🔋 The Extended Battery Decision (Poll: Which battery option suits you best?)

[sodamo]

Sharing what A-not-I has to say about something that you haven't or can't independently confirm is never the right choice.

Agree

 

[thommeigh]

I don't think that pencils out.

Most of the thousands of dollars you'll spend on the Extended Battery option will not be recoverable at resale.

Noted! Thanks for that info, that’s helpful. I wasn’t necessarily thinking of it in the context of making back my investment, but more generally that a future buyer could be unwilling to consider a used Slate with the standard battery pack.

 

[metroshot]

I am not of the belief that all EVs need 250/300+ mile range. This is what people are used to from driving an ICE vehicle, and I think that's a big part of why this becomes the benchmark.

150 miles would be just fine for my needs... but I acknowledge that I would be able to setup the charging infrastructure at home, and that we'd have a 2nd car that could be used for longer trips, if I wouldn't want to be bothered with charging. And I know that isn't the case for everyone.

If I did go for the bigger battery, it would probably only be for potential resale benefits - but this will definitely depend on the cost of the larger pack, too.

Agree, as a commuter vehicle, 150 mile range is fine.

I have a base standard range EV w/ 70kW battery I use daily and find that I only need to charge once a week at Tesla Supercharger.

Sometimes for weekend trips, I will charge at home.

Always believed in charging to 100% which is not truly 100% since there's an SOC buffer....

 

[AZFox]

Noted! Thanks for that info, that’s helpful. I wasn’t necessarily thinking of it in the context of making back my investment, but more generally that a future buyer could be unwilling to consider a used Slate with the standard battery pack.

I would've thought that originally because I'm an EV n00b (unless you count a golf cart NEV as an EV).

I went from thinking I'd opt for extended all the way to thinking it's a complete waste of money for my use purpose.

I've learned from EV-experienced people posting here that long-term EV owners are not too worried about it.

Obviously some people actually do need extra range, but that number is far fewer than you'd expect.

 

[thommeigh]

I'm probably not sharing a resource that this group doesn't already know about, but I just found some comfort from playing around with https://abetterrouteplanner.com/. Plugging in some frequent longer drives we take and getting a better sense for the time that would need to be spent charging is making me think that the 150-mile range is an even lesser deal than I was already believing it to be. On this one drive in particular, we normally stop halfway through for about 15-20 minutes to pee, walk the dog, etc., and according to this website, that would be all the charging I'd need for the rest of the trip.

 

[KevinRS]

I'm probably not sharing a resource that this group doesn't already know about, but I just found some comfort from playing around with https://abetterrouteplanner.com/. Plugging in some frequent longer drives we take and getting a better sense for the time that would need to be spent charging is making me think that the 150-mile range is an even lesser deal than I was already believing it to be. On this one drive in particular, we normally stop halfway through for about 15-20 minutes to pee, walk the dog, etc., and according to this website, that would be all the charging I'd need for the rest of the trip.

I found the same, with the ~120 mile trip that is my longest, it calculated by default for some reduction in range, and showed I'd need a 5 minute charge somewhere in the trip. I figure on my couple of times a year doing that trip, I can stop for lunch, and get more charge than that site plans for.

Many people in my area would probably use a trip to Vegas as their benchmark though, and that would require 2 charging stops, which is a bit much for the trip. That's where I figure the reasonable cutoff needs to be. If you make a trip regularly that needs 2 stops to charge, you probably need something with a bigger battery. Luckily I have no desire to make that trip.

 

[bloo]

I would think the battery packs are parallel. The voltage difference between a five and eight pack series configuration would take a large bite out of motor efficiency in the smaller battery.

Assuming each pack is 100 Volts (for ease of calculation), five packs give you 500 Volts versus 800 Volts for eight packs. Three problems arise with this arrangement.

Increased current for the same power.
Let's assume moderate acceleration requiring 50kW (67hp). Power = Volts * Amps. An 800-Volt pack would deliver 62.5 Amps to output 50kW. However, a 500-Volt pack would have to deliver 100 Amps for the same power. Amps generate waaay more heat than Volts do. Every bit of energy converted to heat is energy that could've been spinning a motor, instead.

Fewer Volts means reduced acceleration.
The system uses more power under hard throttle. Power is Volts times Amps. Voltage is whatever the battery pack is. However, Amps are limited by both the motor, motor drive, and battery management.

Fewer Volts also means less efficient high-speed operation.
All PMAC motors are generators. That's how regenerative braking is able to recapture energy from the wheels and recharge the battery with it. Generation also imposes a speed limit on these motors. Once a motor is driven fast enough so the generating voltage is equal to the max voltage available from drive system, it cannot go any faster. There is a trick called "field weakening" that advances drive waveform peaks so they occur before the motor peaks. It allows the motor to spin faster with fewer Volts. Yet field weakening reduces efficiency by introducing even more current into the motor.

I don't think Slate is messing with pack voltage like this, as it would significantly reduce efficiency and performance of the smaller battery.

 

[ElectricShitbox]

It's worse than that, because anything higher than 500v is going to need a voltage booster to charge at current Supercharger sites, which I doubt they're adding. So the big pack won't be over 500v, and the small pack won't be over 312v. I really want them to release the battery specs.

 

[bloo]

It's worse than that, because anything higher than 500v is going to need a voltage booster to charge at current Supercharger sites, which I doubt they're adding. So the big pack won't be over 500v, and the small pack won't be over 312v. I really want them to release the battery specs.

And there's no way they're putting in a 312-Volt pack. That's only 220Vrms for the motor. At the 150kW rating, thats a 682- Amps, not including efficiency losses. The performance and efficiency hit for the smaller battery would be huge.

So yeah...pretty sure the packs are parallel.

 

[ElectricShitbox]

Either the modules are different between the two packs, or the voltages are going to be very different.
10.54kwh modules at full pack voltage with their own BMS would be really cool, especially for stuffing modules into EV conversions. But they've claimed the modules are something off the shelf, so it won't be self contained modules you stack in parallel.

 

[cadblu]

I would've thought that originally because I'm an EV n00b (unless you count a golf cart NEV as an EV).

I went from thinking I'd opt for extended all the way to thinking it's a complete waste of money for my use purpose.

I've learned from EV-experienced people posting here that long-term EV owners are not too worried about it.

Obviously some people actually do need extra range, but that number is far fewer than you'd expect.

I appreciate that you created this poll, and in fact the numbers are quite revealing; the majority of folks here are either leaning towards extended or firmly in the extended range camp. I currently daily drive an EV. Let me start by saying, I would hate to plug in every night. My typical range at 80% is 275 miles, and if I take it up to 95% (say for a road trip) I get about 350 miles of range. I have 21" wheels, but if I had spec'd 19's I would have over 400 miles of range. So maybe I'm spoiled, but my use case for the standard range Slate (if it becomes the DD) I would need to plug in every night. That would take some time getting used to.

If this is your first EV, it will be an easier "adjustment period" in my opinion. My advice: make sure your home charger situation is convenient to make the process as seamless as possible. If you need to move cars around, or reverse park to get close to the charge point, it's just going to make it more complicated.

 

[JImmy]

With the ability to plug in to any 120 volt outlet I am opting for the standard. And yes my daily commute is in the range of under 50 miles round trip and less on most days.