Kia Niro EV

Rusky rusky

Lumen wrote: »

No, it's junior cert science.

I'll give you a grossly simplifed example.

Say each cell is 3Ah, nominal voltage of 4V.

You want 72kWh capacity, so you need 6,000 cells.

In a 400V pack you arrange them into 100 modules of 60 cells. The modules are wired in series, and within each module in parallel. So each module sees 4V, and each cell sees 4V. At 100kW charging speed, the pack is passing 250A, each module also 250A, but each cell gets 4.17A.

In an 800V pack of the same design (modules in series, cells in parallel) you arrange the same cells into 200 modules of 30 cells. The modules see 4V, the cells see 4V. At 100kW charging speed, the pack is passing 125A, each module also 125A, and each cell gets 4.17A.

If you can think of a way to redesign the pack such that each 4V cell sees half the current whilst charging at the same C rate, then you've just broken the laws of physics as I understand them.

Again, the benefits of higher pack voltages are not realised at the cell level.

Higher current results in higher heat losses as per Joule's first law, also known as the Joule–Lenz law, it states that the power of heating generated by an electrical conductor is proportional to the product of its resistance and the square of the current. So at higher voltage you need lower current, hence lower heat losses.

Lumen

Rusky rusky wrote: »

Higher current results in higher heat losses as per Joule's first law, also known as the Joule–Lenz law, it states that the power of heating generated by an electrical conductor is proportional to the product of its resistance and the square of the current.

Yes.

Rusky rusky wrote: »

So at higher voltage you need lower current, hence lower heat losses.

Only if the resistance is the same. In practice, higher pack voltage tends to result in lighter wiring of higher resistance. Porsche have documented this in their promo materials for the Taycan.

AFAIK heat losses in the high voltage circuits are not a major issue in EVs.

And again, this is all irrelevant at the cell level (as Mad Lad pointed out before he started disagreeing with me ).

Lumen

Lumen wrote: »

(as Mad Lad pointed out before he started disagreeing with me ).

who what ? tell me I don't remember, I want to know my error lol. typing while working and trying to hide.....:D

Lumen

Deleted User wrote: »

who what ? tell me I don't remember, I want to know my error lol. typing while working and trying to hide.....:D

OK...

Deleted User wrote: »

800 volts won't matter, it's just different cell config to give 800 volts...800 volts just means less current needed to give more Kw, whether this impacts C rates is another matter for acceleration but I doubt it, the Kv rating of the motor + reducer gear ratio will determine overall acceleration.

and then

Deleted User wrote: »

Higher voltage means less current needs to be taken and put into the pack so for batteries with higher energy densities and lower power densities this would allow faster charging without the need for crazy high currents.

It also means less current is needed from the fast chargers reducing the need for more expensive power supplies to handle such currents and requiring liquid cooled cables.

Higher voltage means better efficiency.

So it will matter or it won't matter, but I think we agree that cell chemistry and cooling is the main gateway to faster charging, not 800V.

A Model 3 can charge at 250kW on 350V nominal (hence why it gets only 175kW at 500A Ionity chargers).

KCross

Lumen wrote: »

So it will matter or it won't matter, but I think we agree that cell chemistry and cooling is the main gateway to faster charging, not 800V.

I disagree with you anyway.

The 800V is part of the move to higher charge rates. Cell chemistry and cooling play their part of course in reducing/dealing-with excess heat but the 800V is an integral part of getting to the higher rates.

championc

Obviously, some hope that you'll be able to fill a car with power at almost the same rate as filling the tank of an ICE. But they don't allow for people having their own personal topup stations at home.

But on a long journey, people should leave time for an hour stop after 3 or so hours, and in Ireland, about 45mins topup after starting the day on a full charge, should be enough to get anyone to their destination

Kramer

KCross wrote: »

I disagree with you anyway.

I concur with Lumen on this one - 800v has advantages but higher voltages ubiquitously help with transmission losses.
Individual lithium cells can't take more than 4.1v or 4.2v. It won't matter whether that is derived from 400v or 800v. The advantage comes from the increased power capacity of the system with higher voltage.

Think of it (800v) as being able to charge two identical battery packs (400v) simultaneously. You'll ultimately end up charged twice as fast, but each lithium cell will never know anything other than 4.1/4.2v.

championc wrote: »

in Ireland, about 45mins topup after starting the day on a full charge, should be enough to get anyone to their destination

Assuming an available fast charging hub ideally placed, yes.
12 or 15 such hubs, well placed, with a quick charging 50kWh+ car, is all that's realistically needed in Ireland (plus home charging, destination charging etc.).

unkel

Kramer wrote: »

I concur with Lumen on this one - 800v has advantages but higher voltages ubiquitously help with transmission losses.

Not just less transmission losses, the hardware is much cheaper too. From the cabling and other components in the car to the components in the charge point.

I.e. for a 180kW charger @900V needs just 200A (probably no liquid cooling needed) and the same power charger @450V needs 400A (deffo liquid cooling needed)

championc

Kramer wrote: »

Assuming an available fast charging hub ideally placed, yes.
12 or 15 such hubs, well placed, with a quick charging 50kWh+ car, is all that's realistically needed in Ireland (plus home charging, destination charging etc.).

