Water pump run in EV mode

I thought the power electronics was cooled by its own water loop. At least is was on the G2.

 

The electric motors are cooled by transaxle fluid, as far as I know. But the power electronics have to stay much cooler than engine coolant which is why they always had their own loop before.

 

Nothing specific about running the ICE every so often just this vague "When the system determines that the gasoline engine needs to be started." in the manual. Coolant circulation?

Re: Prof. Kelley at Weber State tear down video. weberauto on youtube. Thread in this forum about it.

Refers to an electric water pump as part of the new external heat exchanger system for the transaxle. P610 has a closed loop cooling system with an internal ICE driven pump. Connects through an external heat exchanger to the primary cooling system (Same radiator?). Not clear but seems the inverter/converter is part of this external loop in a parallel circuit.

See ~7:00 minute mark 7:45 mark Exchanger removal.15:00 to 18:00 mark Internal "atf" coolant flow 22:00 mark. Oil pump pickup tube and stator pipe 37:45 mark. At ~39:30 refers to external electrical intermittent transaxle oil/cooling pump for the Prime only. Not shown as this is the hatchback transaxle. Internal oil/cooling pump Ice driven (HV mode), not the electrical one 48:30 mark and at 1:15:00 disassembled. Prime EV mode electric oil/cooling pump connects to this pump from outside ie it's externally mounted. Oil pump driveshaft in power split/ planet gear at 1:26:40 mark.

Inverter Cooling Parts.
INVERTER COOLING. For 2017 Toyota Prius Prime Four HYBRID | Toyota Marin
This one shows the Prime only electric pump and the external heat exchanger/pump.
OIL COOLER & TUBE (HV OR FCV). For 2017 Toyota Prius Prime Four HYBRID | Toyota Marin

Looks like the inverter and external transaxle cooling share a pump and are inline.
Hose (G922F) connects the transaxle heat exchanger to the inverter pump (G9040).
Hose (G922C) inverter pump via reserve tank to inverter.
Hose (G922AA) inverter to radiator
Hose (G922H) radiator to exchanger

Radiator and water outlet
RADIATOR & WATER OUTLET. For 2017 Toyota Prius Prime Four HYBRID | Toyota Marin
Water Pump
WATER PUMP. For 2017 Toyota Prius Prime Four HYBRID | Toyota Marin

Looks like one radiator housing with two separate coils. ICE and transaxle/invertor.

Edit: Manual doesn't say engine will autorun after so many miles EV or some length of time. Get these instead
"If the vehicle has not been refueled for a certain amount of time and it is
possible that the quality of the fuel remaining in the tank has changed, “No
new fuel has been added recently. Please refuel” is displayed on the multiinformation
display when the power switch is turned to ON mode. If the
message is displayed, refuel the vehicle immediately."
or "Refuel at least 5.3 gal.(20 L, 4.4 Imp.gal.) of fuel every 12 months"
or "In order to prevent the hybrid battery (traction battery) from becoming
extremely low in charge, charge the hybrid battery (traction battery) from
external power source or start the hybrid system at least once every 2 or 3
months"
or "When the system determines that the gasoline engine needs to be started."

Was looking for the resolver that drives the odometer and or the speedometer this morning. ABS wheel speed sensor(s)? MG2 resolver? How many hub revs per mile for the odom.? OEM tire is 833 revs. BMWilson is going ~820.

 

we've been told by users that there is no ice maintenance routine on the prime.

 

I have no personal experience with the Prime yet, but all the under-the-hood pictures I've seen show two reservoirs with pink liquid in them. One is on the passenger side and is bigger, and a smaller one is by the inverter. That strongly suggests to me that the ICE and the inverter have totally separate cooling systems just as before.