02-29-2020, 09:56 AM | #23 | |
Colonel
1091
Rep 2,420
Posts |
Quote:
So if you program your trip you shouldn't have to use battery hold. If you are not able to charge at your destination you can also program the return trip. The car will program battery use so that it should be nearly empty on arrival back home and maximal use of the battery in the city. |
|
Appreciate
1
volodp196.50 |
03-03-2020, 01:59 AM | #24 | |
Private First Class
98
Rep 183
Posts |
Quote:
|
|
Appreciate
1
menace3346.50 |
03-03-2020, 02:42 PM | #25 | ||
Colonel
1091
Rep 2,420
Posts |
Quote:
|
||
Appreciate
0
|
09-04-2020, 03:48 AM | #27 |
Private First Class
47
Rep 108
Posts |
IMO, the main benefit of electric driving is in its quietness. So, I tend to use electric driving in the city and below 80kmh. Above 80kmh, the wind resistance is more loud than the engine noise.
|
Appreciate
1
volodp196.50 |
09-28-2020, 05:48 PM | #30 |
Major General
3159
Rep 6,799
Posts |
In my i3, whose max acv charging rate in the USA is 7400W, it uses two modules to convert to the DCV needed for the batteries. I'm pretty sure that the 45e is just using one of those modules, so there is no software ability to upgrade the charging rate. Keep in mind, this is a dc power supply and the internal components and the wiring gage involved all needs to match up along with the management of the heat involved in the process. From what I have read, the 120vac charging is less efficient than the 240vac level where the 240vac efficiency is in the order of 95%. So, from an efficiency viewpoint, going to a level 2 EVSE makes some sense in addition to the faster speeds.
Power = volts * amps, and the amps in any of the inputs is limited to 16 for the 45e, so doubling the voltage (and in the US case, raising the amperage to 16 from the supplied 10A devices supplied) will more than triple the charging rate. In a typical garage, a 120vac receptacle may be shared with lights, the garage door opener, and who knows what else. As a precaution, to prevent popping the circuit breaker, the default charging rate is 6A. If you have a dedicated circuit, or are sure that 10A won't pop the breaker, there's no down side to bumping the car's menu up to 16A which is also the maximum you could charge on 120vac if it were a 20A circuit (the 80% rule applies for a device like this). |
Appreciate
0
|
09-29-2020, 08:52 PM | #31 | |
Private First Class
44
Rep 165
Posts |
Quote:
If the car has 17kWh usable battery (US) and you are saying 3.7kWh wouldn't this be ~ 4.5 hour (by math)? Let say you have a charger at home rated at 40a: 240v * 40 amp = 9600 watts capable Even though I have 9.6kW I can only charge at the rate of 3.7kW but this still would be 4.5 hour no? Where is my logic wrong? Unless after 80% rate slows down? Also with 3.7kW charge we don't need anything more expensive than 16a charger correct? 16*240=3840 watts > 3.7kW 45e
__________________
f25@110K and counting...
Last edited by ketrab; 09-29-2020 at 09:03 PM.. |
|
Appreciate
0
|
09-29-2020, 10:28 PM | #32 | ||
Colonel
1091
Rep 2,420
Posts |
Quote:
On 3,7 kWh in Europe charging to the 20,9 kWh to 100% takes +/- 7 hours. Charging 17 kWh should be 5-6 hours ? Like you calculated |
||
Appreciate
0
|
09-29-2020, 11:59 PM | #33 | |
Lieutenant General
18164
Rep 11,758
Posts
Drives: 2018 M4 Comp Indv
Join Date: Jun 2009
Location: Newport Beach
|
Quote:
i.e., the "battery" is actually a bunch of cells bundled into modules that are bundled into the battery. The battery management software spreads the charge / use / decharge cycles across the various cells to extend the life and effectiveness of the overall battery. Thus in EU cars the software spreads those full-usage cycles serially across all cells equally, but in US cars the software limits the full use down to 17kWh which allows the software to spread the cycles longer on each cell thus increasing the life of the battery overall. In other words, in US vehicles the battery is somewhat burning in parallel instead of in series which provides less burden/load to the overall battery (i.e., the individual cells) resulting in an easier delivered 17kWh since it has 24kwh to play with .... That said, it's important to mention at this point that I have no idea what I'm talking about.
