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where energy is going?

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    where energy is going?

    According to practical data from strava average energy consumption on moderately hilly routes (6-7%) is 7-8 wh/km, on those with light hills 3% - 4-5 wh/km; this means that in the 1st case 470 Wh battery shoild last 67 km, in the 2nd - 106 km! On practice however this battery is hardly enough on road of 1st kind for 25-30 km. Also on 7% uphill energy consumption is 18 wh/km and if all journey is such uphill such battery should last 26 km.

    As to the power needed to go uphill. Again according to data from strava on 6% uphill for 12 km/h it takes 240 w; this means that even 250 w motor for any uphills is quite enough. On practice one person told me that with his 350w geared motor wheel working at full power (which could be much more than that) he has to turn pedals; other users said that going uphill took 500-700-1000 w!
    Last edited by miken; 6 days ago.

    #2
    I recently changed (lowered) the gearing on my bike to help with a short, but brutal hill, that using just the throttle and not peddling requires approx 1200 watts to crest.

    BBSHD, 28 gear-inches, pulling 400 pounds (bike, rider, groceries) ... groan!
    Last edited by ncrkd; 5 days ago.
    Intro: http://electricbike.com/forum/forum/...ntro#post17033
    First build: http://electricbike.com/forum/forum/...0293#post20293

    Comment


      #3
      Remember that some of the energy is going to heat and sound.

      Also, I have a 19.8Ah battery, but after 12Ah it cannot supply enough current to ride the bike quickly, so I stop riding at that point. Who wants to amble along at 10mph?

      Comment


        #4
        So it is either e bikes are absolutely useless and will remain so for good because battery capacity cannot be increased significantly or they can work according to these calculations but people just dont know how to use them. Why to be so concerned with motor power when battery doesn't exist for that?

        Comment


          #5
          Originally posted by miken View Post
          So it is either e bikes are absolutely useless and will remain so for good because battery capacity cannot be increased significantly or they can work according to these calculations but people just dont know how to use them. Why to be so concerned with motor power when battery doesn't exist for that?
          I think ebikes have plenty of range. Most people wouldn't want to ride a bike further than 30 miles.

          I use my ebike for commuting to work every day which is a 12 mile round trip. My ebike is a complete Amp Hog, so the 19.8Ah battery is just large enough to do the job. My round trip commute consumes 11Ah, but after that I can't draw a continuous 30A which is what I need because like need speed. If I were willing to slow down, I could go much further even on my inefficient bike.

          I am going on a 24 mile ride this weekend, and I will carry an extra battery. It is no problem to throw in an extra battery. I have done bike tours which were 20-45 miles per day. The saddle sore really comes in to play after about 35 miles/day. This is when you really grasp what a coccyx (tailbone) is.

          Reducing weight (bike, rider and/or cargo, but in particular rims, tires, tubes/tire slime/tire liners, spokes and nipples) pays amazing benefits.

          Also, lithium ion technology is rapidly advancing, so these cells are simultaneously getting lighter, higher capacity and more economical. Fast forward five years and you will be able to double your range drawing plenty of current at half the price without increasing the weight of a the battery you are using today.
          Last edited by commuter ebikes; 5 days ago.

          Comment


            #6
            Originally posted by miken View Post
            According to practical data from strava average energy consumption on moderately hilly routes (6-7%) is 7-8 wh/km, on those with light hills 3% - 4-5 wh/km; this means that in the 1st case 470 Wh battery shoild last 67 km, in the 2nd - 106 km! On practice however this battery is hardly enough on road of 1st kind for 25-30 km. Also on 7% uphill energy consumption is 18 wh/km and if all journey is such uphill such battery should last 26 km.

            As to the power needed to go uphill. Again according to data from strava on 6% uphill for 12 km/h it takes 240 w; this means that even 250 w motor for any uphills is quite enough. On practice one person told me that with his 350w geared motor wheel working at full power (which could be much more than that) he has to turn pedals; other users said that going uphill took 500-700-1000 w!
            What battery are you using? I have a 750 watt geared hub motor paired with a 52 volt 13.5 ah Luna Dolphin battery. I can get 50 miles (80 km) without totally draining the battery on rolling hills.

            Comment


            • commuter ebikes
              commuter ebikes commented
              Editing a comment
              Wow, that is a really efficient ebike!

            #7
            Originally posted by BK Xray View Post

            What battery are you using? I have a 750 watt geared hub motor paired with a 52 volt 13.5 ah Luna Dolphin battery. I can get 50 miles (80 km) without totally draining the battery on rolling hills.
            So in your case it's 9 wh/km; do you have it about the same on your other rides? According to data from other person who has also geared hub motor it is around 19 on a ride with moderate hill (6%), if he goes slow and smooth 16.

            Comment


            • commuter ebikes
              commuter ebikes commented
              Editing a comment
              I consume 60-65 Wh/mile (37-40 Wh/km) on level ground (average speed 28-29 mph).

            • miken
              miken commented
              Editing a comment
              But you just wrote that you can go 80 km on 700 wh; or is it because part of the ride you were going by inertia and motor was not working? If you go on level ground at slow speeds, like 15-20-25 km/h what the consumption would be?

            • commuter ebikes
              commuter ebikes commented
              Editing a comment
              Just for clarification,forum user BK Xray can go 80km using 700Wh.

            #8
            I have to say I have been pretty impressed with the range I have been getting. I typically ride 17-19 mph (27-30 kph) and I pedal most of the time. However, I don't put a lot effort into the pedaling because I have knee problems that don't let me contribute all that much. I try to do things that improve range just like I would in a car. I anticipate stops and coast down hills. I have the hub in a 20" wheel so it is pretty low geared and doesn't struggle to climb, even on steep hills. This is on a compact long wheelbase recumbent bike that weighed about 32 pounds before being electrified. It is comfortable enough that 30+ mile rides are fun, not painful. Here's a stock photo of the bike that I started with:

            Comment


              #9
              Originally posted by commuter ebikes View Post

              The saddle sore really comes in to play after about 35 miles/day.
              The hurt comes from time in the saddle, 35 miles is about two hours. Get a Brooks saddle.

              Comment


              • commuter ebikes
                commuter ebikes commented
                Editing a comment
                Went on a longer ride today. Saddle sore set in at the 25 mile mark on my Bontrager MTB seat. I will check out Brooks.
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