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  1. #151
    Newbie
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    Jul 2013
    Location
    Southern Illinois
    My Bikes
    two motorized trikes
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    Hi, I know nothing about electric so please be basic in answering my questions. I have a 48v motor that I am trying to get started. I have put 4 lawn and garden 12v batteries to, but when anyone puts a meter on then I get to much voltage. There are no repair shops for electric bikes and have not found anyone to help me here. Can someone help me?? Or at least tell me where to go for help.

  2. #152
    Senior Member DrkAngel's Avatar
    Join Date
    Oct 2012
    Location
    Upstate NY
    My Bikes
    Various "modded" eZips and multiple econversions
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    Lightbulb Care and Feeding of Your Slabatts

    Several years ago, in my "lead sled" youth, I despaired at the lowly SLAs I'd encumbered myself with.
    After rebuilding my oem pack I began researching.

    The care and feeding of the loathsome slabatts.
    1. Never overwork them (never deeply discharge) they become permanently "lazy".
    2. Always feed immediately after working them (recharge immediately) or they digest their own muscle (electrolyte).
    3. They are rated(and designed?) to discharge over 20 hours (1/2 hour discharges do "damage" them more than "rated" use) Don't expect 100's of cycles!
    4. 1/2 hour discharges give less than 50% of "rated capacity" (50% wasted as damaging heat) Especially, excessive heat, during charging or discharging, is damaging.
    5. Don't feed them too fast (manufactures recommend charging at .125C (1.25A charger for 10Ah battery)) a type of permanent "indigestion" can occur (plate corrosion).

    Any wonder that I went Lithium?
    Of course Lithiums are "expensive" so I started recycling used cells .
    See - Homemade Battery Packs

    PS I did purchase and use a BatterMinder Charger-Desulfator.
    I did enjoy a fair degree of success in rejuvenating worn-out batteries!
    A few hours has little affect, weeks of desulfating were required for substantial enhancement.
    Using a desulfating charger constantly has prolonged battery life 200-300%.
    But at $80-$150 for a charger ... is it worth it?
    "Best of all! ... I get to play. ... http://www.bikeforums.net/attachment...&thumb=1&stc=1
    Sorry! ... I'm addicted to improving enhancing.
    With side orders of inspiring enlightening!"

    Acronyms

  3. #153
    Senior Member
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    Aug 2007
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    Huffy Wildwood
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    Price is dropping on these. Panasonic NCR18650PD

    http://www.fasttech.com/product/1233...ah-rechargeabl

    They are popular for the e cigs so there should be a steady supply.
    Last edited by biker; 08-06-13 at 10:58 AM.

  4. #154
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    Recognizing Battery Capacity as the Missing Link

    Interesting article from Battery University about measuring State of Charge (SoC) or remaining capacity for batteries or packs.

    An excerpt:

    Most users see the battery as an energy storage device resembling a fuel tank dispensing liquid fuel. For simplicity reasons, a battery can indeed be compared as such a vessel; however, measuring stored energy in an electrochemical device is far more complex than drawing fluid from a fixed container

    Full article at http://batteryuniversity.com/learn/a...e_missing_link

  5. #155
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    Jul 2014
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    Hey all, new guy from Sydney, Australia.

    Ive been reading a hell of a lot about ebikes/batteries over the last 6-8 months and have begun my first project. A 48v 1500w brushless motor and matching controller, and I'm planning on making a 13S8P li-ion battery with BMS, with the cells coming from some 12 cell laptop batteries. I have already bought 1 battery from the seller and tested the cells, they seem to all be 2400 - 2600mAh and charge/discharge quite well (testing on a balance charger from Jaycar).

    Now i am a bit of a noob when it comes to hands on electronics (this being my first project), but don't get me wrong, I've watched countless videos and read article after article about Li-Ion, LiFePO4, LiCo etc. and understand that Li-ions are the most dangerous when not treated or monitored right (hence the BMS), but I am just after a second opinion.

    Anyway, I am just running this by everyone to get their thoughts and to see if I'm on the right track:
    With the 3.7v 2600mAh cells in 13S8P, that would give me a 48.1v 20.8Ah pack. With the 48v motor drawing MAX 40A, is this a well suited battery idea? As i understand you shouldn't draw more than 2C otherwise you get too high of a voltage sag/heat buildup etc. I will also buy a 40A peak / 20A continuous balancing BMS and wire that into the pack <- my insurance policy
    Now when the batteries are at full charge of 4.1-4.2v, is the total 54.6v too high for the motor? or will it simply 'use what it needs'?
    Secondly, am i right in thinking that if i charge each cell to 4.1v rather than 4.2v, and discharge to say 3.2v rather than 3.0v, will that increase the lifetime of the batteries (number of cycles)?
    Finally, with so many cells coming in a 1S4P configuration, what are people's thoughts on using some coin magnets to temporarily connect these cells in series to balance charge? I have heard people say its a HUGE no no, but then others say its ok. Personally I don't understand how it will affect the charging such that the magnetic field is not changing, and with my understanding, shouldn't cause an issue.

    Thanks all, and I am having such a great time tinkering away on all this stuff. Its nice to finally take my mind off uni studies to find a hobby which is also practical by saving me more money in the long run

  6. #156
    Junior Member 8weight's Avatar
    Join Date
    Mar 2014
    Location
    Sydney Australia
    My Bikes
    old 27 inch roadie, old 26 inch mountain bike, new Repco converted to Electric-26 inch with a 36 volt 800 watt front hub drive 20amp LifPo4 from BMS, 700c Malvern Star with a Magpie3 rear hub motor and a 20 amp 50 to 100 from BMS
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    Wow

    Tell us how you went?

