I can think of why you can't use car & scooter batteries together.
  3. bluegoatwoods

    bluegoatwoods Well-Known Member

    I read this post this morning, s beaudry. I though about giving as much of an answer as I could (not much).

    But then I thought, "Nah. Someone will have something better."

    And ozzy came through. Good job!

    It's pretty neat how info can get around from those who have it to those who need it so quick and easy, isn't it? And you'll probably get more answers to boot.
  4. ozzyu812

    ozzyu812 Member

    slight correction

    the 12v scooter cells are about 10lbs. i was thinking 20lbs because my packs weight that. 2 cells in each.
    don't even fool with a motor that is less than 1000w. you'll want more power within a month if you get a 600w.
    Here's a good example for $140

    Thanks for the compliment Blue. Most ppl think I'm insane! They're right btw. lol
  5. s_beaudry

    s_beaudry Member

    Ozzy, just so I am sure I understand this....

    Are you saying that a small scooter battery is going to give me the same amount of battery life to drive a motor?

    In my thinking, which may be wrong, I would think that the larger the size 12v battery, the more amps it would hold inside and be able to provide the motor....

    Am I wrong?
  6. duivendyk

    duivendyk Guest

    Battery storage capacity are stated in Ampere hours (Ah), 10Ah means that the battery can deliver 10 Amps for 1hr,or 5Amps for 2 hrs,or 2 Amps for 5 hrs.This does not tell you directly what the stored energy is, which is what you really want to know.Energy storage is in Watt.hrs or KiloWatt.hrs KW.hrs (that's what you pay for at your Elecric Co).
    To get the energy stored in battery you multiply the Ah capacity by the battery voltage, a 24V,10Ah battery stores 240 VA.hrs of energy or 0.24KW.hrs.Let's assume you had a motor that uses 15 Amps at 24V or 15x24 VA or 360 Watts of power (1 VA= 1 Watt).Power use is energy use per unit of time.So how long will it take until our battery is out of juice?,the stored energy 240 Watt.hrs divided by the power used (360Watt) or 240/360 ,or 2/3 hr or 40 minutes.Think this over&you'll get up to speed.
  7. ozzyu812

    ozzyu812 Member

    Don't over think it build it and have fun! :cool:

    I read duivendyk's post 3x's and now I have to take a migraine pill.
  8. s_beaudry

    s_beaudry Member


    Thank you for that formula! I knew there had to be a way to figure this stuff out!

    So, what you are saying is that the best bet for a battery would be one with the highest "AH" as this would last longer with a motor?

    Is it this simple?
  9. duivendyk

    duivendyk Guest

    Yes,but energy storage is also proportional to battery voltage,a 24V 10Ah battery stores twice the energy than a 12V 10Ah one.Basically battery size&weight and Ah capacity go together,however the energy storage/weight ratio also depends a great deal on on the battery type,as does the energy/cost ratio (sorry about that engineer speak Ozzy, take some Tylenol).Lead acids,like what you have in your car are cheap, quite heavy but fairly robust.The smaller ones frequently are the SLA type (sealed lead acid),they have no vents.You need deep discharge type batteries NOT the automotive type,which are the topping-off type
    Next in line, NiCads and NickelMetal hydride,a lot more energy storage for the weight,and higher cost.Nmh are an improvement over Nicads (less toxic) and are becoming more established.That's what you'll find in the Hybrid cars like the Prius.
    Lithium batteries, much more energy storage for the weight but not a lot smaller than NmH (they are quite lightweight),your cell phone is likely to have one.Still some production kinks to be worked out, more temperamental,cannot be completely discharged.But look like the wave of the future.Go to Wikepedia for more info on batteries.
    If you know your operating voltage,say 36V for your motor, you can simply compare batteries by Ah capacity,for instance your motor takes 10A and you have a 15Ah, 36V battery,or three 15 Ah,12V batteries in series,it will last you 1.5 hrs (15/10=1.5)
    Last edited by a moderator: Oct 24, 2008
  10. ozzyu812

    ozzyu812 Member

    Tylenol Migraine

    I took Tylenol Migraine, when I posted #7. Thank you very much.

    I don't think my SLA's last, even when new, as long as your equations suggest. Are they no load run times?
  11. duivendyk

    duivendyk Guest

    That first image is intriguing ozzy, a half track downhill cruiser?,tell me more.What little experience I have had with SLA's was not all that favourable.I look upon them with considerable suspicion.You may need more than Tylenol for your migraine,you could be cognitively challenged by my posts (this is not uncommon),which is obviously a great strain on the old brain.I think you should desist from reading taxing posts and thus spare your prefrontal cortex overstimulation,which frequently is the underlying cause of migraine attacks.
  12. ozzyu812

    ozzyu812 Member

    I'm in the middle of moving. I maybe offline for a week or 2.
    Last edited: Oct 26, 2008
  13. SirJakesus

    SirJakesus Guest

    Duive your posts are great. Don't stop with them.
  14. duivendyk

    duivendyk Guest

    Thank you, Sir Jakesus for your kind comments, it takes my mind of the stock market and gutter politics. Occasionally I get some flak&ridicule from the seat-of-the-pants-try-it-for-size& get-the-wind-in-your-hair but don't bother me with no stinkin math fraternity,Fortunately there are the "more thoughful members" around,to whom I addressed my first post,which I must admit was a trifle on the abstruse side.This caused something of a stir.Such is life,I make no apologies.
    Last edited by a moderator: Oct 26, 2008