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Battery Question - How do you decide what battery you need?

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    Battery Question - How do you decide what battery you need?

    After a lot of research, I am a little confused about batteries.

    The Bafang is designed to run off a 36 volt battery, does the 48v or 52v battery cause problems?

    What is the advantage of 52v over 48v and how do you monitor battery usage?

    Is there a performance difference between the 48v and 52v batteries?

    Is there a formula that can be used to convert voltage and or Ah into some kind of operating range?

    Is there any truth to the assertions that the higher the Ah, the longer you can ride ( if all other factors are equal)?

    Info on this would help me greatly.
    Thanks

    #2
    Um, designed with 48V. Don't think anyone has a 36v except me.
    Battery usage can be managed by odometer. Or adding a wattmeter. I KISS and run until the battery sputters and never do it again based on mileage.
    Small differences. My 48v 20Ah does 30, 52v 20Ah 31.2mph.
    Heavy throttle users an old time Endless Sphere guys use 0.75Ah/mile
    Yup more Ah more miles. My 20Ah gets me nearly double the mileage of my 11.5Ah
    As always, YMMV

    Comment


      #3
      yeah if anything the new bafang drives are designed for 48v.....to be safe i would recommend you stay away from both 36v and 52v and go right in the middle :)

      Comment


        #4
        Cyber,

        To compare the different batteries, you have to know how much energy each can hold. The unit for energy is Watt Hours (Wh).

        Wh=Ah*V (Multiply the packs Ah rating by it's voltage).

        A 20Ah 24V pack has the same energy as a 10Ah 48V battery. Each has 480 Wh of energy. Range is proportional to energy. A 960 Wh battery would take you twice as far.

        So, that lets you choose a battery, based on how much work it can do for you.

        To figure out how many Watt Hours of energy you need to achieve your range target, it's a lot harder. You must estimate the Wh/ mile consumption of your bike. That can vary significantly. With mild pedaling I use about 18 wh/mile on my fatbike, at mostly around 15-20 mph. That's just one example. You can find various posts with range and pack specs stated, and figure out other people's Wh/mi usage to get more data. That's how I did it. I settled on an estimate of about 25 Wh/mi for a fatbike before choosing my pack, and have fortunately found that to be conservative, in my case.

        How and what you ride will make a huge difference in how much battery you need for each mile traveled.


        Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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          #5
          So many different factors, I recently built BBSHD 1000w for a fatbike using mainly for off-road trails. I have 11ah 48v battery, and use pedal assist mostly (levels 0 -9). Most of the time I was in PA level 4.

          It also depends on your chain ring also- I have the lekkie bling ring 42T and the Shimano HG300 12/36 9spd.
          So in the hardest gear 12T with 42T chainring its showing 35-40km/hr on the display while peddling (not too hard)
          I used "Karls Secret Sauce" BBSHD programming https://electricbike-blog.com/2015/0...ing-the-bbs02/

          TLDR;
          I got 67km (mostly off road with some on road), using mostly PA lvl 4 hardly any throttle with 11ah 48v battery, 42T chainring, 4" fatbike tires
          Last edited by jakethe5nake; 04-20-2016, 08:17 AM. Reason: EDIT: Really sorry my bad, I misread my "TRIP" on the c965 thinking it was current trip. But I think it is lifetime distance, I got another rough number from google maps timeline 31.9 km

          Comment


            #6
            So I used the info above and went back to my touring bike notebook and this is what I discovered.

            The Shimano 105 cassette on the Felt V85 is an 11-32. Looking at the options if 42t vs 33t on the crank, I get 36.1 gear inches vs 28.4 gear inches. So the climbing will be much better with the 33t...going to buy that. Top end will go from 105Gi to 82.5Gi but I am building a climber, not a road bike. Using the notes from the above, I used the very conservative figure of 20Wh per mile, so am going to buy the 48V 20Ah battery, which should give me a range of about 50 miles in pedal assist mode...which is probably longer than my butt can hold out😁.

            Thanks for all your help!!!!!

            Comment


              #7
              Originally posted by Cyber.snow View Post
              So I used the info above and went back to my touring bike notebook and this is what I discovered.

              The Shimano 105 cassette on the Felt V85 is an 11-32. Looking at the options if 42t vs 33t on the crank, I get 36.1 gear inches vs 28.4 gear inches. So the climbing will be much better with the 33t...going to buy that. Top end will go from 105Gi to 82.5Gi but I am building a climber, not a road bike. Using the notes from the above, I used the very conservative figure of 20Wh per mile, so am going to buy the 48V 20Ah battery, which should give me a range of about 50 miles in pedal assist mode...which is probably longer than my butt can hold out😁.

