11-11-2022, 12:28 PM | #309 |
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01-03-2023, 09:43 PM | #310 |
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So I spent some time looking into all of the threads and here are my comments.
A lot of things in the discussions are absolutely true. For example about the battery capacity, how to calculate one full charge, and how the battery reserves are allocated etc. But I feel like there is a lack of discussion of the lifespan of lithium-ion batteries, more specifically, how many total charge cycles can the battery handle before it degrades to an unacceptable level. I found this article here that is very helpful and we should really talk about voltage instead of battery capacity. https://batteryuniversity.com/articl...ased-batteries Let's make some assumptions, say the battery is 100% at 360V and 0% at 240V, and has a total battery capacity of 24 kWh. For 17.1 kWh of capacity, it is about 70% of total scale, let's assume it drains at 5% (246V) and fully charges at 75% (330V). If we run at these modes, even after 5000 cycles that battery has over 90% of total capacity, which is more than the 70% allowable capacity. 5000 cycles multiplied by 35 miles, is roughly 175,000 miles before any observable battery degradation, and you still have a lot of reserves to spare However, if someone enables the 100% (360V) allowable 24 kWh to be used, the capacity of the battery will fall under 85% after just 500 cycles, with 50 miles of range that's just 25,000 miles of driving, assuming even the best case scenario, and it will progressively become worse and lose more range. It is very similar to a cellphone battery, think about how much battery health do you have left after two years and you basically charge it every day right? The 21.6 kWh setting is about 90% of the usable capacity, so roughly speaking it will fall under 90% of total capacity after 1500 cycles, after which the battery degradation will become observable. With 45 miles of range, it's about 70,000 miles. I think that's the main reason BMW is not opening up that capacity in North America due to the 8 yr/ 80k mile battery warranty requirement. Of course, this is assuming the best-case scenario, i.e., the vehicle is parked in a temperature-controlled garage and always charge at a very mild temperature etc. In the real world, these numbers will probably be even less. My conclusion is a. Charge whenever possible, even if you only drive 10 miles each trip. The battery's lifespan becomes "infinite" if it always operated around 50-60%. b. It's not worthwhile to gain 10 more miles of range and risk the warranty and battery lifespan, especially if you intend to keep the vehicle for a relatively long time (I know I do at least). Last edited by Georgetheowl; 01-03-2023 at 09:49 PM.. |
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01-03-2023, 11:33 PM | #311 |
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my U.S.-spec has been in operation since Dec ‘20. been charging via level 2 since month two of ownership. I use most of its battery capacity during my work week M-F and charge every night. I precondition every morning before work while plugged in. I had one HV battery module replaced in Nov ‘21 when my vehicle was flagged for recall while in for a different service.
I did not do the battery mod. I’ve generated two telematics reports showing the energy content (usable capacity) of my HV battery: 17.1kWh in Dec ‘20 16.54kWh in May ‘22 16.2kWh in Dec ‘22 Georgetheowl I logged 7k miles during year 1, and 8K miles during year 2. 9k of the 15k miles I’ve driven are electric miles which is a lot sooner than “175k miles before any observable degradation is seen”. response? |
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01-03-2023, 11:54 PM | #312 | |
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One explanation would be that BMW is proportionally adjusting the allowable capacity based on the battery degradation. 16.2/17.1 is about 95% of the total capacity after 2 years. With 5% per year, it will be 80% after 8 years - so at that time expected usable capacity would be 13.6 kWh. Again this is only my guess. |
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01-03-2023, 11:59 PM | #313 | |
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21.6kWh in May ‘22 20.94kWh in Jan ‘23 |
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01-04-2023, 12:09 AM | #314 | |
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Running Euro spec should cause much faster degradation for the battery. I can't argue with numbers for sure, but the degradation on the US spec is way worse than I expected. Do you mind sharing how to get the telematics data? Maybe I should run one on mine. |
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01-04-2023, 12:19 AM | #315 | |
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https://www.bimmerpost.com/forums/sh...php?p=29686440 for telematics report: on the mobile app, select the BMW Services & Store tab on the bottom of the app, then login through ConnectedDrive Store. select your Vehicle Profile then tap on the drop down menu and select CarData. takes 1-2 days to receive the report (usually 1 day for me) |
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01-05-2023, 06:56 AM | #316 |
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01-05-2023, 07:11 AM | #317 | |
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01-05-2023, 07:19 AM | #318 | |
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still, i doubt it'll read exactly 17.1kWh even when brand new. 16.8kWh is well within operating spec |
