[jad03060]

Heat is a big issue with any battery. Charging them creates heat. Charging them faster creates more heat, which causes the system to slow down the charge, so partly for efficiency and longevity, stopping before full can have some issues, but it's nothing like when doing a high voltage DC charge, (CCS or in a Tesla at one of their Superchargers)...there, it really makes sense to limit the maximum charge level for time and battery health. As you generate more heat, your cooling must increase, which means more power is going into those systems versus into the batteries. The 45e's onboard charging is half the value of the 50e, so that puts a bound on the heat load. From an overall efficiency, rather than, I think, longevity, BMW chose to offer the optional limit of the maximum charge level. Since the 50e can't do CCS charging, the bigger benefit is more likely limiting the time on a public EVSE where they often impose a time limit, or add costs for sitting there, regardless of whether you're charging or not. IMHO, unless a public EVSE is free, it doesn't make much sense to charge a 45e there, but the level the 50e can accept power starts to make that a bit more of a viable option.

[RetSurfer]

Since I can limit the charge amps and I charge overnight, does it make any sense to lower the intake a little?

[nZtiZia]

Originally Posted by RetSurfer

Since I can limit the charge amps and I charge overnight, does it make any sense to lower the intake a little?

whether you charge at 16A vs 32A or 6h vs 3h, you’ll still use ~22kWh to fully charge from 0-100%.

do you have lower off-peak charging rates? if so, you would want to charge during that period, and because it’s likely a smaller window of time compared to peak rates, you’ll want to charge at a faster rate to complete the charge within that period

if the above rates scenario doesn’t apply, and you’re wanting to charge slower to decrease the heat stress on the circuit wiring, I don’t see why not

[CJ2018]

Originally Posted by nZtiZia

the following post shows where to set the charge level
https://www.bimmerpost.com/forums/sh...php?p=30091772

the 50e BATTERY HOLD simply holds whatever the charge level is at the time the hold is activated. at least that’s what I understand from other posts

agree with your statement. Battery hold is simply an optio to “hold” or stop the battery charge percentage from dropping below the level at the time of press. It does NOT charge it up.

[RetSurfer]

Originally Posted by nZtiZia

whether you charge at 16A vs 32A or 6h vs 3h, you’ll still use ~22kWh to fully charge from 0-100%.

do you have lower off-peak charging rates? if so, you would want to charge during that period, and because it’s likely a smaller window of time compared to peak rates, you’ll want to charge at a faster rate to complete the charge within that period

if the above rates scenario doesn’t apply, and you’re wanting to charge slower to decrease the heat stress on the circuit wiring, I don’t see why not

Nope, Duke Energy here in NC. $.118 all day

[jad03060]

While level 1 charging is less efficient than level 2, limiting the amps MIGHT mean less cooling use, which could save some money. But, a lower heat load over a longer time, might end up a wash. Because of cooling, the actual life probably won't be a significant factor, but that's a bit hard to quantify without a long trial. The batteries need the same DC input voltage, but it isn't as efficient bumping it from 120vac as it is from 240vac up to the nearly 400vdc needed to charge them. So, heat management is both for the batteries as well as the other, high current devices in the circuit.

So, you could try it both ways, and see what the app says about the amount of power used and let us know. Getting the starting points the same is the tricky part, as well as how hot things got during the actual trip. I've had the cooling circuits run at full tilt when trying to recharge after a long highway trip which would skew the results. IOW, it might be tough to accurately evaluate this, especially without lots of samples to average the results.

[SwissBeemer]

Originally Posted by mopaman

I would stand by my statement that you would need to charge to get the full benefit of e assist. Most of the time it is available, but under a very high load, or starting out on a very cold day with an “empty” battery it is limited.

This was mentioned in the thread as well and besides being a quite unlikely scenario would also apply to a full battery, as mentioned by jad.

As to the high load there's a video linked in the thread that shows someone doing a 0-150mph (I think) pull with an empty battery and the difference up to 124mph between an empty and a full battery was 0.4s if memory serves me right.