The use of 50kw chargers seems to be minimal now that that power is chargable. As time goes by, all motorway (and just off the side) service stations will likely gradually add units to forecourts

KCross

Kramer wrote: »

I concur with Lumen on this one - 800v has advantages but higher voltages ubiquitously help with transmission losses.
Individual lithium cells can't take more than 4.1v or 4.2v. It won't matter whether that is derived from 400v or 800v. The advantage comes from the increased power capacity of the system with higher voltage.

Think of it (800v) as being able to charge two identical battery packs (400v) simultaneously. You'll ultimately end up charged twice as fast, but each lithium cell will never know anything other than 4.1/4.2v.

I understand that the cells are configured differently(series vs parallel) in 800v vs 400v and are ultimately much the same at an individual level.


I dont get the explanation how the cells are getting the same current in both these cases, which Lumen says they are..
- 800V pack with 100kWh capacity receiving 200kW
- 400V pack with 100kWh capacity receiving 200kW




Let me add a quote from Joachim Kramer, Porsche’s director of power electronics for the Taycan!...

“At the moment, on a 400-volt car, the charging connector is the bottleneck for the charging power,” said Joachim Kramer, Porsche’s director of power electronics for the Mission E and other electric-vehicle projects, summarizing the issues in an interview with C/D. As it turns out, that holds true all the way to the cell level. “Putting the cells in sequence—so, doubling the voltage—you could really get the full use of the battery cell and get a higher charge rate, because then the connector isn’t the limit.”

And that’s shaping up to be the Mission E’s ace card. Porsche doesn’t have (or need) any lock on special, game-changing battery-cell technology or a radically different chemistry to accomplish this. By using cells that are configured in parallel in 400-volt systems, but instead mounting them in series, Porsche has found an elegant solution that’s more than a workaround. Mounting them in sequence means you need double the voltage but half the current at the same input power. “Having the same cells as the 400-volt cars, we now operate at the battery limits,” Kramer asserted.

In addition to charging times, Porsche says the 800 volt system theoretically yields more efficient power transfer and allows for thinner wiring, since for a given power output, a higher voltage system sends less current, and it’s current that generates lots of heat in wiring (losses go up with current squared). “It’s simply more efficiency in the complete high voltage system,” said Porsche’s electronics guru.

My understanding is that the 800v system was devised so that they could drop the current across the entire system... not just the cables on the charger (which was also a limitation).

You can theoretically increase the current through existing cells in a 400v system and get to 350kW but it'll fry the cell. Increase the voltage of the pack to 800v, half the current and now you can get to 350kW without frying the cell. That was my understanding of it.

I need to dust off my power electronics books!

Lumen

Those connector limits occur way higher than the 70kW max of the Kona, like over 150kW. This is why Kia are proposing to use 800V only for the premium models.

I look forward to your electronics revision bearing fruit so you can explain Porsche's "all the way to the cell" argument. I know my limits!

KCross

Lumen wrote: »

Those connector limits occur way higher than the 70kW max of the Kona, like over 150kW. This is why Kia are proposing to use 800V only for the premium models.

I look forward to your electronics revision bearing fruit so you can explain Porsche's "all the way to the cell" argument. I know my limits!

I'm not putting myself out there as a match for Porsche’s director of power electronics! I know my limits too!

liamog

The CCS connector is rated for 500A / 1000V DC. If you want to charge at > 200kW you have to increase the pack voltage.
Higher current requires thicker cables, so keeping the current low by increasing the voltage allows you to use smaller (cheaper) cables throughout the car.

Busman Paddy Lasty

KCross wrote: »

I'm not putting myself out there as a match for Porsche’s director of power electronics! I know my limits too!

I'm not qualified to disagree with Kramer. He works for Porsche and is a knowledgeable Boardsie in his spare time!

Can anyone recommend a power electronics book, from experience, that would be helpful to an EV driver? This is interesting but very new and confusing to myself.

All that matters to the battery is the C rate at which it's charged and discharged and the voltage, do not exceed these limits and it's happy.

ELM327

liamog wrote: »

The CCS connector is rated for 500A / 1000V DC. If you want to charge at > 200kW you have to increase the pack voltage.
Higher current requires thicker cables, so keeping the current low by increasing the voltage allows you to use smaller (cheaper) cables throughout the car.

Agree. If you look at how manufacturers (note - Tesla are a specific exception as they are operating over the 500A limit for their "ccs" proprietary chargers) are exceeding 200kW it's in 800V packs (Taycan)


Tesla allow 670A charging using their CCS chargers. This is why TM3 can get 250kW peak at a SuC v3 but is "peaked" at 190kW at Ionity

xboxdad

LEVTI topic:

I just converted my video account on eFlow to a tag account.
I don't see an option to mark my e-Niro a BEV or to tell eFlow it's eligible for LEVTI rates.
How will eFlow know to charge LEVTI rates without me flagging the car as eligible/BEV/etc...?