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01-05-2023, 08:12 AM | #319 | |
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01-05-2023, 08:22 AM | #320 |
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01-05-2023, 09:39 AM | #321 |
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Engineering problem
I have followed this thread with much interest. It seems to me that the battery active (usable) capacity is the answer to an engineering question. I haven't seen that question really framed very well, so I will give it a shot. There are a number of questions that could be asked:
1) What active capacity would be needed to offer a 10 yr warranty on the battery? This seems to be what BMW has done to meet the dictates of the tyrants in CA. 2) What active capacity is needed to maximize the amount of energy delivered by the battery over its lifetime? Time also degrades as well as cycles so there is an optimum battery management strategy here. This will minimize gasoline usage and maximize electric usage over the battery lifetime. It is still probably not ideal. 3) What active capacity is needed to minimize operating (fuel & electricity) costs over the long run? This would depend on the specific costs for each which differ greatly between Europe and the US. If gas is real expensive and electric charging cheap (and also tax incentives) then it is better to use up the battery sooner to save money on gas and earn the most tax incentives. This is also probably not ideal. 4) What active capacity is needed to ensure that the battery is exhausted right as the economic life of the car is reached? Say I have a 10 yr life battery and an overall economic life for the car of 15 years. The original battery is rebuilt in year 10. When the motor (and other expensive things) goes out in year 15, the second battery still has 5 years of life. Maybe the junkyard can get value out of it, but I almost certainly will get nothing from it. This is a waste. I would rather manage my battery such that it is rebuilt in year 7.5. Then in year 15, everything goes out at the same time. It seems to me that the European battery management delivers closer to this ideal than the US version. I wish BMW gave us the choice. $500 for the coding seems like way too expensive. It would probably take a year or more to recover that cost with the additional fuel savings. Cheers, Kristen |
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01-13-2023, 12:34 PM | #323 |
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01-13-2023, 01:32 PM | #324 |
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Where can you get the coding done for free?
I have been scanning the internet for more information on likely battery lifespan and the cost to replace it. There are 12 battery modules. Right now they are on sale for $1500 each. I'm not sure if there is a core charge or if you get to keep your old ones for possible repurposing as home power backup or off-grid solar. With shipping and installation labor, the total cost will be $20k. Lifespan is claimed to be independent of miles and relates more to age. PHEV batteries fail at about 12 yrs +/-. It doesn't seem to matter if they have 45k mi or 300k mi. Failure is due to an internal short whereas normal aging just reduces capacity while the car is still usable. X5's tend to drop to $15k - 20k after 10 years depending on miles. Therefore, if the battery goes out at that point, the car will be mechanically totaled. It won't be worth fixing and will just be parted out. Our only hope is that the aftermarket can somehow get a hold of Samsung 2 kw battery cells (5 per module) and rebuild the modules. If they can do this for $10k, maybe the car would be worth fixing. It just depends on if PHEV cars can get a reputation for longevity of the ICE (and related parts) that goes well beyond an ICE only car. I suspect that the best strategy is to maximize the early use of the battery and expect to replace it at 7 to 8 year intervals (assuming that the replacement cost can be reduced). The other possible strategy is to drive the heck out of the car such that it has 250k - 300k mi at 10 years and then just dispose of it when the battery goes. Cheers! |
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01-13-2023, 03:11 PM | #325 |
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01-14-2023, 01:47 AM | #326 | |
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Just can confirm. Extend my range. Every day use about 22KWH by city cycle. This is about 65-68km winter -15-20C outside. By the way. Was in roaming country. Where my atm work. Order Telematic report. Look screen. Last edited by Akh000; 01-14-2023 at 02:00 AM.. |
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01-14-2023, 01:52 AM | #327 |
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01-14-2023, 06:00 AM | #328 |
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01-14-2023, 08:18 AM | #329 | |
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but just to clarify, you highlighted the kWh needed to fully charge your battery, which will always be higher than the usable capacity due to charging losses. your usable capacity after the mod is now 20.72kWh found under “Energy content of the high voltage battery” (a few line items lower) |
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01-14-2023, 08:53 AM | #330 | |
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This is with SOC = 100. I don't try lower. |
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