[aquanox]

When dash shows --- miles left, if you read BMS data, it will still report 35% charged, and the average cell voltage is 3.617v. Hard acceleration will kick on the engine, but assume you don't mind going too fast, and assume it still pulls 250 amps, it should generat ~82.5kw, about 20kw less than full pack.

I guess BMW use exclusive bottom reserve cos they want to preserve the oomph when the pack is empty, especailly for those who buy the car due to the tax discount and use it as a 40i. Battery wear will gradually level and most peoople don't keep their car long enough to need that warranty anyway. Better have ther performance now than worry about longivity.

[aquanox]

My 2c on longenvity, I believe it is best to schedule the charge so the car finishes charge right before the morning communite, especially in the summer months, so the battery doesn't get charged immediately when it is piping hot, also it spends less time at high voltage.

Charge current shouldn't be any issue as 45e charges sloooooow, 50e at 7.4kw is still 0.25C.

During charging, idealy you want to keep the room temperature cool and avoid having a full pack sitting in hot garauge overnight, ask me how I get 11% capacity loss in 1 year. If you hear fan kicking on, the battery or the charge controller is overheating, this usually only happens if you charge the car right away after long dirve.

Also when the car is not used for couple days, don't plug in. The pack still have plenty energy in reserve and it won't damage the battery. If you plug in, the pack will set at 4.2V/cell, not ideal especially in summer.

[nZtiZia]

Originally Posted by SwissBeemer

This was mentioned in the thread as well and besides being a quite unlikely scenario would also apply to a full battery, as mentioned by jad.

As to the high load there's a video linked in the thread that shows someone doing a 0-150mph (I think) pull with an empty battery and the difference up to 124mph between an empty and a full battery was 0.4s if memory serves me right.

as mentioned in the other thread, the 45e's battery during those tests wasn't empty. it was very low, but not empty. the video maker notated it as "almost empty." there is enough difference to make this distinction given many people out there want to know how the 45e's engine performs during high demand with an "empty" battery. 3+ years since release, no videos of this exact scenario exist.

i did just come across a video linked in the following thread https://g05.bimmerpost.com/forums/sh....php?t=2014283 that shows a MY24 50e accelerating 0-60mph with a battery at 0%. the video wasn't very clear, and while the instrument cluster layout is different than the 45e, the lower right of the cluster did show what appears to look like - - - miles. the vehicle accelerated pretty aggressively, achieving close to 7k rpm. mind you, the 50e's engine has a higher bhp and possibly different programming/engineering than the 45e's. eBoost may not even be a feature on the 50e, and i couldn't see "eBoost" on its rpm gauge (hopefully a 50e owner can clarify), so one can't assume the 45e will behave similarly under these conditions.

[tdlutz24]

Originally Posted by nZtiZia

as mentioned in the other thread, the 45e's battery during those tests wasn't empty. it was very low, but not empty. the video maker notated it as "almost empty." there is enough difference to make this distinction given many people out there want to know how the 45e's engine performs during high demand with an "empty" battery. 3+ years since release, no videos of this exact scenario exist.

i did just come across a video linked in the following thread https://g05.bimmerpost.com/forums/sh....php?t=2014283 that shows a MY24 50e accelerating 0-60mph with a battery at 0%. the video wasn't very clear, and while the instrument cluster layout is different than the 45e, the lower right of the instrument did show what appears to look like - - - miles. the vehicle accelerated pretty aggressively, achieving close to 7k rpm. mind you, the 50e's engine has a higher bhp and possibly different programming/engineering than the 45e's. eBoost may not even be a feature on the 50e, and i couldn't see "eBoost" on its rpm gauge (hopefully a 50e owner can clarify), so one can't assume the 45e will behave similarly under these conditions.

Take notice to the torque readings as they accelerate. (right side of the steering wheel) I don't believe the battery was completely out of the picture. Nice video though.

