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Battery Advances, the Myth and the Reality

Discussion in 'Electric Bicycles' started by flecc, Nov 8, 2006.

  1.  
    flecc

    flecc Member

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    Many of you will have read the 50cycles article on the choice of Phosphate technology for the eZee Li-ion battery on safety grounds, with it's references to the dangers of Cobalt batteries. The fact is that cobalt based batteries have been the mainstay for the last ten years and countless millions are in safe use around the world, and I have one nearing a decade old which is still in service. The subject has arisen because of some much publicised laptop battery fires, almost all due to batteries from one manufacturer, and caused by plain bad manufacturing. The fault was that metal particles were adrift in the electrolyte which pierced separator material, causing ignition.

    Cobalt based batteries are indeed more likely to do this if badly manufactured, but I don't think that should have caused anyone to stop using them, they haven't killed anyone. Some years ago, cans of corned beef were produced with improper sealing, causing bacterial contamination which killed many people, but we didn't stop producing canned food, we just put the problem right. So why am I so concerned about this? It's because we've been cheated, batteries using lithiated metal phosphate cathodes have only 75% of the capacity of cobalt based ones. In other words, my typical 15 mile range on the Torq could have been 20 miles. That's why the eZee 10 A/h Li-ion batteries have so little gain over the 9A/h NiMh ones, they should have been over 13 A/h. That's a lot to lose just because a manufacturer in another industry messed up.

    This is made worse because there's no realistic prospect of more range from current developments. I've seen, as I'm sure you have, excited reports of greatly increased range from Lithium Polymer and the like, but in fact these are rubbish. Lithium Polymer isn't going to bring any appreciable range gain since that's not what it's about. Like all current battery research, it's about faster charging, the search for more capacity through density being all but abandoned. Here's the reason why that is. Nickel Cadmium (NiCad) batteries are low density and low capacity in consequence, but are able to charge and discharge at almost instantaneous rates, subject to being kept cool enough. Nickel Metal Hydride (NiMh) are much higher density and capacity, but lose some of the NiCad ability for fast charge and discharge. Lithium Ion density and capacity is very high but the density impedes the flow of current, so charging is slow and in high drain conditions they're unable to deliver current fast enough, something our Torq batteries suffer from. We call that chemical exhaustion, so manufacturers obviously cannot go any further down the density/capacity street at present, it's a dead end.

    Hence the change in direction, and Lithium Polymer is the first step, having returned to LOWER density to aid fast charging and discharge. So why is fast charging the new pursuit of battery manufacturers? It's that holy grail, the electric car. It's obvious that high capacity batteries and 300 mile ranges for cars aren't anywhere on the most distant horizon, so the answer has to be the ability to recharge at lightning speeds during journeys. Big strides have been made in this, Toshiba having already achieved one minute charging of experimental cells, with others close on their heels, and they've said the main application will be transport. It's all very sad news for electric bike users though, since fast charging isn't our current problem, it's very much range. In the future, many fast charge stations along routes will solve the problem, and in London there's already free battery charging provision in some car parks with facilities intended for all electric vehicles, not just the Riva cars that are in use at present. But it'll be many years before we get a network of roadside stations to go with a new generation of batteries.
  2.  
    rsscott

    rsscott Administrator Staff Member

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    Thanks for that Flecc, a very comprehensive view of the current situation!

    Perhaps one area where Lithium Polymer could be useful is the concept of top-up batteries. If there isn't much on the horizon to give us better range, then maybe the facility of adding extra batteries when you need them is something the manufacturers should be looking into?

    From what i've read, Polymer can be moulded into more shapes more easily which would help as I don't really want to have to lug another Li-Ion battery with me. But if small, neatly designed top-up batteries were available, this could be a good selling point.
  3.  
    flecc

    flecc Member

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    Yes, that flexibility of shape is true Russ, and again a benefit of the reduced density of the Li-p electrolyte aiding better current flow. That said, with our present Li-ions containing 10 compact cells and electronics in 11 separate components, the present batteries could be profiled into a variety of shapes. Even more true with the 30 cell NiMh batteries of course, which also could have been inside the frame tubes with a bit of imagination.