__________________
Last edited by GrussGott; 09-30-2020 at 02:49 AM.. |
|
Appreciate
1
X5 45e1090.50 |
09-30-2020, 12:19 AM | #34 | ||
Colonel
1091
Rep 2,420
Posts |
Quote:
I am not an electric engineer and I al just reasoning like you. It would be interesting to know what the difference in battery management between the US and Europe is. |
||
Appreciate
1
GrussGott18164.00 |
09-30-2020, 12:41 AM | #35 | |
Private First Class
72
Rep 101
Posts |
Quote:
Also 17kWh is the useable capacity. That could mean 0 to 70%, 5 to 5% or 10 to 80%. Depleting to 0% is also not good for Lithium Ion batteries so hopefully BMW has taken that into account. |
|
Appreciate
1
GrussGott18164.00 |
09-30-2020, 01:04 AM | #36 | ||
Colonel
1091
Rep 2,420
Posts |
Quote:
It f I drive my car and I have no electric range left I still have 5% charge in the CD app. And even I know that what we see as 0 or 100 is what they want us to see and not what it effectively is. Like you mention. Tesla advises to charge their batteries to 80% max for daily use and only do to 100% if really needed. Even if planning a longer trip with super chargers it doesn't go to 100% if not needed but this is because the last 20% take longer. |
||
Appreciate
0
|
09-30-2020, 01:10 AM | #37 |
Major General
3159
Rep 6,799
Posts |
The battery management will neither charge the batteries to a real 100% or let you discharge them to 0%. Some of the energy going into the car will be used for heat management, and if really cold out, maybe heating. The ac-dc conversion is only about 95% efficient at 240vac inputs (less efficient with 120vac input). The battery management might start the charge slow if the batteries are cold, and will be slow if they are hot, and will slow as the charge gets near the top. It may not slow down that much as on some other vehicles because of the fairly large 'reserve' BMWUSA keeps. AT some point, and it may not happen each charge, the logic will compare the voltages of each module and might try to balance the cells, and that can take some time, otherwise, it's just dumping power into them in parallel.
You'll always be putting more energy into the vehicle than actually gets stored in the batteries because of the inefficiencies involved. Mostly, that is expressed as heat, and that can require cooling, which uses more energy from the EVSE that doesn't go into the batteries. The energy from the EVSE is limited to 16A, so if your nominal voltage is lower, say in Europe where it might be 220 versus 240 in the USA (mine typically is 247), then that could limit the actual amount of energy. If you're in a commercial location, you might only be getting 208-vac in the USA, and that at 16A is only 3328W, so you won't be maximizing your charge capacity (many commercial charge points use 208, not 240 vac in the USA). The EVSE announces to the vehicle the maximum number of AMPS it can pull, the vehicle will then limit the maximum number of WATTS it will consume based on that announced amperage and the supplied voltage. |
Appreciate
1
moodyhank82587.50 |
09-30-2020, 01:53 AM | #38 | |
Lieutenant General
18164
Rep 11,758
Posts
Drives: 2018 M4 Comp Indv
Join Date: Jun 2009
Location: Newport Beach
|
Quote:
|
|
Appreciate
1
X5 45e1090.50 |
09-30-2020, 02:15 AM | #39 | |
Colonel
1091
Rep 2,420
Posts |
Quote:
But no official netto capacity. Probably they don't want to share what they are doing and just want to confirm 30 miles range. Which is a very safe number. |
|
Appreciate
0
|
09-30-2020, 02:44 AM | #40 | |
Captain
514
Rep 803
Posts |
Quote:
Capacity of each cell is 34 Ah (3.69 V), capacity of each module 68 Ah (29.5 V) and the total capacity 68 Ah (354 V) or 24 kWh. |
|
Appreciate
4
|
09-30-2020, 07:24 AM | #41 | |
Private
98
Rep 50
Posts |
Quote:
Tesla is the same with AC or DC, even using a Supercharger. They recharge to 80% fast, then the Supercharger slows down dramatically. Teslas have the range to hop along the highways between SuperChargers going 80% to 20%, pause to recharge back to 80%, then reach the next Supercharger with over 20%. There is no need to wait during the slow portion of the final 20% recharge. All EVs and PHEVs (like our BMW 45e) have this design to slow down the recharge when nearing full. It is more of a trickle charge near the end so that the battery management system can balance the voltage max in the cells. Last edited by RocketGoBoom; 09-30-2020 at 09:13 AM.. |
|
Appreciate
1
volodp196.50 |
09-30-2020, 09:33 AM | #42 |
Private First Class
44
Rep 165
Posts |
Guys the big question is this. As the battery declines\degrades is there a software/code in place that slowly gives the locked % back to the user? i.e if you lose 1-2kWh from the 17kWh usable, will BMW release the extra 2kWh from the locked pool? This would make the extend the longevity - something that Volt is doing - wondering if someone has any info on that? Because if not this is just poor engineering..
__________________
f25@110K and counting...
Last edited by ketrab; 09-30-2020 at 10:05 AM.. |
Appreciate
0
|
09-30-2020, 10:17 AM | #43 | |
Private
98
Rep 50
Posts |
Quote:
Logically they should do it. However many auto manufacturers don't have the frame of mind of improving the cars after they are sold. The manufacturers build them and sell them. The dealers make all of the money off of long term service. So there is really no incentive for BMW to make any effort to gradually update older plugin cars to release more of the battery reserve. Of course, that would improve the resale value of these cars, but I don't know if BMW thinks like that. Tesla is the first auto manufacturer that has a continuous improvement strategy, with new software updates improving older cars, new games downloading, etc. Over the 4 years that I owned a Model S, every couple of months new features would appear providing more control or scheduling options. Not all older Teslas receive every improvement, some are hardware limited. But even after years, new games and other things would appear in older Teslas. |
|
Appreciate
0
|
09-30-2020, 11:35 AM | #44 | |
Private First Class
44
Rep 165
Posts |
Quote:
ps. Reached out to my bmw rep. Hopefully get some feedback.
__________________
f25@110K and counting...
Last edited by ketrab; 09-30-2020 at 12:03 PM.. |
|
Appreciate
0
|
Post Reply |
Bookmarks |
|
|