[eelnoraa]

Originally Posted by nZtiZia

as mentioned in the other thread, the 45e's battery during those tests wasn't empty. it was very low, but not empty. the video maker notated it as "almost empty." there is enough difference to make this distinction given many people out there want to know how the 45e's engine performs during high demand with an "empty" battery. 3+ years since release, no videos of this exact scenario exist.

i did just come across a video linked in the following thread https://g05.bimmerpost.com/forums/sh....php?t=2014283 that shows a MY24 50e accelerating 0-60mph with a battery at 0%. the video wasn't very clear, and while the instrument cluster layout is different than the 45e, the lower right of the instrument did show what appears to look like - - - miles. the vehicle accelerated pretty aggressively, achieving close to 7k rpm. mind you, the 50e's engine has a higher bhp and possibly different programming/engineering than the 45e's. eBoost may not even be a feature on the 50e, and i couldn't see "eBoost" on its rpm gauge (hopefully a 50e owner can clarify), so one can't assume the 45e will behave similarly under these conditions.

I found it very difficult to get 45e HVB to really empty. yesterday we picked up 45e from dealer for instrument cluster replacement. HVB is supposed to be empty for this procedure. The gauge did show "---", and apps show 0%. yet, when we left dealership, I still manage get 1.8miles in EV mode before ICE turn on. This kind of says, even with BMW diagnostic charge charge setting, it really isn't that empty. And I further think as long as you drive the car, the actual HVB level is probably fluctuating between "empty" and 1-2%, just due to regen, ICE charging ....

If I have to create a scenario for 0-60 with empty battery, I think have to do this.
- Run the car down until ICE turn on.
- Drive to the start point of the drag race, or wherever you want to do 0-60.
- Wait there with car on either hybrid or electric mode, use car's electronics, AC, mucis .... draw from 12V. Then ICE will turn on after sometime because HVB can no longer charge 12V. I think this is empty
- Switch to sport mode, and launch for 0-60 or 1/4 .

[aquanox]

If you read the Json file contained in the data folder from the CarData Report, it will give you car's complete charging history, the time used in this file is UNIX time. Assume you use all your battery once in a while. Once you grabe time and energyIncreaseHvbKwh and then exclude outlier, you use the result to calculate the battery degradation at any point of time and make a degradation curve.

DO NOTICE THIS FILE ALSO CONTAINS LOCATION INFO for each charging session, be careful what you might find.

[aquanox]

Originally Posted by eelnoraa

I found it very difficult to get 45e HVB to really empty. yesterday we picked up 45e from dealer for instrument cluster replacement. HVB is supposed to be empty for this procedure. The gauge did show "—-", and apps show 0%. yet, when we left dealership, I still manage get 1.8miles in EV mode before ICE turn on. This kind of says, even with BMW diagnostic charge charge setting, it really isn't that empty. And I further think as long as you drive the car, the actual HVB level is probably fluctuating between "empty" and 1-2%, just due to regen, ICE charging ....

If I have to create a scenario for 0-60 with empty battery, I think have to do this.
- Run the car down until ICE turn on.
- Drive to the start point of the drag race, or wherever you want to do 0-60.
- Wait there with car on either hybrid or electric mode, use car's electronics, AC, mucis .... draw from 12V. Then ICE will turn on after sometime because HVB can no longer charge 12V. I think this is empty
- Switch to sport mode, and launch for 0-60 or 1/4 .

The battery is never empty due to the 30% bottom buffer, and when dash shows 1 miles left, it can still pull 330v, 261a, that's still 85.8kw, still matchs the 83kw on the spec sheet. Discharge any lower than that the ice will kick in. Unless someone can try it on Autobahn with data logging, it will be hard to find the actual cut off.

[eelnoraa]

Originally Posted by aquanox

The battery is never empty due to the 30% bottom buffer, and when dash shows 1 miles left, it can still pull 330v, 261a, that's still 85.8kw, still matchs the 83kw on the spec sheet. Discharge any lower than that the ice will kick in. Unless someone can try it on Autobahn with data logging, it will be hard to find the actual cut off.

