[waters73]

I’ve never been told when to charge or what the best method is to charging when it’s low. Do you charge when it’s below5,8, 10% etc? I know the rule about charging to 80% but how low do you go to start the charge…

[trivalent]

Originally Posted by waters73

I’ve never been told when to charge or what the best method is to charging when it’s low. Do you charge when it’s below5,8, 10% etc? I know the rule about charging to 80% but how low do you go to start the charge…

Hello. Broadly, your car's high voltage battery is like your phone's battery: it is healthiest at between 20% and 80% state of charge (SoC).

However, in practice your charging habits will be governed by strategy, which you will define according to your situation. Whether you

• charge at home as standard
• can charge at your workplace
• are in notably cold or hot weather
• drive mostly highway or city
• do or do not have many and good public fast charging options

and more will guide you to define your charging strategy, for daily driving and for outlier scenarios.

For example, probably you would rarely have to or choose to get down to 20% SoC for daily driving, and for the health of the battery would not charge it above 80%. But during the long haul part of a road trip, depending on the route, you might often charge to 100%.

As for the best charging method in low SoC, whereas Level 2 (AC) is better for battery health, your car's software governs charging power (aka "speed") for DC fast charging. That's why there is a "charging curve", as you may have seen. It is the expression of how the car's software will throttle charging power according to such criteria as SoC, battery temperature, and charger capacity.

We bear a certain responsiblity for maintaining the health of our car's battery; but the car is programmed to protect its battery against extremes of 1. temperature, 2. SoC, and 3. charging demands.

[MikeElmendorf]

I'm just topping it off every day, either at home with my ChargePoint or with the very slow chargers at my office.

Only used DC fast once, and that was just to test it out. Will rely on that when I do longer distance trips, but I've really just been around town with the holidays, etc since getting my M60 just before Christmas.

Like my phone, I usually keep it fully charged. If the range was better, I'd probably follow the 80% rule. However, talking to friends who already have EVs, they are charging to 100% without concern. I'm only going to have the car for 3 years.

[RichardInCA]

I haven’t got a routine yet, I’ve got below 20% maybe once, but not regularly. Often I’ll do a longer charge if I dip into the 30% range, but with free charging at my office right now, I tend to take advantage of that. I’ll also sometimes charge to 85% or 90% during the day at the office, so I’m back at 80% or just below when I get home and then if I’m not driving for a day or two, the car’s sitting in that ideal window.

It really depends upon what your charging options are. If you’re looking to rely on Electrify America, I wouldn’t wait until you’re too low as getting time on public charging isn’t guaranteed in the same way as knowing you can plug in at home.

[waters73]

Thanks. I’m charging at home with short drives into town for work. The reason I went electric. Maybe I’ll plug in every night that way I have a full tank everyday…

[trivalent]

Originally Posted by waters73

Thanks. I’m charging at home with short drives into town for work. The reason I went electric. Maybe I’ll plug in every night that way I have a full tank everyday…

That is an ideal use case and a classic motivation. But you should decide what "a full tank" will mean based on whether you foresee keeping your car.

[SkykingUSA]

I understand the general recommendations out there about keeping your battery SoC between 20% and 80% for day-to-day usage and only charging to 100% SoC for when you really need it (like on longer trips). However, has anyone seen BMW's official recommendation for charging the car? I would think BMW would have a best practice or recommendation for this.

[cpt]

Originally Posted by waters73

I’ve never been told when to charge or what the best method is to charging when it’s low. Do you charge when it’s below5,8, 10% etc? I know the rule about charging to 80% but how low do you go to start the charge…

According to BMW (owner's manual):
- Preferably charge at AC charging stations for daily use.
- Keep the charge level between 10 % to 80 % if possible, for instance by setting a charging target of 80 %.
- Recharge the high-voltage battery as close to a planned departure as possible. A time frame can be set for charging

The following is also interesting which people don't often realize:
Long stationary periods -> "If possible, park the vehicle with a charge
level between 30 % and 50 %."

Personally, I charge overnight whenever I'm below 30%, since I use up ~20% of charge on a typical day.


(Edit)
Manual download:
https://g60.bimmerpost.com/forums/at...6&d=1695165962
Charging recommendations are on page 324

[trivalent]

Originally Posted by cpt

The following is also interesting which people don't often realize:
Long stationary periods -> "If possible, park the vehicle with a charge
level between 30 % and 50 %."

That is my compromise for now:

Because I cannot charge at home, and given the paltry public charging options available to me nearby, my standard practice is to leave my car charged to 80% for arrival at home (whereupon I expect not to drive it for a few days).

