Anywhere you need a small but longer lasting battery and don't care about mass. The primary issue with a larger mass is accelerating and decelerating it. However with the larger capacity, it would be less efficient but perhaps could still lead to longer range in the car if the extra energy stored overcomes the added cost of moving it around. Probably not a good thing but could be useful then in something like an electric race car or something.
Submersibles (which may not care about weight due to ballast anyhow), Batteries for Solar Storage (price dependent likely bad at first), Pacemakers, Hearing aids, once it's invented if robotics outpace man engineered human biology, maybe smart blood.
Perhaps also Nanobots, Active 3d Glasses, Cell phones, Laptops, Tablets, Smart Watches that go for smaller space vs weight.
Outside of that perhaps home appliances like a portable bread machine, or a hand-held wireless electric apple peeler, very small things like a rock that has a hidden microphone / camera in it for spycraft, perhaps a heated travel mug to keep your cider warm, or an electric bowl for keeping great-gravy from coagulating on the dining room table, maybe a warm pie plate because who doesn't like warm cherry pie? Perhaps some sort of autonomous mud tunneling microbots, rather have a large boring machine just let these small guys go and be patient and in a decade or two you'll have your tunnel, electric candles in churches could cut down on unnecessary wax use, and helmet lamps used for stuff like lead mining could also find a use (added neck strain not withstanding). Not sure if the added weight would be too much for a target-practice duck that swam around in a lake or not, but if not, that might be the right answer.
I think that in many cases, smaller but heavier with more power is a good trade-off. Think cell phones, cameras, bike lights, camping lights, laptops, etc. while lightweight is a feature for all of these, they're also useless without a charge, so IMO the battery life and size together are more important than weight as long as it's still reasonable. Glass isn't light at all, yet they use that a ton in phones. The iPhone 6S Plus is really heavy and I haven't heard anyone complain about it. The efforts around consumer electronics I've seen in the past 20 years have mainly been about reducing size, with reducing weight as a nice typical side-effect.
This would be really great if it ever hits production, but given past battery progress vs what's actually available, I'm not holding my breath.
> The iPhone 6S Plus is really heavy and I haven't heard anyone complain about it
A significant amount of that weight is the battery, so making the battery 2.5x heavier would make the phone substantially heavier, even with the same overall charge. You'd be hard pressed to sell someone on 'This new phone we made is great, you get the same battery life as before but it weighs 40% more!'
I suppose the question is, in which cases would people be willing to accept a lower charge capacity if their phone could charge to full in, say, minutes rather than hours? I feel as though those USB battery packs that are everywhere these days would be a great candidate; plug it into the wall for a few minutes and you're fully charged, and you can charge anything else from there.
Are you sure that wasn't to dampen vibrations which might affect (or even themselves be caused by) spinning the disk and movements of the read head? (Same reason there's concrete blocks in the base of a washing machine)
> electric candles in churches could cut down on unnecessary wax us
I know your comment is a bit tongue in cheek, but an LED connected to an AA battery is enough to last a few days - IKEA sell a nice set that even flickers. I don't go to church, but I suspect the flame (fire) itself is symbolic.
I wish I had a more pithy comment with which to reply, but I'll have to make do with just saying that was just hysterical. I hope you meant it to be so.
>The primary issue with a larger mass is accelerating and decelerating it
It's actually friction, for electric cars. Regen is pretty effective at recapturing acceleration, so the energy lost in the wheels is the biggest factor.
> It's actually friction, for electric cars. Regen is pretty effective at recapturing acceleration, so the energy lost in the wheels is the biggest factor.
Mass counts much. It's not just about accelerating a still object (car) out of friction. But it's also about working against gravity (g). If the car's acceleration vector is at some angle with gravity (ie, when not perpendicular), more energy will be required to accelerate (when climbing slops), and to break (down the slope).
This is very much clear for aircrafts, and other flying objects.
Edit: Inertia is also a reason for energy loss in cars (and other moving objects), which increases with mass.
Regeneration recovers a certain percentage of any energy put into speed or altitude. No matter how long you spend climbing you get a good fraction of that energy back. In practice this is pretty quick, and even in stop and go you spend more time at around the same speed than accelerating and slowing.
Rolling friction loss is related to speed and is occurring constantly as you drive. That energy is just gone immediately, unlike inertia, which is stored. Say you spend 50% of your time accelerating and braking, and 50% keeping speed. If you regen 80% of the energy and accelerate with 2.5x the power you use to cruise, you're using twice as much energy on friction as accelerating.
The parent mentioned regen and that electric cars are good at it. That means: you don't accelerate infinitely. At some point you decelerate, and then you can regenerate the electric energy. However long you drive uphill, eventually comes the downhill of equal length and you regenerate.
I don't know how good exactly electric cars are here, but considering that a Tesla can work as a taxi in the city, it must be pretty good.
Except for the risks inherent in large quantities of mechanical inertia stored in a rotating mass, flywheels might seem an attractive option for rapid energy exchange.
Not really. Acceleration is related to torque so jerk is the rate of change of current in the motor. Current in an electric motor goes from 0-100% ~10k times per second (PWM), so the motor doesn't notice much difference.
>Current in an electric motor goes from 0-100% ~10k times per second (PWM)
That's just the voltage across the terminals. The reason why this works is precisely because current doesn't go from 0-100% with the voltage. PWM is relying on the inductance of the motor to keep the current the same as it would be if the average voltage was applied across the terminals.
Submersibles (which may not care about weight due to ballast anyhow), Batteries for Solar Storage (price dependent likely bad at first), Pacemakers, Hearing aids, once it's invented if robotics outpace man engineered human biology, maybe smart blood.
Perhaps also Nanobots, Active 3d Glasses, Cell phones, Laptops, Tablets, Smart Watches that go for smaller space vs weight.
Outside of that perhaps home appliances like a portable bread machine, or a hand-held wireless electric apple peeler, very small things like a rock that has a hidden microphone / camera in it for spycraft, perhaps a heated travel mug to keep your cider warm, or an electric bowl for keeping great-gravy from coagulating on the dining room table, maybe a warm pie plate because who doesn't like warm cherry pie? Perhaps some sort of autonomous mud tunneling microbots, rather have a large boring machine just let these small guys go and be patient and in a decade or two you'll have your tunnel, electric candles in churches could cut down on unnecessary wax use, and helmet lamps used for stuff like lead mining could also find a use (added neck strain not withstanding). Not sure if the added weight would be too much for a target-practice duck that swam around in a lake or not, but if not, that might be the right answer.