OK, time to take a deep breath and write my first post. Here goes.

I've been trying to clarify in my own mind what I consider to be the minimum range that I need for my Model 3, so that when the times comes I can choose the best battery size. I've been following threads on EPA vs. NEFZ vs. real life, the effects of cold, wind, altitude change, ageing and what safety margin one should leave for each segment of a journey. I've also been following threads on what people think will be the available battery sizes, and the scaling of range against the Model S battery sizes. Lots of unknowns and assumptions, but it's keeping me occupied while I share the impatience obviously felt by everyone else!

The ranges on the US Tesla site are EPA, whereas those on the German site (where I live) are NEFZ

I've also assumed battery sizes of 55kWh, 70kWh and 85kWh. If I look at the scaling factors for the Model S between S60, S60D, S75, S75D, S90D and SP100D, and further assume that I want dual motors, then the D models through the S90D scale approximately linearly against the S60 as baseline. I hope this is what will happen for the Model 3, so the EPA ranges for my hypothetical 70D and 85D are 439kms and 533kms respectively.

Then I've applied the following factors:

EPA to typical: 0.90

Cold weather: 0.95

Wind and altitude: 0.95

Ageing: 0.95

Trip Safety Margin: 0.85

In order to find the effective range. Not all of these will need to be applied for a particular journey, but together I hope they determine the worst case degradation that I should experience. This results in the attached spreadsheet.

Back to my original motivation, which is to determine the minimum distance I think I need to be able to go without stopping for a recharge. Once a week we make a round trip in the evening of just under 300 kms, being about 30mins of "landstraße" and 1:15hr of "autobahn". Since we are generally teaching and the traffic is sometimes heavy, we don't want to rely upon an intermediate recharge on the way there, and afterwards we just want to get home. We can also ensure that the car is 100% charged when we leave home. We make other longer trips during the year, but for them intermediate recharges are fine (especially since I normally stop every 2 hours). So this determines my minimum distance. Looking at the spreadsheet, this means that I really need to go for the 85kWh battery size, although there is quite a bit of additional headroom if my hypothetical battery sizes are incorrect - probably a 75D would be sufficient.

Out of interest, we also want to be able to tow my "toy" (which is what I've chosen as my avatar), which weighs about 360kg and sits on a trailer with a combined weight of less than 750kg. I

Any thoughts?

David

I've been trying to clarify in my own mind what I consider to be the minimum range that I need for my Model 3, so that when the times comes I can choose the best battery size. I've been following threads on EPA vs. NEFZ vs. real life, the effects of cold, wind, altitude change, ageing and what safety margin one should leave for each segment of a journey. I've also been following threads on what people think will be the available battery sizes, and the scaling of range against the Model S battery sizes. Lots of unknowns and assumptions, but it's keeping me occupied while I share the impatience obviously felt by everyone else!

The ranges on the US Tesla site are EPA, whereas those on the German site (where I live) are NEFZ

*apart*from that given for the Model 3 (344 kms being a direct conversion from 215 miles). I've therefore based the following on the EPA estimates converted to kms rather than the numbers on the German site. The EPA/NEFZ ratios for the various models are pretty consistent (0.82-0.85) so I think this is a reasonable starting point.I've also assumed battery sizes of 55kWh, 70kWh and 85kWh. If I look at the scaling factors for the Model S between S60, S60D, S75, S75D, S90D and SP100D, and further assume that I want dual motors, then the D models through the S90D scale approximately linearly against the S60 as baseline. I hope this is what will happen for the Model 3, so the EPA ranges for my hypothetical 70D and 85D are 439kms and 533kms respectively.

Then I've applied the following factors:

EPA to typical: 0.90

Cold weather: 0.95

Wind and altitude: 0.95

Ageing: 0.95

Trip Safety Margin: 0.85

In order to find the effective range. Not all of these will need to be applied for a particular journey, but together I hope they determine the worst case degradation that I should experience. This results in the attached spreadsheet.

Back to my original motivation, which is to determine the minimum distance I think I need to be able to go without stopping for a recharge. Once a week we make a round trip in the evening of just under 300 kms, being about 30mins of "landstraße" and 1:15hr of "autobahn". Since we are generally teaching and the traffic is sometimes heavy, we don't want to rely upon an intermediate recharge on the way there, and afterwards we just want to get home. We can also ensure that the car is 100% charged when we leave home. We make other longer trips during the year, but for them intermediate recharges are fine (especially since I normally stop every 2 hours). So this determines my minimum distance. Looking at the spreadsheet, this means that I really need to go for the 85kWh battery size, although there is quite a bit of additional headroom if my hypothetical battery sizes are incorrect - probably a 75D would be sufficient.

Out of interest, we also want to be able to tow my "toy" (which is what I've chosen as my avatar), which weighs about 360kg and sits on a trailer with a combined weight of less than 750kg. I

*really*hope that the Model 3 will new able to tow this weight. The Model X is too large (and expensive) for us, so I'll really have to rethink the Model 3 if it's towing capacity is too small (mind you, I haven't seen any other EV that can tow). Based on our experience towing this with our existing ICE car, I've assumed a 0.70 degradation factor for these long trips. That's based on driving at typically 125-130 kph on the autobahn when not towing, and at 80-90 kph when towing (the German speed limit for my trailer is 80kph). As you can see from the table, that still gives me a reasonable range when towing, at least greater than my self-imposed 2 hour limit.Any thoughts?

David

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