              Thanks for all your help!!!!!
              Sounds good. One thing - if you mean the Might Mini, it is 30T, not 33T.
              Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

              Comment


                #8
                nice one, now just need to figure out that chain line
                I was a little disappointed when i installed the mighty mini to my full suspension Giant Trance because the chain line was worse than using the raceface with the


                Apart from removing gears from the cassette and adding spacers other option I guess is some kind of custom made chain tensioner-franken-pulley

                Comment


                  #9
                  Thanks for the correction on the smaller crank tooth count. It improves the lower end even more. I think I am convinced to buy both the 42t and the 30t since the closest good LBS is about 2 hour drive.

                  I think removing just a couple of the cassette gears and sliding spacers in behind should solve the problem with a good 80% solution which ain't perfect but will get the job done. Thanks for the link, learned a lot there.

                  Comment


                    #10
                    Originally posted by Cyber.snow View Post
                    Thanks for the correction on the smaller crank tooth count. It improves the lower end even more. I think I am convinced to buy both the 42t and the 30t since the closest good LBS is about 2 hour drive.

                    I think removing just a couple of the cassette gears and sliding spacers in behind should solve the problem with a good 80% solution which ain't perfect but will get the job done. Thanks for the link, learned a lot there.

                    I knew it was a good idea to get both chainrings. Luna was out of stock for the mighty mini for a while. I'm glad I have the 42T bling ring and the 30T mighty mini now. I'm thinking the 30T more for winter and snowy climbs

                    Comment


                      #11
                      Originally posted by Eric Luna View Post
                      yeah if anything the new bafang drives are designed for 48v.....to be safe i would recommend you stay away from both 36v and 52v and go right in the middle :)

                      Really?? Then why does it say elsewhere on this site that 52V is the best thing since sliced bread??

                      For years, the electric bicycle market used legacy designations for power system voltages, like 24V, 36V and 48V. This was because the earliest systems used the common 12V Sealed Lead Acid (SLA) ba…


                      "There is nothing wrong with a 48V system, or even a 60V, or 72V system. We’ve seen them all. However, if you plan to buy an ebike kit over the next year, we recommend that you consider the benefits of a 52V battery."

                      I needed to get a Slimline battery - that one isn't even available from Luna in 48V so I had no choice but go to 52V. It certainly seems like the Luna shop is leaning well toward 52V as the BSSHD standard - so you're saying that you wouldn't recommend using that voltage? I'm confused.

                      Comment


                        #12
                        I think he means that 48V is a safe bet for most bafang systems & doesnt require much messing around. The main differences/drawbacks are some displays wont measure battery properly at 52v (which means you'll have to get something like "batman" to measure battery level) and the voltage when it goes under half.

                        Karl has a good article about it. The good part is as your battery gets goes under half the voltage doesn't drop to the "ho-hum" zone (loss of power & throttle lag) like the 48v might do
                        One of the more common questions I get asked is whether people should buy a 48v or 52v battery to drive their ebike mid drive kit. How much power you use on your builds is a choice everyone has to …


                        I'm still learning all this, hope it helps

                        Comment


                          #13
                          Different voltages will be preferred for different circumstances. 48V and 52V both have pros and cons, depending upon your priorities.

                          48V is going to be more reliable. 52V is faster but of course more power is harder on things, and higher voltage causes electronics to fail a bit more easily. If you aren't after that extra performance, or if you value reliability over speed, 48V is a good recommendation.
                          Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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                            #14
                            Originally posted by JPLabs View Post
                            Different voltages will be preferred for different circumstances. 48V and 52V both have pros and cons, depending upon your priorities.

                            48V is going to be more reliable. 52V is faster but of course more power is harder on things, and higher voltage causes electronics to fail a bit more easily. If you aren't after that extra performance, or if you value reliability over speed, 48V is a good recommendation.

                            and I've heard the BBSHD is super "under-rated" (says Karl) and pretty much takes anything you throw at it

                            Comment


                              #15
                              Originally posted by jakethe5nake View Post


                              and I've heard the BBSHD is super "under-rated" (says Karl) and pretty much takes anything you throw at it
                              Correct. But I've had a 3 accessories which failed at the higher voltage.
                              Fabrication is fun! Build something today. Show someone. Let them help. Inspire and share. Spread the desire.

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