1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Water bottle battery

Discussion in 'Electric Bicycles' started by rh1968, Oct 9, 2010.

  1.  
    rh1968

    rh1968 Just Joined

    Joined:
    Oct 9, 2010
    Messages:
    39
    Hi all,

    I'm a newcomer to this electric bike business but due to illness I'm looking to electrify my road bike so that I can carry on using it. I've chosen the motor I want (Bafang 250W, I only want assistance, not full "electric moped" capability) but I'm dithering about the battery choice. For aesthetics and to keep addons to a minimum I'd ideally like to use a water bottle shaped battery like Cytronex use to fit in the bottle cage, but as far as I understand their battery only works with their whole system (I know they've got a retrofit kit coming out soon but I was told it will cost around £1000, which seems excessive). Does anyone know of any other manufacturers that make this shape of battery? I'm hoping to find one that's either Li-ion or LiFePo4, 250W and around 12AH.

    Any tips would be very much appreciated!
  2.  
    flecc

    flecc Member

    Joined:
    Oct 25, 2006
    Messages:
    27,863
    I don't think this is likely. The Cytronex battery is 4.5 Ah, the other bottle battery around is the larger li-ion one on the Powabyke X models, 6.5 Ah, though both are 36 volts.

    A 12 Ah battery would be more like a torpedo than a bottle and be far too bulky and heavy for the bottle mounts.
    .
    Last edited: Oct 9, 2010
  3.  
    Bigbee

    Bigbee Just Joined

    Joined:
    Oct 12, 2008
    Messages:
    445

    Ive seen one ,I'll check on Monday when Im in the office which manufacturer it was.
  4.  
    TheWarden

    TheWarden Just Joined

    Joined:
    Mar 12, 2010
    Messages:
    17
  5.  
    rh1968

    rh1968 Just Joined

    Joined:
    Oct 9, 2010
    Messages:
    39
    Thanks so much TheWarden, that's exactly what I'm looking for! Have emailed to enquire cost of a single unit and shipping, will post here if/when I get a reply.
  6.  
    Jonah

    Jonah Pedelecer

    Joined:
    Aug 23, 2010
    Messages:
    431
    Location:
    EX38
    German water bottle battery

    saw these on a German website mentioned in another thread.

    Google Translate
  7.  
    rh1968

    rh1968 Just Joined

    Joined:
    Oct 9, 2010
    Messages:
    39
    Thank you Jonah as well, those look intersting too. You guys are all stars!
  8.  
    daniel.weck

    daniel.weck Pedelecer

    Joined:
    Aug 8, 2009
    Messages:
    1,205
    This would work nicely for a 2.3Ah A123 pack I think:

    1L/33oz. stainless steel Water Bottle/Wide Mouth/Drink on eBay (end time 05-Nov-10 16:57:31 GMT)

    [​IMG]

    ...assuming 2x 6s1p packs in series, using this stacked layout, one alongside the other (204mm long, 60mm wide on a square section):

    [​IMG]

    Each A123 26650 cell measures 68mm in length (including soldered tabs), and approximately 30mm in diameter including padding.

    My A123 pack (awaiting delivery) will look more like the ones shown here, so it wouldn't fit in any bottle:

    http://www.pedelecs.co.uk/forum/ele...mpanys-replacement-batteries-4.html#post87723



    [​IMG]
    [​IMG]
    Last edited: Oct 11, 2010
  9.  
    daniel.weck

    daniel.weck Pedelecer

    Joined:
    Aug 8, 2009
    Messages:
    1,205
    Yes, they have a good choice of capacities and packaging styles.

    For their 36V packs, they use Lithium Manganese (LiMn2O4) cylindrical cells (18650-VT cell, 3.7V 1.35Ah), which have different characteristics than LiFePO4 (3.2V) or A123 nanophosphate (3.3V) cells. Like A123 cells, these LiMn2O4 cells don't need much balancing (so they are probably sold without a BMS control circuit), but they deliver less performance than the larger A123 26650 cells. Also, like Lithium-Polymers, A123 cells loose their performance abruptly when they get near their full discharge, whereas the manganese cells will gradually let go.

    So, for their 36V 5.6Ah battery they use 40 cells (10s4p). They use 28 cells (14s2p) for the 48V 4.6Ah pack, so each cell in this case has a capacity of 2.3Ah (it's the 26650 cell model).

    The overall shape is 280mm long and 78mm wide, so the stainless steel 1L bottle I showed in my earlier post wouldn't be long enough (thus why they mention 1.5L on their website).

    By the way, the Bosch 36V powertool packs typically contain 20x manganese 18650-VT cells, whereas the DeWalt 36V packs contain 10x A123 26650 cells.

    [​IMG]

    [​IMG]

    [​IMG]
    Last edited: Oct 11, 2010
  10.  
    TheWarden

    TheWarden Just Joined

    Joined:
    Mar 12, 2010
    Messages:
    17
    One other thing you may want to consider is that you will need to put the controller somewhere too (e.g. in a saddle bag). I quite like the concept of the "little frog" saddle post battery containers used by EWC which you can buy from a few places now e.g.