    Probably the best additional battery would be the slim one that slid in just under the carrier so leaving all the bike's functionality unaffected.

    Running batteries in parallel has real dangers though, particularly if the existing battery has already been part discharged, since current can reverse from one to another. The biggest danger would be if a cell shorted in one and the content of the other short circuited through it, potentially causing a fire. To avoid these, any batteries used in parallel should feed through diodes which would have to be high power types on heat sinks, incorporated in the bike's design.
  4.  
    rsscott

    rsscott Administrator Staff Member

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    Yes, I'd quite like to see an additional slimline battery that could fit beneath the rack as per the new Schwinn models.

    However to keep costs and complexity down, i'd be happy with only one battery being connected to the motor/controller at any one time. The main On/Off keyswitch could be upgraded to have a Main / Reserve setting. When you run out of juice in one, you just flick over to reserve a bit like on a motorcycle. The main battery is then cut out of the loop.
  5.  
    flecc

    flecc Member

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    I agree Russ, that's the best of the lot and would add nothing to the bike cost. Also perfect for finding out the range on a route/battery without the risk of being stranded without power.
  6.  
    Jed

    Jed Just Joined

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    Even better if the topside of the battery had a solar panel which could top up the battery when not in use, but i'm probably just dreaming :rolleyes:

    thanks
    Jed
  7.  
    flecc

    flecc Member

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    That'd be nice, but I think it's too small. Twelve volt panels the area of the carrier are on the market to trickle a small but useful amount to keep a car battery OK, but needing 36 volts, I doubt if enough useful current would be produced in our dull cloudy country. A thought. Perhaps we should rename Great Britain to Grey Britain.
  8.  
    David

    David Just Joined

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    "It's because we've been cheated, batteries using lithiated metal phosphate cathodes have only 75% of the capacity of cobalt based ones. In other words, my typical 15 mile range on the Torq could have been 20 miles. That's why the eZee 10 A/h Li-ion batteries have so little gain over the 9A/h NiMh ones, they should have been over 13 A/h. That's a lot to lose just because a manufacturer in another industry messed up."

    Very annoying. We should get the message back to 50 Cycles/the manufacturers that a 1/3rd gain in range is worth a lot more than protection against a virtually non-existent risk.

    David
  9.  
    flecc

    flecc Member

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    It's eZee rather than the importer of course which has control over this decision, but such is the obsession with safety these days and the risks of expensive legal action, I doubt if there's the slightest chance of getting any reversal. In truth, it's the whole western world's culture of risk aversion ín every sphere that has gone too far, the silly attitude that there must never be an accident of any sort, no matter what the cost of achieving that.
  10.  
    rsscott

    rsscott Administrator Staff Member

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    It's a tough one and at the end of the day, eZee are the manufacturer and it is up to them to decide the specifications of their bikes.

    We'd all like more powerful batteries and I suspect whatever is current (no pun intended), it will never be enough! Unfortunately battery technology does not follow Moore's law so the gains each year are small in comparison.

    Perhaps the next step is for lighter motors and higher quality components i.e. lighter frames etc. This would obviously drive the price up though, so maybe we might see two distinct markets start to seperate; the cheaper electric bikes and the high-end machines (perhaps £1,500 or more).
  11.  
    flecc

    flecc Member

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    I think that's already beginning Russ, with expensively engineered alloy bikes like the eZee range, and steel frame lead-acid battery jobs with the cheapest of cycle components like that Currie bike at £395 that I posted about.
  12.  
    rsscott

    rsscott Administrator Staff Member

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    Most definitely. With established companies like 50Cycles and new on the scene PowaCycle starting to offer good value bikes that can compete on price with the 'off a container from the docks at Felixtowe' varieties then that is a good thing, especially when backed up with a decent after-sales service.

