Charging When Plugged In

It does not charge the 12v battery when plugged in. Most leaving car unused have learned to leave a maintainer/tender/smart charger attached to prevent damage from completely discharging of the 12v battery.

 

leaving it plugged in depletes the 12v even faster. but for 6 months, you want the maintainer mentioned above, or disconnect the neg cable if you don't mind losing a few presets

 

Be sure to get a battery maintainer, which is a trickle charger that is smart enough to not over charge a full battery. That can be left plugged in.

The car shouldn't be left plugged in for extended periods. Unlike lead-acid, Li-ion batteries prefer being kept under full charge for best life. it never gets fully charged, but the manual advises against leaving it plugged in.

 

leaving it plugged in doesn't keep the hybrid battery topped up, it drains the 12v.

the car should not be left for long periods of time with any wall charge left. toyota recommends driving it until the engine comes on, then storing at that state.

 

correct

 

To charge the 12 V battery ("auxiliary battery"), charge the PHV battery first. Turn the car on with ready displayed and set it to the EV mode. Leave the car on in ready in the EV mode for several hours with the A/C and lights off. This will fully charge the 12 V battery.

If the 12 V battery is dead, get a jump start, and then follow the initialization procedure described in the repair manual, which I posted in the maintenance forum.

Prius Prime initialization procedure after the battery is disconnected | PriusChat

 

Which is fine if you are there to do it on a regular basis, say once a week or so. But a battery maintainer is the best course for the starter battery's life.

 

You don't need special maintenance for the 12 V battery if: (a) you drive the car regularly and (b) you charge the PHV battery regularly and (c) you avoid short HV trips and (d) you drive in the EV mode for at least once a week and (e) you don't sit in the car with the car not in the ready mode but with lights etc. on.

If you obey these five principles, there is no reason for the 12 V battery to discharge. However, many people don't drive in the EV mode but do short HV trips, which could quickly discharge the 12 V battery, not to mention that it could cause carbon deposits and other problems in the internal-combustion engine. I never use the HV mode for short trips but only for long trips, which is the correct way of driving the Prius Prime.

 

In the OP, the car sits, undriven, for an entire season. Or at least long enough that the starter battery had drained to the point that it couldn't start the car. Many people would leave their car sit for long periods even before the pandemic. For those people, a battery maintainer is the best solution to get the best performance out of the 12 volt.

 

well, some people aren't interested in the thread topic when posting

 

In that case, another solution is:

1. Charge the PHV battery to 80%. (It's better than 100% for PHV lithium-ion battery longevity.)
2. Unplug the charger cable so that the 12 V battery doesn't quickly drain.
3. Have the house sitter turn the car on to READY in the EV mode (which is the default mode) for half hour once a week. Note that READY must be displayed.

The only caveat is that if the house sitter forgets the car on, this would be no good, with the ICE eventually kicking in and so on.