    There's a lot of info at How to Prolong Lithium-based Batteries - Battery University but I doubt there's many here who know details like you have posted well enough to reply.

    Quote Originally Posted by Undertow33 View Post
    Hey all, new guy from Sydney, Australia.

    Ive been reading a hell of a lot about ebikes/batteries over the last 6-8 months and have begun my first project. A 48v 1500w brushless motor and matching controller, and I'm planning on making a 13S8P li-ion battery with BMS, with the cells coming from some 12 cell laptop batteries. I have already bought 1 battery from the seller and tested the cells, they seem to all be 2400 - 2600mAh and charge/discharge quite well (testing on a balance charger from Jaycar).

    Now i am a bit of a noob when it comes to hands on electronics (this being my first project), but don't get me wrong, I've watched countless videos and read article after article about Li-Ion, LiFePO4, LiCo etc. and understand that Li-ions are the most dangerous when not treated or monitored right (hence the BMS), but I am just after a second opinion.

    Anyway, I am just running this by everyone to get their thoughts and to see if I'm on the right track:
    With the 3.7v 2600mAh cells in 13S8P, that would give me a 48.1v 20.8Ah pack. With the 48v motor drawing MAX 40A, is this a well suited battery idea? As i understand you shouldn't draw more than 2C otherwise you get too high of a voltage sag/heat buildup etc. I will also buy a 40A peak / 20A continuous balancing BMS and wire that into the pack <- my insurance policy
    Now when the batteries are at full charge of 4.1-4.2v, is the total 54.6v too high for the motor? or will it simply 'use what it needs'?
    Secondly, am i right in thinking that if i charge each cell to 4.1v rather than 4.2v, and discharge to say 3.2v rather than 3.0v, will that increase the lifetime of the batteries (number of cycles)?
    Finally, with so many cells coming in a 1S4P configuration, what are people's thoughts on using some coin magnets to temporarily connect these cells in series to balance charge? I have heard people say its a HUGE no no, but then others say its ok. Personally I don't understand how it will affect the charging such that the magnetic field is not changing, and with my understanding, shouldn't cause an issue.

    Thanks all, and I am having such a great time tinkering away on all this stuff. Its nice to finally take my mind off uni studies to find a hobby which is also practical by saving me more money in the long run

  7. #157
    Junior Member 8weight's Avatar
    Join Date
    Mar 2014
    Location
    Sydney Australia
    My Bikes
    old 27 inch roadie, old 26 inch mountain bike, new Repco converted to Electric-26 inch with a 36 volt 800 watt front hub drive 20amp LifPo4 from BMS, 700c Malvern Star with a Magpie3 rear hub motor and a 20 amp 50 to 100 from BMS
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    Due to breaking my leg and not being insured when I did so ... as well as at the same time my 3 month old 20a 36v BMA supplied battery developing problems I have been forced to look for options to power my bike, which has been the only way I can get around, the bike has been able to get me around on power only as I cannot peddle until the screws in my ankle are removed, the fact that my battery has been problematic has motivated me to look hard for a solution that I can afford ... I have a trailer which I can attach to one of my my bikes ... so the weighty Led Acid Batteries became an option, new prices of Led Acid batteries make cheap LIFPO4 batteries look like a better option as the prices were comparable amp hour wise, something I was not keen on as they are reported to be short lived ... in the past my experience with Led Acid has been bad, make one mistake and they are stuffed!! and it's time to buy more ... had one set last 2 weeks and all I was asking of them was 11 kilometres (about 7.5 miles) before charging and I peddled all the way as it has been about getting to and from work fast as possible and not so much about making the run easier ... these were six 7amp hour 12 volt golf cart batteries wired to give 36 volts, they were heavy enough to cause the rear wheel to buckle under braking ...

    So here's the thing-

    Found a video on Ebay where this Canadian guy took a sad Old Led Acid battery and converted it to a "Led Alkaline Battery", not only did it go from a very sad state but it started his truck


    https://www.youtube.com/watch?v=Supe1a3LW2U


    Please, anyone doing this, please wear eye protection, cloths that will protect you and have a hose or shower close by in case of accident, as well as please dispose of the acid and anything that may be environmentally damaging, toxic to humans or any life form etc properly.


    Upon further research I found that there is a slowly growing realisation that this not only works, makes led based flooded batteries rejuvenate, but may be technology that may replace Acid based cells.


    Further sites I found.


    Bedini Alkaline Alum Battery


    How to convert a Lead Acid Battery into an Alkaline Battery - Sepp Hasslberger


    Alum-Lead Battery Conversion


    Of course weight is still a problem, in my case I'm going to use my bike trailer to cart 3 batteries to power my 36v 800 watt bike, these batteries I will fix using this method to get me around until I have a decent income again and can replace my LIFPO4, it seems the claims are old batteries not only revive, but have a deeper cycle and faster recharge time.

  8. #158
    Newbie
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    Hah been a while since my question, but I have since finished my battery and took it for a spin on my garbage diy 1500w bike.
    The bike itself was able to reach ~60km/h full curry, and munched quite steep hills without a complaint.

    The BMS from Em3ev.com works great if it weren't for my slightly bad cells. But it manages with balancing and so far, no issues. The battery also lasts a good couple hours on throttle only, but does suffer a little voltage sag.

    If anything I should have stuck to 14s so a BMS and charger is easier to come across(even though em3ev modded mine to take 13S), and I feel that for this motor, that extra voltage would really help.

    I've since disassembled my single speed bike and now converting an old dual sus mountain bike to mid drive. All those gears and possibly 80km/h is too juicy to pass up
    Last edited by Undertow33; 10-03-14 at 12:07 AM. Reason: Mo info

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