Public charging and you: caveat emptor!

[mike]

Was talking EA and their charging but for the life of me I don't remember which group on #FB

 

So.. here's some food for thought when dealing with 'public chargers'..

[Keith Richard]

Never plugging in for $0.99 a minute... unless I’m getting 5MW charging speeds.


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[Jay Hanke]

This per minute stuff is crazy. I saw that the Iowa PUC was working on getting the rules changed in Iowa to allow for kw based metering.

[Will Andrews]

Yeah, $0.99/minute needs to deliver at least 4 kWh per minute to be worthwhile (IMO $0.25/kWh is fair at high power).  That's about 250 kW.

[Will Andrews]

They do offer reduced pricing ($0.70/min) for a low monthly rate ($4/mo), could easily make that up with one full charge each month.  Assuming you only charge at high power, say > 160 kW, and stop charging once power drops below this level.

[Will Andrews]

I can kind of understand pushing per-minute metering.  From the perspective of someone like EA:

• Delivering 350 kW is expensive
• Each station can have banks of chargers with different power levels that cater to specific sub-sets of travelers, and have different costs associated with installing them.
  • If you don't need 350 kW because you're stopping to eat, why should you pay more so someone else can?
• Making using 350 kW chargers more expensive incentivizes travelers to shorten their charge sessions, which frees them for others that also need quick charges

[mike]

but that's not how EA is doing things.

 

It's the initial handshake power delivery sets the price across the board.

 

Let's talk Model 3 - let's say I'm at 60% but need to go to 80% - and it handshakes at 250kW maximum - now I pay this huge amount yet I know damn well the car is going to limit things to 60-70kW because of current SoC.

[Jay Hanke]

2 minutes ago, Will Andrews said:

I can kind of understand pushing per-minute metering.  From the perspective of someone like EA:

• Delivering 350 kW is expensive
• Each station can have banks of chargers with different power levels that cater to specific sub-sets of travelers, and have different costs associated with installing them.
  • If you don't need 350 kW because you're stopping to eat, why should you pay more so someone else can?
• Making using 350 kW chargers more expensive incentivizes travelers to shorten their charge sessions, which frees them for others that also need quick charges

 

True, but with the higher rate they will get more $ per minute anyway and a faster stall turnover rate. I think this is one place where Tesla has a pretty solid offering. The shared 150kw in the v2 low-density locations makes sense if you take the average charge rate for 2 big-t machines. It also caps their demand charges at 75 kw per stall. The 350 kw doesn't last long and will dramatically increase the demand charges from the utility.

 

I think there are really two buckets. DC fast charge (50kw+) and Level 2. I also think it's reasonable to have the same per kw pricing for either service. I'd happily pay tesla kw rates at a destination charger if it meant having them all over the place. 

[Will Andrews]

 

9 minutes ago, mike said:

but that's not how EA is doing things.

 

It's the initial handshake power delivery sets the price across the board.

 

Let's talk Model 3 - let's say I'm at 60% but need to go to 80% - and it handshakes at 250kW maximum - now I pay this huge amount yet I know damn well the car is going to limit things to 60-70kW because of current SoC.

Yep, I agree, that's why the only way I'd charge at an EA station under the current pricing regime is if one of the following was true:

• I don't have much choice in the location I'm at
• I'm at a low SoC and will only charge long enough to take advantage of high power rates
• I have the option of a lower power charger and will be stopping for a while anyway

 

2 minutes ago, Jay Hanke said:

 

True, but with the higher rate they will get more $ per minute anyway and a faster stall turnover rate. I think this is one place where Tesla has a pretty solid offering. The shared 150kw in the v2 low-density locations makes sense if you take the average charge rate for 2 big-t machines. It also caps their demand charges at 75 kw per stall. The 350 kw doesn't last long and will dramatically increase the demand charges from the utility.

 

I think there are really two buckets. DC fast charge (50kw+) and Level 2. I also think it's reasonable to have the same per kw pricing for either service. I'd happily pay tesla kw rates at a destination charger if it meant having them all over the place. 

Well, I don't have the experience of working for a power company or operating as a large electric consumer directly, but I'm pretty sure the demand charges for 150-350 kW is quite a bit higher than the demand charges for 50-150 kW.  I'd say there's room for a third bucket, for those who want to charge as fast as possible and are willing to pay for it.

[Dan Holtz]

What I really find interesting about their method is how easy it would be to exploit  In theory you could easily get in between the protocols communications and say I can only take a low rate of power for the first minute or however long they are polling for. Once the price has been established say just kidding give it all to me as fast as you can. I don't think they can really account for it being exploitable easily because you could very well pull up with an ice cold battery and not be able to accept a full charge rate right away anyway.