Out of curiosity.
If the E tense PHEV is running in Hybrid mode most of the time and the ICE is only starting intermittently how does the 12v batteries get charged ?
Very often I see the ICE starting on my car for just a few seconds in Hybrid mode when the electric battery needs a bit of help on hills ect, but it’s not running long enough to put any charge into the 12v batteries .
Is the something else in the background helping charge the 12v batteries.
I did read somewhere that they do get a bit of a charge when the main EV battery is getting charged, but what happens when driving, and the ICE is on/off intermittently ?
For example, I can drive to work and the ICE might kick 2 or 3 times but just for a few seconds each time, this must surely put a drain on the 12v batteries ?
What i understand is, the ICE is started by power from the traction battery, the PHEV does not have a starter motor, but uses the drive motor to start the engine.
The ICE, charges the 12v underbonnet battery and then the auxiliary battery once the underbonnet battery is at a certain level.
I also think, from trial and error, that when the car is plugged in the 12 volt battery gets some as well, now this is the trial & error bit, if one only tops up the traction battery( for example not a full 10+kW), then the 12 volt system does get much at all and the engine cuts in and out as required. So topping up the traction battery is not a good idea.
The two 12volt batteries on power the proprietary 12 volt systems, lights, radio etc, to do away with the 12 volt systems would have been very difficult and expensive at the design stage, so they didn’t.
The tech guy at my dealership did say the main 12v gets a charge the same time the traction battery is being charged.
He also said something about the system being open, so the smaller 12v also gets a charge ?
I was just wondering about the effects on the 12v batteries if the car is starting the ICE intermittently on short journeys, but not long enough to put charge back into the batteries.
None of this matters, because both 12V batteries are charged while driving. It makes no difference which mode is selected. When driving, the voltage in the 12V system is always 14.6V; only the current intensity changes, depending on the state of the 12V batteries.
So, the more the PHEV is driven, the better both batteries are maintained.
It’s not a conventional system, that’s why you don’t hear the starter engage with it starts. Also, remember the system will never let the traction battery go flat, there is always something left to start the engine.
As @Andrew_PL says it does, but it’s much more powerful than a typical alternator, which is why the engine uses so much fuel when charging the traction battery (esave:astonished: )
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