  13.  
    Ken

    Ken Just Joined

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    eZee batteries

    50cycles note on eZee batteries are slightly misleading.

    the current Li+ battery available on all production models are not
    Li FeSO4 batteries. i.e. they are not Lithium Iron Phospate batteries.

    The two mainstream technology for mass consumer batteries are
    1. Li Cobalt - used in most consumer electrical applicances. Li cobalt is potentially more unsafe and without proper manufacturing and BMS management can lead to runaway reaction.

    2. Li Manganese Oxide - This is the battery that eZee is currently using. Li MnO is proven to be safer. The reason why this compound is less used is because it has supposedly slower recharge time and lower life capacity, however. eZee has a source for a patented LiMnO technology that has proven to be as effective as the mainstay Licobalt with same performance characteristics.

    In recent light of the burning sony laptop batteries as well as REPORTS of several electric bicycle batteries burning (one German while she didn't lose her life, lost her whole house). eZee has issued a little explaination of the general characteristic of our batteries, although it seems to have come across a bit muddled through 50cycles. There has been fire from some other brands of electric bicycles although these are mainly isolated cases and not a big production error like the laptop batteries.

    Application of Li+ batteries for Multicell packs is invariably much riskier than the single cell applications of cell phones, cameras, computers etc.. because electric bicycles are as of yet, still not a mainstay product and production of multicell packs are very minute in comparison.
    Battery management systems for such packs need to be sophisticated to ensure cell balancing during charging and discharging.

    eZee has also experimented with Li+ Polymer batteries and have found the results to be terribly disappointing for the cost.
    eZee is currently experimenting with Li Iron Phospate technology, this is intrinsically very safe and current technology on this allows it to outperform the mainstream LiCobalt. This is however still in progress and is not sold together with current production models.
  14.  
    flecc

    flecc Member

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    I agree that the 50cycles report has been somewhat misleading, but it's undeniable that the tiny gain in capacity that the eZee Li-ion battery has over the NiMh version is nowhere near what it could have been, and that's my complaint. As unfortunate as it was for someone to lose their house, that's one person out of the countless millions of Li-ion users of batteries produced for over a decade now. Once in a while a car's petrol tank explodes as it's vapour content is triggered by an accidental ignition, and there have been countless thousands of them over the years, often on petrol station forecourts, but we still drive petrol cars. The reaction to that German incident bears out my point about hysteria, for that's exactly what it is. Just because there's an incident or one manufacturer makes a mess of their design and/or manufacturing, doesn't mean others can't get it right.

    As I reported above, and you also say, Li+ Polymer is disappointing from an electric bike manufacturer's point of view, not surprising given the direction of top end research. But for eZee bike users, Li-ion has been every bit as disappointing, if not more, which was what my post was complaining of. Regardless of the eZee patent, their Li-ion capacity does not match what a cobalt based battery could have had.
    Last edited: Nov 10, 2006
  15.  
    flecc

    flecc Member

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    An added comment on this subject.

    The only cobalt problem I know of is the fire risk one resulting from poor manufacturing standards, the problems relating to batteries having multiple cells are common to all lithium designs, with all needing monitoring and control.

    Most of the electric bike production from the Orient has been of bikes made down to a price, quantity taking precedence over quality. There's no doubt that eZee are not this sort of manufacturer, given their design excellence and constant attention to quality control, as Ken knows better than me. It follows that a cobalt based battery specified by eZee would have been a better and much safer battery than many of those produced for bike use so far, and I'd have liked the option of a 13A/h one.