Better a marginal tax on the battery than the risk of me being greatly delayed or stuck en route on an average day.

I look forward to improving my situation within the year.

[RichardInCA]

This video has been stuck in my head for a while….if you go to the 15:55 mark then there’s a brief section on charging where the narrator emphasizes charging to 100% claiming that 100% charge is not 100% of the battery (I know we have ~81.2kWh usable from 84kWh but that’s not a large buffer).

On his channel it claims that Chris is “Head of Genius Operations & Training located at a US BMW Center” which sounds as though he should know what he’s talking about, but clearly this is not a BMW endorsed channel. Any thoughts? Aside from that question, it’s an excellent video overview.

[trivalent]

Originally Posted by RichardInCA

...the narrator emphasizes charging to 100% claiming that 100% charge is not 100% of the battery (I know we have ~81.2kWh usable from 84kWh but that’s not a large buffer).

Right: 100% indicated is not 100% capacity in fact; just as near or at 0% indicated is not actually 0% (since there is a reserve).

Those facts are good to know for atypical scenarios. I have seen Teslas charging to above 100%. And nearly all modern EVs have usable reserve below the indicated 0%.

But for daily use, 10 or 20% to 80% is still recommended given those low and high SoC reserves. That's what I assume, at least.

[Scrapula]

My SA who is extremely knowledgeable about EVs told us to charge to 100% at home the first few times. It’s the DC charging you worry about. Since I share a charger with 2 vehicles, it doesn’t charge every night. I drive a few days then hook it up. It’s sitting at 100% now.

[Windshieldfarmer]

Originally Posted by Scrapula

My SA who is extremely knowledgeable about EVs told us to charge to 100% at home the first few times. It’s the DC charging you worry about. Since I share a charger with 2 vehicles, it doesn’t charge every night. I drive a few days then hook it up. It’s sitting at 100% now.

100% is ok for a bit while preparing for a drive but if it were mine I would never leave it parked for a few days at 100%. There is a host of data stating such. The BMW manual is also very clear about where to keep charging levels. I suspect your trusted SA is not a battery engineer…

[Scrapula]

It’s probably because BMW requires the dealers to charge the cars to 100%. It’s delivered at 100% Cars in for service are charged to 100%.

[SkykingUSA]

Originally Posted by cpt

According to BMW (owner's manual):
- Preferably charge at AC charging stations for daily use.
- Keep the charge level between 10 % to 80 % if possible, for instance by setting a charging target of 80 %.
- Recharge the high-voltage battery as close to a planned departure as possible. A time frame can be set for charging

The following is also interesting which people don't often realize:
Long stationary periods -> "If possible, park the vehicle with a charge
level between 30 % and 50 %."

Personally, I charge overnight whenever I'm below 30%, since I use up ~20% of charge on a typical day.


(Edit)
Manual download:
https://g60.bimmerpost.com/forums/at...6&d=1695165962
Charging recommendations are on page 324

Thanks! That's exactly what I was looking for.

[SkykingUSA]

Originally Posted by RichardInCA

This video has been stuck in my head for a while….if you go to the 15:55 mark then there’s a brief section on charging where the narrator emphasizes charging to 100% claiming that 100% charge is not 100% of the battery (I know we have ~81.2kWh usable from 84kWh but that’s not a large buffer).

On his channel it claims that Chris is “Head of Genius Operations & Training located at a US BMW Center” which sounds as though he should know what he’s talking about, but clearly this is not a BMW endorsed channel. Any thoughts? Aside from that question, it’s an excellent video overview.

I saw that and wondered the same thing. However, after watching so many videos and reading different articles, he is the only person I saw that recommends charging to 100%. So, I am inclined to follow the users manual recommendations.

I think Scrapula's got it right. Charge at home to 100% the first 2 or 3 times, then stick to 80% as the max until you really need 100% again. Maybe do the first 100% top up just before you leave for a trip where you think you can get back home at 80% or lower. That way, the car is not sitting around at home over 80% for very long.

[Scrapula]

My SA said that with a new battery, charge it to 100% at home a couple of times to make sure that it can charge to 100% without issues. Makes sense to me.

[trivalent]

Originally Posted by Scrapula

It’s probably because BMW requires the dealers to charge the cars to 100%. It’s delivered at 100%

That is true of delivery, that I have seen. It is required for calibration, is what I was told.

Originally Posted by Scrapula

Cars in for service are charged to 100%.

But this has not been the case for me. Rather, my car in for service was charged to the charging target that I set (which always was less than 100%).