400A vs 500A Cables at High Amps – What’s Working in the Real World?

[Sam007]

We’re starting to see more EVs (fleets and passenger cars) pulling close to 315V@470 amps during DC fast charging. That raises the question: which cable setup really makes sense?

• 400A air-cooled cables → simpler, easier to get, but you’re running closer to the limit.
  
  
• 500A liquid-cooled cables → more headroom and stable temps, but added cost and complexity.
  

Curious what the community has seen in practice:

• Do 400A cables hold up well at that level, or do you see throttling kick in?
  
  
• Any noticeable differences between summer vs winter sessions?
  
  
• For fleets that need quick top-ups, when does it make sense to bite the bullet and go liquid-cooled?
  

Would love to hear real-world experiences — whether you’re running public sites, testing in labs, or just paying attention to how your EV charges.

 

[bwilson4web]

A few days ago, my iPhone in "Time Lapse" video, one frame every 6 seconds, was on a tripod recording the diagnostic display while charging from 13 miles to 180 miles range:

This is first frame showing the V4 SuperCharger at 407 VDC and 0 amps. This was without "preconditioning" the battery after driving nearly 200 miles on a hot day, 100 F. In effect, the battery temperatures were consistent with highway speed driving.

I then recorded the data in this chart:

• "A" - initial peak voltage, 374 V, and current, 463 A
  • There may be a chemistry transition "notch"
• "B" - when the charge reached the peak battery voltage-current
  • The subsequent charge voltage and current were driven only by the battery characteristics
• "C" - the first distinct chemistry "notch"
  • The literature describes how there are internal transient points in voltage-current curve
• "D" - second distinct chemistry "notch"
• "E" - ending chemistry curve

Nickel Cobolt Aluminum (NCA) changes are described in two papers:

• Calendar Aging of NCA Lithium-Ion Batteries Investigated by Differential Voltage Analysis and Coulumb Tracking
• Aging mechanisms of cylindrical NCA/Si-graphite battery with high specific energy under dynamic driving cycles

My $9k replacement, 2019 Model 3 battery pack replaces the original that began failing in the early Spring at ~150,000 miles. A bad valve in a "5-way" coolant bottle probably "cooked" the battery into early failure. Furthermore, Tesla no longer makes NCA 2170 cells used for Model 3 having moved on to LiFeP battery chemistry. This is one of the last NCA battery pack that will ever be. So I want to understand my battery aging mechanism to maximize the life.

These charge curves led me to understand shorter drive segments between SuperChargers is the fastest way to reach my destinations. I now charge enough to reach the closest SuperCharger along my route with a 40 mile reserve:

• 1-10 minutes - maximum charge rate for least amount of time per mile of driving.
  • Typically 1-1.5 hours of driving.
• 11-20 minutes - seeing a fall off in charge rate means a longer percentage of the driving time is spent waiting for a slower battery charge.
  • Usually 1.5 to 2.5 hours of driving.
• 21-30 minutes - even slower charge rate reduces the block-to-block time as a greater percentage is at a slower charge rate.
  • A maximum of ~3 hours driving.

I'm not sure my data helps your quest but since it involved the latest model SuperCharger with voltage and current metrics, I offer it as a data point.

Bob Wilson