    I hope the current phosphate based research eventually brings us that gain.
    Last edited: Nov 10, 2006
  16.  
    kraeuterbutter

    kraeuterbutter Just Joined

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    is there any bike using light Lithium Polymere cells ?
    i see and read always about Lithium Ion (Mangan) ?!?

    how much capacity are you wanting, and how much weight should such a pack not exceed ? (the costs not considered at this moment, just interest from technical stand-point)

    for example: 37Volt (= 42Volt after charging) with 29,4Ah !! at only 4900g
    that should give some descent range with an e-bike
    (thats the cellweight including soldering the cells together and some shrink-rap also already included)
    --> there would have to be a "box" were this cells than are stored and to mount it on the bike (but that could be very lightweight as well, when done from Kevlar/Carbon in a mould)

    was already possible 2 years ago
    (Thunderpower Prolite Lite cells... iam using this cells now for 2 years myself)
    maxium charge-rate: 2C (so after about 40min full (if you have a charger that can do 60A charge-current *lol* - but i think on a bike with that much range you would be fine with a cheaper, weeker charger and charging over-night)

    downside: like most Litihium Polymere-cells this cells will be only good for 2-3years.. after that (latest 4years said by manufactor) the cells will be dead..
    mine are two years old, and i notice already that they have not that punsh like 2years ago anymore - capacity on the other hand is nearly same
    (but i use the cells in high-current-applications.. on a bike that would maybe not that relevant)

    downside: this cells are NOT safe like Lithium Ion Mangan..
    in case of failure or mistake they will suffer "termal runaway" and start a fire..
    a 4900g lithium-fire ... well, i think you can say good by to your house with that !
    but with inteligent monitoring the risk are nearly close to zero (we all use the similar batts in our cell-phones, laptops, ... and not questioning: "will my house be there when i come back from work ?")
    so with monitoring and inteligent charger/equalizer/monitoring-systems risks are minimal

    here again: the batts are here for bikes with great distance.. the price :(

    the car-companies starting now (i think often only alibi-like) developing hyprid-cars with need also a (small) battery (think, that in next 5 years we will see a hyprid from nearly all companies)
    the need for big, good AND long-living batteries will raise a lot
    -> should hopefully bring price done, specially when there are more competitors on that sector
  17.  
    kraeuterbutter

    kraeuterbutter Just Joined

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    hmm.. iam realy wondering why they (the bike-companies) had such bad experiences with Lipo
    wereas i had that great success with that cells..

    it has made a revolution in my hobby, allowing things which were absolut unthinkable 5 years ago...
  18.  
    flecc

    flecc Member

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    Hello kraeuterbutter

    Powacycle are the first mainstream firm here to introduce Li-polymer, and have just introduced the LPX versions of two of their bikes, the Salisbury (gents) and Windsor (ladies) models. Here's the link to see the Salisbury and it's specification.

    It's interesting that this is one of the lowest powered bikes on the UK market, 26 volt with peak power of just 290 watts. That's half of the power of two of my eZee bike models, so an easy job for the battery. I don't think that's a coincidence!

    I'm going to guess that the eZee bad experience with experiments on Lithium Polymer is probably an issue of them being unable to deliver sustained current for their powerful motors. This is an issue with lithium ion in general on the more powerful e-bikes. Yes, I know that's not your experience on models, but it's definitely so with bikes. :)

    I hope you notice that this cynic does keep up with trends as this post shows. :D

    The need for the eZee models that I use is 36 volt with a minimum of 10 Ah, but preferably about 13 Ah, weighing the same or less than the present Li-ion manganese 4.4 kilos.
    .
    Last edited: Mar 1, 2007
  19.  
    allotmenteer

    allotmenteer Finding my (electric) wheels

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    Many of you regular posters will remember that I have suffered a thermal event to my li-ion. In my experience then 100% of these li-ions fail.:rolleyes: I don't know the exact chemistry of the battery though. I have returned it to the shop who have passed it on back to the manufacturer for testing. It may turn out to be faulty manufacturing or even the charger. I'll have to wait and see. In the meantime the shop are sending a replacement out.

    When I get the replacement it is not being stored in my house I can tell you! Certainly not in my fridge flecc, I don't want a sheet of flame coming at me every time I open the fridge to get a beer!:D
  20.  
    flecc

    flecc Member

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    Sounds like it could be good, dinner cooked straight out of the fridge. A Lithium Ion Cobalt fridge could make you into a millionaire!

    Dragon's Den anyone? :D
    .

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