Yes, that part I get. For all the "empty" I mentioned, it is refer to the car can no long use HVB.

[jad03060]

As I understand it, the HVB is always in the picture. To get 12vdc to operate most of the normal vehicle electronics and the HVAC systems, it needs the DC-DC converter that is powered by the HV system, and while the power might basically be passing through, the EV motor as an alternator would then be in the picture unless the logic required the EV motor to be propelling the vehicle. Roads aren't billiard ball table flat for the most part, either, so there's the opportunity to produce a little regen which can build a little bit of power back into the battery system. The computer is always trying to balance the available power sources. Where you might lose some EV power is on a long uphill mountain grade, but would regain some as soon as it turned downhill again.

[maka007]

Originally Posted by aquanox

My 45e is about 1 year old and charged daily. Current Energy content of the high-voltage battery is 15.2kWh, so about 11% degradation.

Also, when fully charged, the 45e pack voltage is 399.5v, average cell voltage 4.16V. Meaning the 30% reserved is all at bottom, which I believe is not ideal for longevity.

I live in texas btw, hot summer.

I went this route too and captured many CarData reports as I was worried that my 45e battery is degrading.

When I took it to the dealer for one year service, they ran a battery test and I got a print out that my batter is at 95%. The car data report shows otherwise, and numbers similar to yours, see below.

I wouldn't worry about it and just drive and enjoy!

[aquanox]

Originally Posted by maka007

When I took it to the dealer for one year service, they ran a battery test and I got a print out that my batter is at 95%. The car data report shows otherwise, and numbers similar to yours, see below.

The 95 is most likely the battery BMS reading, my pack also reads 95%, since the battery never get fully cycled, BMS cannot calibrate the pack and presumably will just give an educated guess of the overall health.

[aquanox]

Finally got time to finish the chart

Originally Posted by aquanox

If you read the Json file contained in the data folder from the CarData Report, it will give you car's complete charging history, the time used in this file is UNIX time. Assume you use all your battery once in a while. Once you grabe time and energyIncreaseHvbKwh and then exclude outlier, you use the result to calculate the battery degradation at any point of time and make a degradation curve.

DO NOTICE THIS FILE ALSO CONTAINS LOCATION INFO for each charging session, be careful what you might find.

[eelnoraa]

Originally Posted by aquanox

Finally got time to finish the chart

Nicely done. It looks like degradation is very linear. I was expecting it will have an initial drop, then settle down to a very shallow, almost flat capability, then drop off steeply at end of life.

[aquanox]

Originally Posted by eelnoraa

Nicely done. It looks like degradation is very linear. I was expecting it will have an initial drop, then settle down to a very shallow, almost flat capability, then drop off steeply at end of life.

I though the same, hopefully the degradation will slow down.

As of now, the battery has a cumulative charge of 5137.22kWh, equivalent to 213.16 cycle.

Judging by the cycle count, if this is an iPhone battery, I would say its doing pretty well. Sadly it is bolted on a car. With the current usage pattern, I might have a chance to use the warranty.

[maka007]

Originally Posted by aquanox

I though the same, hopefully the degradation will slow down.

As of now, the battery has a cumulative charge of 5137.22kWh, equivalent to 213.16 cycle.

Judging by the cycle count, if this is an iPhone battery, I would say its doing pretty well. Sadly it is bolted on a car. With the current usage pattern, I might have a chance to use the warranty.

Great chart, but it won't stand with BMW in my experience. The warranty on the PHEV battery is only for failures, when there is an error upon diagnostics. I couldn't find anything written down that in X number of years it will degrade by Y percent, etc. Even with getting lower miles on EV, is it "wear and tear"? Batteries don't last forever.

When I shared several Car Dara reports showing it's down ~10%, even a foreman didn't take it into account. They ran a battery test and that was it. So I'll keep collecting the data in the meantime.

If someone knows otherwise, would be curious to find that out.