Featured DOT Announces EV Charge Station Corridors Program

cool! i can't wait to find out where the chargers will be. my goal is to drive to florida and back on ev, before my kids take my license away. and to here them tell it, that isn't too far away.

 

With the PiP or a Tesla?

 

I'm not selling the i3-REx for a pure EV. Too many gaps or long detours.

Bob Wilson

 

by the time those chargers are up and running, it will be a 500 mile bev for 20k. and it won't matter if i can't drive, because we'll have self driving cars.

 

I totally agree

 

There is another problem with longer range EVs, the rate of charge. Using my BMW i3-REx 220 W/mi, it looks like:

• 100 miles - 22,000 kWh - 80% in 30 minutes -> 35.2 kW rate, 147A @240VAC
  
• 200 miles - 44,000 kWh - 80% in 30 minutes -> 71.0 kW rate, 294A @240VAC
  
• 500 miles - 110,000 kWh - 80% in 30 minutes -> 176.0 kW rate, 735A @240VAC

These are unreasonable currents. So let's take something easier, less than 100A:

• 100 miles - 147A @240VAC -> 77.5A @480VAC
• 200 miles - 294A @240VAC -> 98A @720VAC
• 500 miles - 735A @240VAC -> 77.5A @2400VAC

Actually it would be DC using an external AC to DC converter. Still, these are impressive power rates ... substation levels.

Bob Wilson

 

It depends.

The rate of fast charge, battery temperature during the charge (and effectiveness of the battery cooling system, if there even is one), and exact battery chemistry all seem to affect this.

Quick charge a Nissan Leaf battery multiple times a day in summer, you will hurt the life.

Supercharge a Tesla Model S battery, you probably won't hurt it at all.

 

State of final charge is another factor. Taking the pack to 80% as oppose to 100% is better for the pack's life.

Being able to actively cool the battery seems to be an important factor in preventing degradation of the battery while fast charging.

 

are we talking real percentages, or perceived from dash readout?

 

.....an explanation that I'm waiting too from the OP............

 

Real. Most plug in cars limit that top charge for pack life but some allow higher. Tesla's default to that safer level, but allow a range charge that goes higher if the driver desires. There are warnings about battery life if regularly done.

 

My wife saw a govt sponsored charge station down near the beach in San Diego, but the charge head was missing - vandalized and or removed .

Kenny

 

unfortunate. you have to stay on top of those things. maybe the locations have to be given more thought.

 

Temperature management is so important for our BMW i3-REx that it has active, liquid cooling and heating system. Knowing what happened to Prius, air-cooled, NiMH batteries, I agree this is the way to go. But it also means part of the power goes to thermal management.

If there is one lesson learned from the Prius is the importance of thermal management. IMHO, future engine/transmission systems should be covered with conformal insulation or fully insulated engine compartment. Heat should only leave as needed to keep the engine and transmission as close to the operating temperature as possible. As we've learned with block heaters, this should also include active, plug-in heating. Cooling is usually not needed since few environments are hot enough to reach 70C with living humans around. Only today's batteries could do with active cooling.

Bob Wilson

 

what happen to prius nimh batteries?

 

Can you be a little more precise?

If you asking about temperature, North Alabama does not get really below 32 F to allow me to experiment. However, we know below 50 F, the Gen-1 performance really falls off. Yet once the engine/transmission warm up to operating temperature, the car performs normally. Just it takes a long time to get there. But here the battery never gets cold enough to investigate that performance area.

We do have high temperatures and I've bought failed modules for testing. What I've learned is:

1. high temperatures > 50 C are easily reached, especially after the car is shutdown
2. high temperatures weaken the terminal "O" ring leading to loss of electrolyte and electrolyzed gas
3. in some cases, this leads to local heating that when on the top of the cell can ignite the explosive, electrolyzed gas and blow off the top of the module
4. temperatures continue to rise AFTER the car is shutdown and the air-cooling in hot climates is inadequate

I like the NiMH chemistry because it does NOT generate a small amount of inert chemicals with each charge-discharge cycle. That is one rumored problem with LiON chemistries that NiMH does not suffer. However, the temperature and pressure issues are not trivial and an active cooling system, more than air-cooled, could resolve the issue.

Liquid, active cooled batteries needs to be the standard. Sure, someone may come up with a better battery chemistry but with what we have now, this is what we have to live with.

Bob Wilson

 

your second sentence.

 

Musk will have Autopilot ironed out not too far away - so then it won't matter
.