Battery breakthroughs

Discussion in 'General' started by Domenick, Oct 7, 2017.

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  1. Martin Williams

    Martin Williams Active Member

    Presumably greater ionic mobility = lowered resistance = lowered heat = quicker charging. This is nice, but its only of use if it doesn't degrade things like energy density, temperature tolerance, ageing, cost etc. We'll have to wait to see if it does
     
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  3. Energy density degradation occurs at the electrodes, not the electrolyte. Performance in a variety of temperature, aging and cost is always a concern.
     
  4. Martin Williams

    Martin Williams Active Member

    Well, that's one parameter we won't have to worry about, perhaps.

    I'm all for better batteries by the way. I use them too, albeit not in cars, but I'd like a smartphone which I don't have to constantly charge for starters. Or one I can charge in under a minute.
     
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  5. If I avoid whole discharge, if get maintain each time a minimal in 70% in charge, and all time maintain the temperature in 21º, this will extend the lifespan at a maximum, no ?
    If the vehicle has in the driver panel a gauge indicating the level charge, the driver can stop when the level fall under 70%, this can be a good use, no ?
    And as the vehicle is a electric motorhome, can have a pitstop, enjoy the surroundings...
     
  6. Martin Williams

    Martin Williams Active Member

    You are suggesting using only 30% of the battery's capacity. The main disadvantage is that this will not take you very far, and you will have to make frequent stops on a journey of any length.

    You will need to have a charging point at any 'pitstops' you make too, which limits the number of places where you can stop. The surroundings won't necssarily be very enjoyable...
     
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  8. but, dear martin. consider this:
    my charging point is anywhere, because I will get power from a set of 15 solar panels mounted on the roof - 5 fixed, more 5 on each sliding frames, for open when stationed. when, my charging plug is the sun...
     
  9. Martin Williams

    Martin Williams Active Member

    Well you are limited to travelling no further away from your roof than 15% of the battery's capacity if you want to use only your roof AND to never let the charge fall below 70%. How much this is in miles depends on your car, and whether you have the heating/aircon on of course, but if your lifestyle is not affected by these limitations then I guess you are happy with it, and good luck to you.
     
  10. Jim J Fox

    Jim J Fox Member

    Last edited: Mar 18, 2018
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  11. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    No. Maintaining a 70% or greater charge will not at all help extend battery life. In fact, you should avoid charging above 80% unless you need to for practical reasons.

    To maximize battery life, what you want to aim for is to have the mid-point of each charge and discharge cycle be as close to 50% as possible. Ideally that might mean, for instance, that you would charge to 80% and discharge to 20%, or charge to 70% and discharge to 30%, or charge to 60% and discharge to 40%.

    Of course, limiting the charge and discharge in this manner will also significantly reduce the range of the vehicle, or -- if the battery pack is being used to power the lights and appliances in an RV -- the number of hours of battery life before you need to recharge.

    The rule of thumb for home solar power users with stationary li-ion battery storage is an 80%/20% charge/discharge cycle. If you're using your battery pack to power your RV when it's parked, then I suggest you aim for that to extend battery life.
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  13. Martin Williams

    Martin Williams Active Member

    All more hassle than I want I'm afraid. I don't see that this sort of battery nannying can be conveniently dumped off into a microprocessor to handle very easily either. I have a lot of things in my life much more interesting to think about than the state of my car battery I'm afraid.

    However, if you are interested in your battery and happy to monitor it, far be it from me to stop you doing so.
     
  14. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    That fits in perfectly with your prediction that no more significant advances will be made in battery tech, Martin. Both predictions will be proven wrong pretty shortly.

    When driving a Model T Ford, when accelerating or decelerating, one must manually advance and retard the spark lever in addition to working the accelerator pedal. That's something that "early adopters" in the motorcar revolution had to put up with.

    Having to manually deal with the charge level on an EV, and the Depth of Discharge, is something which we can reasonably expect to disappear just as rapidly as the manual spark advance lever did. If there's not yet an app for setting EV charge levels, we can be confident there soon will be!
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  15. Martin Williams

    Martin Williams Active Member

    Well despite having a wide choice of models, and charging points everywhere, 98 out of 100 car buyers prefer ICEs at the moment.

    My explanation is that battery nannying is no more attractive to the general public than it is to me. If you have a better explanation then that's just fine.
     
  16. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Must be some other "Martin Williams" who keeps asserting that there will never be EV charging points everywhere. :rolleyes:
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  17. Martin Williams

    Martin Williams Active Member

    Must be as I said no such thing.

    Possibly at some future date batteries might be almost as hassle-free as a fuel tank! Sadly they are nowhere near that happy state yet! In all battery powered cars that you can buy now, you DO have to worry about it or live with an expensive battery replacement at some stage. And I count a smartphone telling me to charge the battery no less hassle than a red light on the dashboard doing so.

    I'd be really interested to hear your theories as to why the public seem so unimpressed by the wonders of battery cars though.
     
  18. Ok, well, this is interesting. Sion Power (a company I've been tracking since the mid-2000's) have said they will start producing a 500 Wh/kg battery this year.
    I said, THIS YEAR. Ok, so it's not the perfect battery, as cycle life takes a hit, but that energy density is pretty awesome.
     
  19. Martin Williams

    Martin Williams Active Member

    Well, I wish it well, but I think the poor cycle life will probably rule it out for most applications.

    Its unfortunate, but batteries have to be acceptable in so many ways simultaneously. I suppose it might have military applications where high energy density is more important than cycle life, however, such as drones. (A long cycle life is superfluous if it's almost certain to be destroyed by enemy action within a few days)
     
  20. It could work in EV applications as well. End of cycle life is usually calculated as 80% of initial capacity.
    So, if I had a car with a 100 kWh battery, giving me 500 miles of range, I'd only ever have to fill it once a month, if I was commuting regularly. So then, that 450 cycle rating means it would take me 37.5 years to drop down to 80% capacity, if no other degradation factors were in play.
     
  21. Martin Williams

    Martin Williams Active Member

    Point taken. I hadn't looked at it that way.

    I wonder who the first car manufacturer to take advantage of them will be?
     
  22. My calculations above weren't especially conservative, but even 1/3 of of that, 12 years to 80%, would be acceptable for many vehicles.

    I think that, although they mention EVs, I would be surprised to learn that they already have a supply contract with an automaker. It would take quite a bit to scale up production to many thousands of kWh needed for a single, not-especially-popular model. If they were to try a smaller boutique-type maker like a Bollinger Motors or Arcimoto or something, then I think cost and/or scale might be an issue, as those companies would be too small to sign a large enough contract to allow Sion to get its suppliers on board (because of banks/letters of credit, etc).

    So, maybe batteries for drones (no doubt the department of defenses would be interested) or other smaller devices. Actually, depending on other properties, a motorcycle might work out quite well.
     

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