Hybrid battery
QMy 2021 Yaris hybrid has two batteries. The main traction battery is a Lithium-ion unit that stores recovered electricity and provides traction power when needed. The much smaller 12volt lead acid accumulator provides power to start the petrol engine and, I believe, is charged from the traction battery.
If the 12-volt battery is allowed to run down (eg. by operating window motors whilst the ignition switch is set to auxiliary) the hybrid system will not initialise because it cannot start the petrol engine. My question is: in such a state, if the traction battery is in a good state of charge, is it feasible to put the ignition switch in the auxiliary or full-on position and wait for the traction battery to charge the 12-volt battery or would I have to wait for a jump-start? Robert Talbot
AThe two batteries on your
Yaris are as you have said the 177.6 volt 4.3 amp/h Lithiumion battery which has 48 cells and the standard 12-volt battery which supplies the vehicle electrics.
The hybrid system on your Yaris has two motor/generators – MG1 and MG2. MG2 is linked to the front wheels and can be used as the power source to drive the vehicle. This is for driving in EV mode. MG1 is deployed to start the engine and to generate power to charge both batteries (hybrid and 12V). The 12-volt battery does not charge from the Lithium battery but from the joint charging system for the two batteries.
So, the 12-volt battery will not charge from the Lithium-ion battery and would need the engine running to charge it.