Max current draw when charging at 240v appears to be 15a

The highest draw I have seen from mine is 15.4 amps at 242 volts. That was 3.73 kW. An expectation of 3.6 kW is what I normally see and what I would state to others as a reasonable maximum.

 

Here's that info from my JuiceBox. Notice it is the initial spike. Speed slows down a bit after charging settles.

 

It is, but no plug-in vehicle uses its entire capacity. A buffer is reserved at both ends for longevity. In the case of PHEV, there is a reserve for hybrid driving as well. For EV driving, the SOC ranges from roughly 12% to 84%. That means there is really only about 6.3 kWh that you'd replenish from a "full" recharge.

 

Looks great. Toyota will not let you charge to an actual 100% SOC nor will it let you go down to zero. That would just kill the battery's lifespan.

I don't have the actual numbers memorized and don't have time to look them up now, but indicated 100% is actually about 83% and depleted is in the teens which can go a little lower in HV mode after depletion.

And I see that @john1701a just beat me to it. LOL!

 

That can vary quite a bit because the SOC while in HV with a depleted EV range can vary quite a bit even though there is very little movement on the battery gauge due to its scale.

 

If the charging operation has a fixed power limit, then it will reach maximum current only when the line voltage is at the lower end of its tolerance range, something below 230V.

 

HV level naturally varies. Sometimes it is low. Sometimes regen is so high, you recover a little bit of EV range.

 

Just as the battery SOC varies as you drive a regular Prius, it varies when driving a Prime in hybrid mode. When it gets too low, the car charges it back up.

 

The amount you use for a full charge varies from session to session for various reasons. The 12v battery charging system, the battery heater operating, battery cooler operating, climate-preconditioning operating all use more kWh. This time of year, the traction battery heater is the main cause of variation if you live in colder climate. See my data below, Dec charge (kWh) was 7.22kWh per full charge compared to 6.6-6.8kWh during earlier months.

For L1 EVSE, 6.5-6.8kWh is the average full charge. For L2 EVSE, 6.0-6.3kWh is the average full charge. Either way, the portion used by EV mode is ~5.5 kWh.

Monthly average kWh used for a full charge by L1EVSE

 

I believe it has to do with higher efficiency of thicker gauge cabling but I’m sure one of the much more knowledgeable electricians will offer a more complete answer soon.

 

Higher voltage is more efficient. That's why the big transmission lines run at 22,000 volts and is reduced at distribution points.

 

I am not an engineer, but some people have commented that in addition to the higher efficiency of 240V, L2 EVSE takes a shorter time (almost 1/3 of L1) to finish the full charging, thus shorter times to run the traction battery cooling fans and other components of the battery management system all of which uses kWh to run.

 

This.^^^

A small amount of the difference is thanks to higher voltages incurring less of a voltage drop, less heat generated and wasted for the same amount of power, etc. But a big factor is that at L2 you run the cooling fan on the charger, the charger itself with its inherent losses, and the computers, for less than half the time which cuts that electrical overheard in half.

 

Big transmission lines use high voltage to reduce electrical resistance losses, also known in the industry as I-squared-R losses (current * current * resistance, the formula for wire heating). For a given amount of loss, higher voltage reduces the cost of the wire.

As Jerry already pointed out, while this is a factor in L1 vs L2 efficiency, it probably isn't the largest issue.