Thank you.

unkel

Cancel eFlow and move to tolltag.ie / parkmagic. eFlow is a mess and the EV debate is chaotic, you won't get it until the end of the month, if you get it at all.

With tolltag.ie / parkmagic, the discount is immediate. Costs €1.21 per month but the M50 toll alone saves €3.16 for each return trip off peak, so with just 5 return trips per year, you are in the money with the toll tag.

xboxdad

unkel wrote: »

Cancel eFlow and move to tolltag.ie / parkmagic. eFlow is a mess and the EV debate is chaotic, you won't get it until the end of the month, if you get it at all.

With tolltag.ie / parkmagic, the discount is immediate. Costs €1.21 per month but the M50 toll alone saves €3.16 for each return trip off peak, so with just 5 return trips per year, you are in the money with the toll tag.

Thank you, but you can only close the eFlow account via contacting customer service.
The reason I'm asking you guys here about how LEVTI works in the first place is because eFlow customer service is closed during the pandemic. Got the same reply via both Facebook and email.


...and you have to return all tags which they're just about to send me because I converted my account.

So it's not quite feasible for me to close that account for the foreseeable future.
Going to have to try eFlow and see how it works I guess, at least for a couple of months.


Do you have any info on my original question? It doesn't seem I'm going to get any from eFlow this side of Halloween.

Silent Running

xboxdad wrote: »

LEVTI topic:

I just converted my video account on eFlow to a tag account.
I don't see an option to mark my e-Niro a BEV or to tell eFlow it's eligible for LEVTI rates.
How will eFlow know to charge LEVTI rates without me flagging the car as eligible/BEV/etc...?

Thank you.

From memory... I had to ring them and the guy on the phone said that it had to be handed to "the team" dealing with this as the car had to be verified as qualifying. I got an e-mail a few days later to tell me that it was done.

If you can't contact them by phone.... I dunno.

xboxdad

Silent Running wrote: »

From memory... I had to ring them and the guy on the phone said that it had to be handed to "the team" dealing with this as the car had to be verified as qualifying. I got an e-mail a few days later to tell me that it was done.

If you can't contact them by phone.... I dunno.

Oh I'll try the phone so
Thanks!

unkel

xboxdad wrote: »

Thank you, but you can only close the eFlow account via contacting customer service.
The reason I'm asking you guys here about how LEVTI works in the first place is because eFlow customer service is closed during the pandemic.

Another reason to ditch them. I changed EV during the lock down and I was able to add my new car to my account with tolltag.ie / parkmagic online myself and the EV status (with the discounts) came up as approved when I checked about a day later

championc

You have to notify them of the change - they don't apply anything automatically. I have eFlow and they were prepared to honour the discount once I had proof of contacting them, and would only honour it from that date. So I had change the car on the portal but never contacted them until I'd made a few trips, so the first few were at full price.

But I contacted then in early April, which was right in the eye of the storm at the time. I contacted them on Twitter - @eflow_freeflow

social butterfly 2020

Where does one place the eflow tag on the niro?.

xboxdad

I'm looking for a lumbar support solution / cushion available locally. Did you guys try any of the Argos or Halfords ones? I'm wondering which ones fit the e-Niro seats properly.

Update: I just reserved this, I hope it'll work well: https://www.argos.ie/webapp/wcs/stores/servlet/ProductDisplay?storeId=10152&catalogId=15051&langId=111&productId=1016128

Krusty_Clown

social butterfly 2020 wrote: »

Where does one place the eflow tag on the niro?.

For our tolltag, we placed it just to the left of the rear mirror stalk, just below the dark shading - where it doesn't obstruct the driver's vision (hidden by the mirror).

chewed

Krusty_Clown wrote: »

For our tolltag, we placed it just to the left of the rear mirror stalk, just below the dark shading - where it doesn't obstruct the driver's vision (hidden by the mirror).

I also have a dashcam I'd like to move into my new Niro, as well as the tolltag, so I hope there's room for both!

xboxdad

Krusty_Clown wrote: »

For our tolltag, we placed it just to the left of the rear mirror stalk, just below the dark shading - where it doesn't obstruct the driver's vision (hidden by the mirror).

The eFlow tag installation tutorial says it needs to be installed inside the dark/dotted area. May I ask why you installed it below that area?
I'm waiting for my tag to arrive & collecting info in the meantime.

Thank you.

tk123

chewed wrote: »

I also have a dashcam I'd like to move into my new Niro, as well as the tolltag, so I hope there's room for both!

I have both on the left. I had awful probs getting my front camera to stick to the windscreen in the hybrid though and ended up using 3m Dual Lock tape. I have more ordered from amazon.. as well as my silver paws to go on either side of the numberplate :P

social butterfly 2020

xboxdad wrote: »

The eFlow tag installation tutorial says it needs to be installed inside the dark/dotted area. May I ask why you installed it below that area?
I'm waiting for my tag to arrive & collecting info in the meantime.

Thank you.

the thing is in my eniro there is no dark/dotted area. what is there however is some sort of black plastic casing. so no where to put the tag. as can be seen in screenshot