Are we on the brink of an electric car revolution?

Post by **kenneal - lagger** » 25 Mar 2018, 15:49

vtsnowedin wrote:I expect that they will make considerable progress in both the construction and operation of battery packs to greatly reduce the number of rouge or dead cells. The whole pack will age together gracefully and be of little use once it can no longer move the car.

It's not a case of being able to move the car its the distance it can move it. Once that starts to drop there comes a point where it is "economic" (hate that word) to replace the battery.

Pepperman · Post by **Pepperman** » 25 Mar 2018, 17:21

Mr. Fox wrote:I guess he's getting them wherever he can - the Tesla model S used 18650s.

As I understand it, the Teslas (and other EVs) using Li-Ion cells don't incorporate balanced charging of the cells in the design... My own experience - mainly with electric bike batteries - is that a pack can fail because half a dozen of the cells are bad, whilst the rest are perfectly serviceable.

I had a recent 24v 10Ah pack, (35 x 18650s, 5P/7S) all but 5 cells tested held >90% of their rated capacity (of 2000mAh)... again, no balancing. Considering the manufacturer charge ~Â£400 per pack, I thought this was a bit tight of them, but if it lasts beyond the warranty period, I guess they don't really care. Good news for us 'recyclers', though.

(I reckon I'm going to need a low-voltage spot welder soon, so I'm keeping my eyes peeled for a scrap microwave).

No idea where you'd get hold of big 2nd hand EV batteries in the UK, though - with only ~13,500 new registrations of plugin EVs last year, I guess it's not a 'mature market'... yet!

EVs will all have a BMS. I don't think it's possible to safely charge large lithium-ion batteries without them.

vtsnowedin · Post by **vtsnowedin** » 25 Mar 2018, 17:22

kenneal - lagger wrote:
vtsnowedin wrote:I expect that they will make considerable progress in both the construction and operation of battery packs to greatly reduce the number of rouge or dead cells. The whole pack will age together gracefully and be of little use once it can no longer move the car.
It's not a case of being able to move the car its the distance it can move it. Once that starts to drop there comes a point where it is "economic" (hate that word) to replace the battery.

I was being a bit taciturn in omitting satisfactory or properly after" move the car". If it can't complete the whole trip then a shorter movement would be of no use.

Potemkin Villager · Post by **Potemkin Villager** » 25 Mar 2018, 19:31

PS_RalphW wrote: Cold weather performance improves in models like the Hyundai ioniq which has active battery teperature control.

Just spotted this.

"Active battery temperature control"

To me this sounds like something straight out of a sales brochure!

Is any clue given to where the energy comes from to power this active battery temperature control I wonder?

Mr. Fox · Post by **Mr. Fox** » 25 Mar 2018, 21:25

Pepperman wrote:EVs will all have a BMS. I don't think it's possible to safely charge large lithium-ion batteries without them.

Yes, very true all have a Battery Management System, but not all BMSs do charge balancing - many (most) simply monitor individual cells or parallel cell group voltages and cut charging/draining for the whole pack when one cell or group is full/empty. All things (cells) being equal, this is OK... it's when they aren't that the fun starts.

I read this on the Tesla forum:

We can not "balance" our battery packs! Balancing is done cell by cell. The battery management system in the Tesla is not set up cell by cell. All that happens when we "fully charge" and "full discharge" is we reset the counter that estimates the level of charge. That's right we don't really know how much charge is in the battery. We can only measure how much is put in and taken out. The algorithm makes little mistake over time because of short charging...

( Anthony J. Parisio | April 3, 2015)

https://forums.tesla.com/forum/forums/f ... ncing-pack

The bike batteries I've been working with certainly don't have a BMS capable of balanced charging... exactly how much this impacts the useful life of the pack is something I'd be keen to see any real-world data on.

-

"Active battery temperature control" sounds like "doesn't deliver as much current when the battery's getting hot" - hence the "improved cold weather performance"...

