PHEV10 and PHEV40 Opportunity charging impacts

What do they mean by frequent charging?

 

Makes sense. The EV40 seems to hold up better.

 

I assume the 'aggressive' cooling cycle is close to the Volt cooling cycle.

 

Not in this comparison. The comparison in the paper is for two blended PHEV, like PiP.

Here are the clues. PHEV10 electric motor power = 40 kW. PHEV40 electric motor power = 43 kW. Volt has 111 kW motor so it will use the battery more aggressively.

PHEV10 ICE power = 77 kW and PHEV40 ICE power = 80 kW. PiP ICE has 73 kW and Volt ICE has 63 kW. Battery power will need to be utilized more due to the weaker ICE power in Volt.

These two model vehicles are very heavy too. PHEV10 weights (3,779 lbs) as much as the Volt. PiP weights just 3,165 lbs.

 

Basically, the finding of this reports said if PiP has a bigger battery with 40 EV miles range, the battery will last 14-15 years instead of 11-12 years.

 

The report seems to highlight that a PHEV in a hot climate and today's battery tech can really benefit by liquid cooling. This leads to a larger battery for optimum.

A PHEV10 with opportunity charging is going to lose capacity, making it less and less useful in hot climates. These also have problems in cold climates. I don't think its surprising that if you use the reports assumption of $300/kwh cost at the pack level a phev10 is too small unless a larger pack can not fit for volume reasons.

 

68 deg F chilled liquid cooling in Phoenix, AZ can extend the life by 3-4 years. However, the worse case is 8.5 years. What about the energy required to chill it? The comparison did not include the added weight of the liquid cooling nor the chilling equipment.

Toyota suggests avoid leaving a full charged battery in the sun (parked). Instead, they suggests you start charging and finish right before you are ready to drive off. Since PiP charges in about 3 hours. Starting the charge at 2pm and ends at 5pm should extend the life of the battery. Don't let the "perfect" be the enemy of "good enough".

Fast charging also reduce the life of the battery and this study does not include it. PHEV40 will need to use L2 fast charger and start around noon (when the heat is at peak) in order to finish by 5pm.

The break even point for me is 336 Wh/mi (@ 22 cents/kWh) vs 50 MPG (@$3.7 per gallon). Since I am averaging 264 Wh/mi driving mostly in the city, electricity costs less to run. It wouldn't make sense to use electricity on the highway/highspeed for me.

BTW, this thread should be in PiP forum.

 

I just want to add that PiP has a chilled air cooling. It is better than the "limited cooling" in the report which is blowing in outside ambient air.

 

Volt does not have 68 deg F chilled liquid cooling. I don't think it even have isothermal (always maintain battery at 82 deg F) cooling. Tesla does isothermal cooling.

 

Just replying in regards to the report you posted. Sheesh!

 

If you look at the report they had 7.8 years as the low case for batteries. The worst case would be infant mortality < 1 year. The authors appear to have tried to take into account the added weight and reduced efficiency of a cooled PHEV40. The PHEV uses 7.5% more energy per hour as per their assumptions chart. You may disagree with their numbers, but they clearly spelled out what they considered and what they did not. Not preconditioning does harm the charging efficiency, and a penalty must also be paid on non-cooled packs in hot weather.

You still are charging at the heat of the day. They are just talking about loss of capacity with a very limited 782 cycles in test. There are not judgments in the report, only facts as the NREL authors see them. Liquid cooled larger packs should retain capacity better in hot climates. Chemistries may in the future deal better with these conditions.

DC fast charging reduces capacity, L2 charging 3.3kw or 6.6kw should not in a chilled pack. It likely will result in less capacity loss. This report has all the optional charging at a 1.5 KW L1 level.