Battery capacity warranty

BMW's warranty document defines excessive battery capacity loss as "net battery capacity" less than 70% of the "original nominal value." Does anybody know what these terms actually mean and how BMW determines the "net battery capacity?" What does the word "nominal" mean in this context? I've seen the figure 18.8 kWh on some sites, but does BMW actually have this written down anywhere? Do they use shop computers to determine the net capacity or rely on the i3's built-in diagnostics?

I love my i3 and expected some battery capacity loss. Still, this winter's estimated electric range has been as low as 40 miles. Batt.kapa.max is 15.2. I only started checking it recently.

I haven't looked at the Battery stats in the car today but my Chargepoint charger sent 18.966 kW to the car last night and it was around 5% left when the charging started.

The BMW connected drive web app says today:
var comp_market = 'US';
var comp_vin = 'WBY1Z4C55FV5XXXXX';
var comp_dcOnly = 'true';
var comp_lat = '40.2529';
var comp_lng = '-129.77705';
var comp_soc = '18.33099937438965';
var comp_rangeMap = 'RANGE_POLYGON';
var comp_socMax = '18.32';
var comp_chargingLevelHv = '100';
var comp_vehicleMoving = false;

The effective range has really dropped with the cold weather. Also, preconditioning when the car is unplugged from the charger doesn't help. We park outside so we are seeing the temps below the freezing level.

Some of the energy going into charging the vehicle is lost due to inefficiency of the actual conversion to DCV, some goes into conditioning the battery, which could require either heating or cooling, depending, and maybe both. The amount you put in will ALWAYS be less than that stored in the battery. In addition to that the logic boards are running, which takes at least some power. During that process, it will be topping up the 12vdc battery, too. Depending on the actual battery temperature, your total energy stored can be lower in the winter versus what it can hold in the summer.

Setting a departure time or cabin preconditioning, especially on the REx version, when not connected to the EVSE WILL ALWAYS decrease your available range. It's worse on the REx, since every watt of heat for the cabin comes directly on a one-to-one basis from the battery. The BEV has a heat pump, where it can get nearly up to 4W of heat out of one watt of energy from its heat pump. Now, if it's super cold, the BEV will need to use its backup electrical resistance heating (like the REx's only heating means).

To maximize range, you need to have your i3 connected to the EVSE, and program in a departure time. Then and only then will it warm the battery (conditioning the cabin is optional, but also helps, especially on the REx) to maximize range.

jadnashuanh said:

The amount you put in will ALWAYS be less than that stored in the battery.

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I'm sure you meant to write "The amount you put in will ALWAYS be more than that stored in the battery."

alohart said:

jadnashuanh said:

The amount you put in will ALWAYS be less than that stored in the battery.

Click to expand...

I'm sure you meant to write "The amount you put in will ALWAYS be more than that stored in the battery."

Click to expand...

Yep... guess I need to proofread things better. In nature, there's nothing that is a perfect conversion, there's always something lost whether it's heat, light, or sound, etc. Well, can't think of anything that's a perfect conversion, regardless when it comes to energy, at least in the intended effect.