    36V Lithium Ion Little Frog ABS Shell Battery Pack For EBike [Frog36V] - $109.00 : BMSBATTERY!, The Art of Battery

    It isn't as stealthy as a water bottle but you can get a 10Ah version and it holds the controller too. It is also quick and easy to remove when you want to do some proper exercise. Some pics of the innards:

    Endless-sphere.com • View topic - BMSBattery/ECityPower Experience
  11.  
    rh1968

    rh1968 Just Joined

    Joined:
    Oct 9, 2010
    Messages:
    39
    Yes, I like the design of the "Little Frog", unfortuntely I've made enquiries and you need about 5 inches of seatpost showing between the saddle and top tube for it to fit, which I haven't. Considering that coupled to a beam rack though.
  12.  
    daniel.weck

    daniel.weck Pedelecer

    Joined:
    Aug 8, 2009
    Messages:
    1,205
    That's what the Sparticle kit uses:

    Electric Bike Sales - Shop Online for Electric Bikes, Electric Vehicles and Cycle Accessories - Sparticle 250 Watt Conversion Kit V.3.

    Electric Bike Sales - Shop Online for Electric Bikes, Electric Vehicles and Cycle Accessories - Brompton Sparticle

    I'm not a fan of the aesthetics, but it sure does the job.

    For my upcoming small-capacity A123 battery pack, I am planning on using a waterproof Chivalry frame bag, or a Topeak / BBB / Avenir equivalent. Although they are designed as saddle bags, I have a cunning plan to make them fit as front luggage. I am starting to receive the parts for my e-Brompton refactoring (incremental improvement), I am going to cleanup the wiring using different connectors from the ones we've seen so far on this forum. Stay tuned ;)

    http://www.triplebuttedcycling.co.uk/index.php?cPath=55

    [​IMG]

    [​IMG]

    [​IMG]
  13.  
    JohnD

    JohnD Just Joined

    Joined:
    Feb 8, 2010
    Messages:
    46
    The Bafang '250W' with a 36v 9amp pretty much results in an electric moped - but if you do the power calculations you can see why.
    :D
  14.  
    daniel.weck

    daniel.weck Pedelecer

    Joined:
    Aug 8, 2009
    Messages:
    1,205
    I can see what you mean, but for the sake of clarity I'd like to add that your statement holds true when using a throttle, not when using the pedelec/PAS (Pedal Assist Sensor).

    For example, I have never used my 8-Fun bike as an "electric moped". The motor kicks-in when I need it - based on my cadence input - so the assistance effectively switches on when riding uphill / against wind / heavy-loaded. etc.

    But yeah, the little Suzhou Bafang unit packs a punch :D
  15.  
    piotrmacheta

    piotrmacheta Finding my (electric) wheels

    Joined:
    Jun 23, 2009
    Messages:
    312
    The battery in the saddle-bag idea is a good one but the bottle battery is something I would go for as the weight is lower down.
    I'm currently trying to mount an eZee battery under the main tube on my mountain bike - it will just fit and it's as low as it can go.
    I'd love a water bottle battery as well - I was thinking of using the LiPo stick packs from the RC world and linking them together but haven't go round to trying it yet.
  16.  
    daniel.weck

    daniel.weck Pedelecer

    Joined:
    Aug 8, 2009
    Messages:
    1,205
    I agree totally. I mentioned the saddle bags not to use them as such, but to mount them somewhere else on my Brompton bike :)

    My "Chivalry" frame bag was used under torrential rain and heavy snow last winter, but the controller inside stayed perfectly dry. The key is to buy a decent product with proper waterproof/splashproof zip lines.

    Cheers, Dan
  17.  
    TheWarden

    TheWarden Just Joined

    Joined:
    Mar 12, 2010
    Messages:
    17
    If only you could get the controller circuit size down - it'd be cool to be able to fit the controller and battery in a single water bottle with an all in one connector. I can dream....
  18.  
    fbm

    fbm Just Joined

    Joined:
    Nov 29, 2006
    Messages:
    9
  19.  
    morphix

    morphix Pedelecer

    Joined:
    Oct 24, 2010
    Messages:
    1,964
    Location:
    Worcestershire
    The Powabyke X6 comes well within your budget but as someone else pointed out it's only 6A due to the very small and lightweight batteries. I believe those batteries are much cheaper than larger ones (around £200) so you could probably get a spare battery and still come close to your budget? That would give you twice the distance. Not sure about the motor and power output, I imagine being a smaller battery this bike would have a smaller motor and not be so powerful as the motor you wanted.However since you only want pedal assist this could be ideal..maybe you should put this on your list and try one out.. I have heard from Powabyke that 8A batteries are due out for the X-6 in the next 2-3 months.
    Last edited: Nov 11, 2010
  20.  
    TheWarden

    TheWarden Just Joined

    Joined:
    Mar 12, 2010
    Messages:
    17

Share This Page