Given the same battery....

Discussion in 'DIY Electric Bicycle Hub Motors and Kits' started by Nashville Kat, May 19, 2017.

  1. Nashville Kat

    Nashville Kat Active Member

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    Does a lower wattage hub draw less of the charge to make it last longer?
    (also given the same terrain, say FLAT with no wind, the same bike and rider))

    In other words would a charge in the same battery go further with 250 than 500 watts? I'm sure it would not be double, but I'm guessing that it would go farther but not as fast.

    Thoughts, opinions, controlled studies ???

    post-script- wouldn't it be great if we could swap out a spent bottle battery at a bike shop or a convenience store like a propane cylinder, and just keepin movin on down the road? I think they may do that with electric car cells eventually....

    and I hope the price of batteries comes down!
     
    #1 Nashville Kat, May 19, 2017
    Last edited: May 20, 2017
  2. Dan

    Dan Staff
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    Kat, it really is exciting with the advances in the e-bike tech and battery world. Cool idea about the swop stations. can see that being in the future like propane bottles at convenience stores.

    I receive 5 or 6 google news alerts for a "Motorized Bicycle" search. Ya can set it so any news article with those parameters, is emailed to you. Up until a couple yrs ago, it was always some tragic "the rider was not wearing a helmet" story.
    But last couple of yrs, it has been 4 out of 5 stories about e-bikes. Lots of money going into batteries.

    Like your suggestion for when I bite the bullet and invest in an ebike. Gonna set up a solar panel and have a spare battery always charging. Are the batts some how difficult to swop out? Knowing nothing about em, I had assumed it was just a case of unplugging.

    But, keeping up with tech articles. Battery prices are forecasted to have a looming price drop. Lots of large companies putting large amounts of cash into the technology.

    What I'd really like to do/figure out is a hybrid MB. I have a Prius and it's awesome. The regenerative braking thing is amazing. Most of the time the rear brakes (drums, BTW) don't slow the car with contact and heat generating friction. Rather it turns the wheels into generator, alternators sort of deal. Creating a resistance and slowing the car. Just amazes me. No lost energy. Well, much less.

    For a starter e-bike or hub. What would you suggest? Gotta start learning about em. I personally think they are the future.

    Edit and just to add;

    This is the panel I have set aside for this project. It's pretty cool and works well.

    https://www.harborfreight.com/45-watt-solar-panel-kit-10-pc-kit-68751.html
     
    #2 Dan, May 20, 2017
    Last edited: May 20, 2017
  3. Nashville Kat

    Nashville Kat Active Member

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    I don't know much other than whats here- I wrote an extensive post about my personal situation and asking the questions I've put up here, and when I clicked the final post button- I was suddenly not signed in and the whole thing disappeared so it was very frustrating and I just ended up posting short questions.

    I queried one vendor on ebay and he answered in broken English that the geared hubs rolled better, direct drive gets more torque at higher rolling speeds and so is better for that. I'm 63 and just can't afford to fall off at China Girl speeds anymore- you may have- but probably not- noticed my lamenting that there's no 33cc China girl for the likes of my rebuilt vintage Schwinn road bikes with 700C light wheels.

    I also then viewed a couple of good videos on the subject on youtube- I wish I had posted here but it was late and night and I wasn't thinking- I'll try to relieve those, because they were very informative.

    I'm leaning to a 36 volt 500 watt 700C wheel right now- or possibly even 26 just to get lower to the ground again- but I'd have to buy more and I've overspent again this spring and finding my hyper tension is severely limiting my normal riding after having raced USCF for 14 years long ago. So hoping I may still roll around a bit for a few more years- I feel a little stupid these days- a 63 year old trans woman roaring around on my China Girl builds, but they were handy a few years back and I use them occasionally still with full baskets. Trying to keep older jalopies on the road is getting difficult on a limited income.

    I've seen that Harbor Freight solar panel for several years and wish I had one on my water heater, which I switch on and off at the circuit breaker- it would probably raise the mean temp up some and then use less power for the rest then. Florida is a pretty good place for solar.

    I may get a wheel now- and not be in a big hurry to install it and get a battery later to defray costs and I have a lot of things that need attention car wise and around the house. I like the bottle batteries because they fit within the frame and look not terribly heavy- and that location doesn't get in the way of baskets. And I recently got an older Schwinn Traveler frame that has braze on bottle fittings that might make a great electric build

    anyway- I'm a little bit excited to finally go electric- slow it down a notch and go QUIET, but it will be mostly for emergency transportation needs or convenience, and some just to roll around and not pedal so much because at the moment that's not going too good, although some of my condition may be improving slightly otherwise- I keep peddling up into a physical wall of tension after a few weeks of short intermittent rides- which is a shame because I'm not in bad shape otherwise and want the exercise.

    Thanks, and save your work before posting!
     
    #3 Nashville Kat, May 21, 2017
    Last edited: May 21, 2017
  4. Nashville Kat

    Nashville Kat Active Member

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    #4 Nashville Kat, May 21, 2017
    Last edited: May 21, 2017
  5. Dan

    Dan Staff
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    I hate that, Dear Kat. The type for 11 minutes and it disappears. It's infurating, fer sure!
    Our new host is fixing it for us. The first time Eric and I were in contact, he and I had that happen. But will be fixed this week if all goes well. (Really good guy and is doing all sorts of good for us!)
     
  6. Dan

    Dan Staff
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    Very cool. Thanks for posting Kat!

    After watching that vid. Wondering why CVTs like a scooter or my Prius isn't used? I'm sure it's been thought of but seems you could get the best of both worlds with the addition. Hmmm
     
    #6 Dan, May 21, 2017
    Last edited: May 21, 2017
  7. cannonball2

    cannonball2 Active Member

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    To answer your original question which goes futher 250w vs 500w my answer is sort of yes and no.

    . The main difference in wattage generally speaking is the controller. Surely the hubs are wound to a certain operational voltage/wattage parameter and are better suited to being used as designed but its the controller that is dishing out the juice. I routinely run a 36v 350w geared hub on a 12s lipo which is 50.4v off the charger. Its run on a common 48v 1000w controller. The controller doesnt care about the extra voltage(up to its caps limit) the only issue is the LVC (low voltage cut) is wrong, that means you just have to monitor the voltage with a volt meter and cease operation before damaging the battery pack. I run one 1000w 48v hub on two 4s lipos in parallel which is 33.6v off charge thru a 24v 250w controller.

    Point is with ebikes using the common kit controllers, wattage is actually a function of the amperage/voltage the controller is capable of. As I remember the 48v controller was rated at around 20amps max thats 960w so now the little 350w hub is being fed 960w(max) Its a lot of fun
    at these values speed wise, a function of the increased V/As. I have to be careful not to destroy its little plastic gears on acceleration! Conversely the 48v hub is fairly leisurely in performance with its set up. As to which one goes further with a given motor/charge/pack. If the wattage is the same the system with the highest voltage as it draws less amps, ie 250w@24v will draw more than 250w@48v. 48v goes farther. Conversely given the same voltage the lower wattage goes further.

    Run the highest voltage you can afford at the least wattage you can stand for distance.
    Run the highest you can afford on both for fun!
     

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