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48 volt battery selection for etrike

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    With a trike you have a lot more mounting options than typical bicycles. I would be looking at used 'scooter packs'. There always seems to be tons of those available on the used market really cheap from failed rental scooter companies. They are often cheap enough its work the risk that you could end up with a dud but if you do you can still usually harvest the still good cells for a future project or repair of the working packs. Main reason I have not done it is they tend to be long and narrow packs that just don't fit anywhere on a standard bicycle.


      Any experience with Lithium Iron Phosphate Deep Cycle Batteries like used in Golf Carts? They can be wired in series to produce 48 volts!
      Click image for larger version

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      Three times lighter than lead acid and up to 2000 cycles before failure! Click image for larger version

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      Here is a great video on how to keep them charged and maintained over long periods of time/nonuse!


      • 73Eldo
        Giga Member
        73Eldo commented
        Editing a comment
        I like their comparison chart. Looks like that marketing department didn't even run it past an engineer, even the one that drove the train they rode to work on. If they would have said 'other' batteries they would look a little better but picking AGM was an odd choice and not the best contrast for some of their points.

        Just to pick on one of their points lead acid batteries are very easy to recycle because they are very simple so its easy to separate out the parts. I don't think there has been any new lead mined for years now, its all recycled.

      Lithium iron phosphate (LiFePO4) sort of split the difference between lead-acid and the Li-ion more typically used in electric bikes - they are considerably heavier and larger than the typical bike Li-ion

      They are "safer" than the bike Li-ion since they don't experience thermal runaway and the electrolyte isn't flammable

      But to get the full capacity they need chargers specific to that chemistry (they have considerably lower cell voltage than bike Li-ion) and unlike lead-acid they are also fussy about not being stored fully charged so you may lose that ease of maintenance when storing unless the charger will hold them at a storage charge and you put them away like that

      Not many people use them these days in bike applications but that's mostly due to size and weight


      • jbwilli
        jbwilli commented
        Editing a comment
        Thanks ya'll and All points well taken, but I am leaning toward the LiFePo 4x12v16ah in series.
        LiFePo, sealed, thermally protected, charge and discharge internal protection, longer life even if you do not use it @ $240 and under 16 pounds!
        Lead Acid or AGL, half the cost but 3 times heavier @ 48 pounds or higher???
        LiIo 4x12V16h or 20ah, best performance and lightest BUT 3 times the cost $600 and way over my budget to push an adult TRIKE at the beach on level boardwalks and paved bike paths???

        Special charger is not expensive and I am reading way to many good facts about LiFePo batteries vs other choices.
        My main concern was how it would work on a front wheel 48V 1000 watt motor and then I found this answer from a confirmed purchaser and user!

        Q: can I use 4 of the 16ah batteries to power my 1000w motor?
        A: yes in my case i used 4 in series to power a 48 volt 1500 watt ebike, just use heavy gauge wire - #10 or larger
        By doctorpc on September 26, 2020

        I may be next spring before I make a stab at it, and I may change my mind again. I sincerely appreciate all the advice and info!
        Good to meet all of you and......more to come...... I am sure. I now have good sources to run ideas by! THANK YALL!

      • Fred
        Giga Member
        Fred commented
        Editing a comment
        For your trike application where weight and size may be a little less important, IMHO the LiFePO4 option looks like a reasonable one. I used to have a 48V version of these on my small electric Vespa-like scooter and they were fine. As suggested, these days, we mainly see Lithium Ion because of weight, size and in some cases economics due to mass production of those cells.

      • AZguy
        Giga Member
        AZguy commented
        Editing a comment
        Agree, li-iron is a good choice for your application... just don't store fully charged, don't let them run all the way down and you will likely be good..

      If your project is still that far out keep an eye out for used stuff. Pretty good chance you can find a pair of 24v packs in the next year, maybe even a 48v that fits your needs. I checked a few sites I was looking at for used stuff and right now they only have a couple 36v options which won't work for you. With 36v packs you need 36 or 72v system and most 48v's top out at 60 so that would not work. Last summer it seemed like everywhere I looked there were people selling 24v scooter packs for like $30. I think they were around 15ah but were like 18" long and I wasn't sure how I would mount a pair of those on a regular bike.