Engineer: "Shit. It slows down in hot weather!"
Sales team: "Heh... I know..!"

Potemkin Villager · Post by **Potemkin Villager** » 25 Mar 2018, 21:46

Mr. Fox wrote: be keen to see any real-world data on.

-

"Active battery temperature control" sounds like "doesn't deliver as much current when the battery's getting hot" - hence the "improved cold weather performance"...

Engineer: "Shit. It slows down in hot weather!"
Sales team: "Heh... I know..!"

Mr Fox ye sound an even bigger marketing cynic than me,

Pepperman · Post by **Pepperman** » 27 Mar 2018, 10:55

Interesting.

Potemkin Villager · Post by **Potemkin Villager** » 29 Mar 2018, 20:54

Then there is the issue of where the materials for the batteries comes from.

https://www.amnesty.org/en/latest/news/ ... practices/

" A key component of the rechargeable lithium-ion batteries on which electric cars run is cobalt. More than half of the worldâ€™s cobalt comes from the Democratic Republic of Congo (DRC). Despite its mineral riches, the DRC is one of the poorest countries in the world, and has suffered from decades of war and corrupt leaders. With so few formal jobs in the country, hundreds of thousands of Congolese men, women and children, have been driven to dig their own mines to earn their livelihoods."

Potemkin Villager · Post by **Potemkin Villager** » 04 Apr 2018, 20:13

https://www.facebook.com/skynews/videos ... 1_rjYVFIbI

More on the reality of cobalt mining. Have a nice day.

Post by **adam2** » 04 Apr 2018, 22:02

Potemkin Villager wrote:
PS_RalphW wrote: Cold weather performance improves in models like the Hyundai ioniq which has active battery teperature control.
Just spotted this.

"Active battery temperature control"

To me this sounds like something straight out of a sales brochure!

Is any clue given to where the energy comes from to power this active battery temperature control I wonder?

IME, "active temperature control" is not that sophisticated and uses very little energy.
When the battery is being charged it will become warmer due to the losses in the battery. When it is about to become warmer than it should, then a fan forces air between the battery cells to cool them. Sometimes an anti-freeze solution is used and cooled by passing through a radiator.
The only energy used is for fans and maybe a pump.

In some climates a fully charged battery may become too cold if left charged but unused for a few days, in these circumstances, electricity from the charging supply is used to keep the battery warm. This is only needed in climates so cold that FF vehicles parked in the open need engine block heaters.

When the battery is being discharged, heat is again produced, and a thermostatically controlled fan or liquid cooling system removes the excess heat so as to keep the battery at an optimum temperature.

woodburner · Post by **woodburner** » 28 Jun 2018, 20:54

BP has just bought a charging technology company for Â£130m. The company have been working on fast charging and claim to have some 150kW chargers which will charge 100 miles in 10 minutes. a spokesman said there would be no problem with electric cars as the grid already exists with abundant supplies of electricity. He obviously hasnâ€™t seen gridwatch in the winter.

Potemkin Villager · Post by **Potemkin Villager** » 26 Jul 2018, 18:01

woodburner wrote:..... 150kW chargers which will charge 100 miles in 10 minutes.........

They sound deadly!

Potemkin Villager · Post by **Potemkin Villager** » 31 Jul 2018, 22:01

We seem to be pretty much as far as we can go with Lithium batteries and limits on raw materials even at the present boutique level of up take.

https://www.nature.com/articles/d41586-018-05752-3

I think the dream of widespread uptake of EVs will never materialise.

woodburner · Post by **woodburner** » 01 Aug 2018, 01:12

Such blasphemy PV. Those and similar statements will be met with merciless attack, even on this forum. However, I think you are probably right.

emordnilap · Post by **emordnilap** » 01 Aug 2018, 12:27

"The advancement of the arts, from year to year, taxes our credulity and seems to presage the arrival of that period when human improvement must end." - Henry Ellsworth

Hmmm.