[brettl]

I’m stealing this from the g01 forum. Someone posted this subject a while back and it turned out to be a great string. Hopefully it finds the same magic here!!

I’ll start with my dumb question- scientifically, is there a difference in a dc fast charge then from a level 2 slower charge? Aside from costs, speed etc.
Is a slower charge a better quality charge? More protons per atom type of thing?

[Paladin1]

For a variety of reasons, DCFC degrades the high-voltage Li-ion battery faster - i.e., it loses it's ability to retain and deliver a charge compared to its earlier "newer" state, usually expressed as capacity fade over time on a linear scale ("fast charging" does the same thing to your Li-ion household appliance batteries as well). Whether it's significant in the life cycle of the car needs more data (how much more degradation vs "slow" L2 charging, comparing identical batteries charged differently over months and years?). No essential difference in the chemistry of "charging," other than the speed of the reaction(s) and the additional generation of heat using more voltage, and it's effect on the internal components of the battery (a little more technical discussion than is warranted here). Suffice that "fast" charging is worse for the life/health/capacity of the battery, maybe a little worse, maybe a lot worse, depending.

[OB1Kenobi]

Charging is just a DC electrical current being applied to the cells, and current is simply electrons flowing across a conductor (wire). Assuming the incoming DCFC current is clean and ripple free, and assuming the onboard L2 charger is properly converting AC to clean DC, then one is not "better" than the other, just one provides a lot more current to charge the battery cells faster. As mentioned already, faster charging can have detrimental effects on battery performance and longevity. There could be minor overall efficiency differences between the two, but that's more a question of how much electricity you paid for versus how much was actually stored in the battery cells. The most efficient would be charging using DC from the source, such as directly from solar panels, but nobody seems to sell any systems that can do that.

[NomoTesla]

Per BMW's owner's manual, AC is preferred over DC as well as charging to a high SOC prior to departure versus letting the car sit. I keep mine charged to 50% for my daily driving needs. I rarely drive more than 100 miles in a day so that's plenty. Also, shorter charge cycles are better than long charge cycles. IOW I plug-in opportunistically and charge in under 5% increments usually. MUCH healthier for the battery to do 10x 5% charges than a 1x 50% charge.

Due to the need for AC-to-DC conversion, AC charging incurs some additional losses that DC charging does not. However, DC charging also likely activates the car's behemoth cooling system, which takes a chunk of power and also impacts efficiency. Not sure how the numbers pencil out on that.

[Windshieldfarmer]

Question…when using my home AC charger is there a difference to long term battery health if I charge at 30 amp vs 48 amp? I’m sure more heat is generated at 48 amp, but don’t know if it matters.

[exxxviii]

Originally Posted by Windshieldfarmer

Question…when using my home AC charger is there a difference to long term battery health if I charge at 30 amp vs 48 amp? I’m sure more heat is generated at 48 amp, but don’t know if it matters.

There is probably no material battery impact to charge rate on Level 2 charging. The key thing to remember here is that AC Level 2 charging is already so slow that small changes do not matter. The L2 "C Rate" is minuscule.

[jheitz]

The big problem with lithium batteries is that the membrane separating the two halves of the battery must be super uniform. If a hot spot develops, where the ions pass through, the hot spot attracts even more ions and gets hotter still. Sort of like how a tornado forms when a cold layer of air wants to break through the warm layer. This is why each cell has its own little computer to control the charging rate. Fast charging makes it more likely for those hot spots to form and basically destroy that cell.

[brettl]

On your sky-panel, when it’s in ‘clear mode’, do you still see a bit of cloudiness? Seems that if I’m not looking directly through (perpendicular to the glass)but off to an angle, it still seems to be a bit cloudy.
Others experience this too?

[LVBMW]

Originally Posted by brettl

On your sky-panel, when it’s in ‘clear mode’, do you still see a bit of cloudiness? Seems that if I’m not looking directly through (perpendicular to the glass)but off to an angle, it still seems to be a bit cloudy.
Others experience this too?

It's not as crystal clear as plain glass even in clear mode, yes. At least as far as I've noticed.

[Paladin1]

The iX sunroof/moonroof is laminated electrochromic glass and is slightly frosted even in "clear" mode, likely because BMW wanted to attenuate incoming visible light because of the expanse. It does do an excellent job of rejecting UV energy (reducing heat) and some IR radiation (also reducing heat). The windshield has a specific IR coating that rejects almost 99% of incoming IR.

[brettl]

Does anyone know what the output power on the usb-c’s is?

[brettl]

Is there a marked increase in efficiency driving the car in B vs D from anyone’s experience?

[darylp310]

Originally Posted by brettl

Does anyone know what the output power on the usb-c’s is?

The front ones do 15 watts, and the ones behind the seats do 45 watts.

https://bmwi.bimmerpost.com/forums/s....php?t=2043695

[ggalanis]

Originally Posted by brettl

Is there a marked increase in efficiency driving the car in B vs D from anyone’s experience?

In the iX, no. Two different ways to get the same results.

[Barry123]

Originally Posted by ggalanis

In the iX, no. Two different ways to get the same results.

That is true only if the amount of friction brake use is the same. If in D, you use the brake pedal more, you are losing energy to heat, rather than recharging.

[exxxviii]

Originally Posted by Barry123

If in D, you use the brake pedal more, you are losing energy to heat, rather than recharging.

This is true only if you exceed the amount of regen braking that the car can provide. But the same would happen in B mode - if you need to exceed the car's regen braking and you use the brake pedal in B mode, you would use the same friction braking as if in D mode.

[ggalanis]

Originally Posted by Barry123

That is true only if the amount of friction brake use is the same. If in D, you use the brake pedal more, you are losing energy to heat, rather than recharging.

Obviously to compare the two modes means driving and braking the same way. If in D you need to apply more brakes than just regen alone, you'd need to do the same in B mode, thus makes no difference.

[[DT]]

How would I go about making a half-man, half-monkey sort of creature?

[brettl]

Originally Posted by [DT]

How would I go about making a half-man, half-monkey sort of creature?

That’s over on the Tesla forum.

[AlanG]

What does an EVSE do? And why do do you need one? Could I just run a 50 or 60 amp line to the car?

[LVBMW]

Originally Posted by AlanG

What does an EVSE do? And why do do you need one? Could I just run a 50 or 60 amp line to the car?

Not sure i understand the question…

[AlanG]

Originally Posted by LVBMW

Not sure i understand the question…

For home charging you install a box that has a 40, 50, 60, 80 AC amp line in from the house and an out put line to car which will have the CCS NACSconnector on it. My understanding is that the box is generically called an EVSE, electric vehicle supply equipment. They are supplied be companies like Charge Point, Juice Box, Tesla, etc. My understanding is that the box sends AC power to the onboard “charger” in the car that converts it to DC power and monitors to charging process in the car. My question is what does the box in garage from some one like Charge Point do?