battery technology breakthrough?

[eddieo]

On the way to work tonight I heard on R4 something about a breakthrough in battery technology?

I was half asleep (as usual) So have looked it up on Goggle but can't find anything. They were saying it was a vast improvement on lithium etc.........

 

[lectureral]

Here you go:

Breakthrough battery can charge up in seconds - Times Online

Personally I am not too worried about recharging times - I generally do it overnight - but if they could reduce the price by a factor of 10 that would be good!

 

[Mussels]

It's a little early for my maths but to charge the Wisper battery in a minute would require something like a 130A mains supply.
There may be a flaw in their plan!

 

[UrbanPuma]

If this new technology proves successful, how will it affect the longevity of batteries for electric bikes?

 

[Mussels]

If this new technology proves successful, how will it affect the longevity of batteries for electric bikes?

I'm guessing it is aimed primarily at electric cars so won't offer much in the way of advancement for electric bikes. If it even works, these announcements seem quite common.

 

[Patrick]

It's a little early for my maths but to charge the Wisper battery in a minute would require something like a 130A mains supply.
There may be a flaw in their plan!

If it takes 10 - 20 seconds instead of 6 minnutes to charge a battery, then my calculations make the new charging time 2 - 3 minutes per hour of current charging time. So an 8 hour charge would be cut down to 16 - 24 mins at well under 13A.

Patrick

 

[wibble]

What's great about this is that if e-bikes become more popular then petrol stations may install a charger for us. No more having to worry about travelling long distances!. Woot!

 

[flecc]

Don't hold your breath, I'd like a £1 for every time I've seen MIT announcements about miracle breakthroughs.

These fast charging types that Toshiba have led the research into are intended for electric cars, enabling a fast charge during a trip. Most of these to date are unsuited for e-bikes since they have been larger and heavier for a given capacity.

e-bikes need the opposite, high capacity to weight and size with the charge time nor mattering much.
.

 

[rog_london]

If it takes 10 - 20 seconds instead of 6 minnutes to charge a battery, then my calculations make the new charging time 2 - 3 minutes per hour of current charging time. So an 8 hour charge would be cut down to 16 - 24 mins at well under 13A.

Patrick

High-speed charging isn't a new idea - in the early days of nickel-cadmium, you could get cells which could be charged at the rate of 10C - i.e. a 4 amp hour cell (some D cells were this capacity) would accept a charge rate of up to 40 amps. The trick was to cut off well below the full charge point, otherwise the cell would be destroyed by heat very quickly.

My brother used these to fly model aircraft - charged over seven or eight minutes from a car battery (with suitable resistor) he then would have around five minutes of flight. You needed to watch the time carefully, and the cells needed to be flat to begin with, so you knew where you were! Nicads are notoriously difficult to monitor for charge state.

Ageing nicads can sometimes be reawakened by this trick - but I can't recommend it as it's potentially dangerous (risk of explosion). As they say, may contain nuts, don't try this at home!

Rog.

 

[flecc]

And 60 years ago there was a sudden craze for fast charging car lead acid batteries, many garages set up for it. Basically the batteries were placed in a tank packed with dry ice to hold the temperature down while they were charged in half an hour or so. It wasn't a good idea and it soon disappeared.
.

 

[eddieo]

Oop's....I didn't realise it was just regards faster charging, although this woud be welcome while travelling......Just looking forward to large capacity light weigh batteries

 

[flecc]

Oop's....I didn't realise it was just regards faster charging, although this woud be welcome while travelling......Just looking forward to large capacity light weigh batteries

Oddly enough the lithium polymer batteries that are now on many of our bikes were originally developed by Toshiba as very fast charging batteries for future e-cars. They achieved the fast charge by having very low cell content density, therefore having greatly reduced capacity for a given weight and bulk.

That illustrates the inherent trap. A low density means low capacity but with fast charging and high current delivery rates, so no cutting out risk.

On the other hand, a high density means high capacity, but slower charging and worse still, slower current delivery rates which can starve high power motors if taken too far.

Basically the less there is in the cell, the easier it is for current to get in and out fast.
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