New battery technology on the way?

[Mrke]

ScienceAlert.com - LINK:

Researchers have come up with a lithium ion battery that charges to 70 percent in just two minutes, lasts 10 times longer than today’s batteries and will reportedly be available within two years.

Snake oil or panacea?

 

[Mrke]

Opps, duplicate post, sorry : http://www.pedelecs.co.uk/forum/threads/is-this-new.19234/

 

[mike killay]

Probably true, but only under totally impracticable circumstances.
My rough calculation suggests 45 amps at 240 watts for a 360 w/h battery.
Most likely wrong but I am sure that one of our gurus will come up with the right figure.

 

[mfj197]

It's roughly 180 amps, 7.5kw for the 2 minutes.

70% of 360Wh is 252Wh. That is 15,120 Watt minutes, or 907,200 watt seconds, otherwise known as joules (energy). To provide that energy in 2 minutes (120s) you need to provide 7,560 joules/sec, i.e. 7.5kw. Assuming 42V charging gives you 7560/42 = 180 amps.

Michael

 

[trex]

if you want to charge your average 36V 10AH battery in two minutes at 70%, that will require 7A * 30 = 210A charging current, at 42V that will require a 8.8KW feed. It's doable but not indoors, unpractical as Mike said.
The more sensible approach is to use fuel cells. One litre of petrol or equivalent can produce about 10KWH of electricity, enough for 1,000 miles of assisted riding without the noise and fumes. That's one refuelling a year for half of us.

 

[Geebee]

But it would be a case of maximum charge rate, so inthe case of Oz 240v times 10 amps which is a 2.4kw
Or roughly 66.66 amps into a 36v pack say sub 10 minutes allowing for inefficiency, but not allowing for taper etc.
Charge time is not really a worry for my use anyway but 10 times longer life would be, I would be 6 feet under by the time the battery needed replacement

 

[trex]

even with current technology, the life expectancy of the electronics (BMS) is shorter than that of the Lithium ion cells. Most of the time, your battery dies because the BMS fails. The bike is exposed to weather, humidity gets inside the battery and corrodes surface mount electronic components.

 

[mfj197]

even with current technology, the life expectancy of the electronics (BMS) is shorter than that of the Lithium ion cells. Most of the time, your battery dies because the BMS fails. The bike is exposed to weather, humidity gets inside the battery and corrodes surface mount electronic components.

I don't think that should be the case though. Cars are often outside for many years and have considerable electrical circuitry to fail. I've never known a BMS fail and I've used Li-ions outside for many years - but I've never had an e-bike before.

Michael

 

[trex]

corrosion happens whenever you have two different metals that are shorted by humidity like in the picture below, taken inside a car:

The same thing happens at the charging port of any e-bike battery.
You don't need that much corrosion to kill a BMS.
Plus, you have copper, tin and lead in any electrical circuit. Potting is the only way to keep corrosion away.

 

[Geebee]

Trex, any facts to back that up?

 

[trex]

I took the picture below from a dead battery made in 2011. Note the corroded screw and PCB at the bottom right corner. Humidity condensed inside the casing, attacked the screw then shorted out the battery meter. The battery was completely drained last winter. The pack is unrepairable.

 

[mfj197]

Where did you keep the pack? Not indoors? Mind you, I've kept a 2S2C pack permanently on my bike for the last 3 years for my bike lights and it's absolutely fine. The bike is carried on the roof of the car twice a day at motorway speeds through all sorts of weather and lights, and battery pack, work as well as ever.

Michael

 

[Geebee]

But you imply that is the normal failure mode not a one off here and there.

I can take a picture in the morning of the original terminals on my 18 year old car (like your above photo) to show as a one off example that corrosion doesnt occur

 

[trex]

if you look at life expectancy, then factors like number of points of failures are important. In my example, the failure was due to a stainless screw that was not plated well enough, got corroded then the rust caused humidity to short the screw to the PCB where it joined steel to copper and spread the corrosion. The cells we have now can easily work for 10-20 years if the electronics does not fail, albeit whose failure was due to a rusty screw.

 

[Gubbins]

As I see it what's needed is a cheap light battery that will give out more energy for a longer time.. How long it takes to charge seems erelevant..

 

[mfj197]

The cells we have now can easily work for 10-20 years if the electronics does not fail, albeit whose failure was due to a rusty screw.

No they don't. We have lithium ion batteries in use everywhere, from mobile phones to laptop computers to rechargeable power tools to e-bikes. The cells' useful lifespan is normally about 3 years or so, dependent upon chemical composition. The cells gradually lose capacity - this isn't an electronic failure. An electronic failure causes something to suddenly stop working, not gradually reduce capacity.

 

[trex]

the reason that laptop and mobile phone batteries lose their capacity in 3 years is because we keep charging them all the time, even every day. Some e-bike batteries made in 2008 are still running now, 6 years on.

 

[mfj197]

the reason that laptop and mobile phone batteries lose their capacity in 3 years is because we keep charging them all the time, even every day. Some e-bike batteries made in 2008 are still running now, 8 years on.

Using what chemical technology? And keeping li-ion cells topped up is actually good for them and extends their life.

 

[trex]

current batteries use Lithium intercalation. Perhaps soon we'll see Lithium alloy then fuel cells.

 

[mfj197]

I meant what chemical technology is used in the 2008 e-bike batteries you mention as still going? Some technologies do work for longer; for example Toyota have never had to replace the nickel metal hydride batteries in any Prius even though they've been making them for 17 years.

Michael