When running in hybrid / full electric mode where do things like heaters, wipers, media, and all other features get their power supply from ?
Is the supply shared between the traction battery and the 12v batteries ?
Or is it shared between the two 12v batteries and the traction is purely there to drive the wheels ?
I’ve noticed the traction battery runs out quicker if the heaters or A/C are on in hybrid/electric mode.
Even though the predicated mileage is now showing 24 miles after a full charge (it was showing 32 -35 in the warmer months), the actual % charge of 100% after a full charge seems to drop a lot quicker than the predicated mileage.
In other words I’m not getting the 24 miles predicated out of a 100% charge if heaters ect are on.
I’ve also noticed the ICE start up on occasion when turning on the heaters, depending on what the heating level is set to.
Everything that runs on 12V draws power from the 12V batteries. The traction battery compensates for the energy deficit in the 12V batteries when running on electric power, acting like an alternator in an ICE. The more current you draw, the shorter the distance you’ll travel. Unfortunately, your car doesn’t anticipate that you’ll draw that much current, so it shows you a median.
The voltage of 14.7V in the 12V system when the “Ready” light is on (and the ICE is not working) does not come from nowhere.
A 12-volt battery cannot exceed 12.8V when idle. 14.7V is the voltage when an external source (alternator, rectifier, traction battery) is connected/working. If this source is disconnected, the voltage will drop to 12.8V over time.
I believe an alternator on the ICE will only charge a battery to around 80-90% (https://www.ctek.com/uk/news/why-your-alternator-is-not-enou gh-for-charging-your-12v-car-battery), this is to prevent overcharging and the hazards that come with it. So I would assume that any charge that comes from the traction battery, which I’m not convinced any does, (yes BEV’s do, but not sure about PSA PHEV’s) would also not overcharge the batteries.
My understanding is the traction battery is just that, and when plugged in both the traction battery and the auxiliary battery get charged, however, the 12v battery is only charged by the engine. BUT, once the 12v battery has been charged by the alternator extra charge from it goes through a converter and then charges the auxiliary battery.
Since early December last year, I have started to plug mine into a battery minder overnight every few weeks, and the amount of random, i have experienced very few 5 min engine runs or startups since, and been able to run in EV mode alot.
If anyone has a link to an official document that explains exactly how the system works would be very handy.
@ Stu.
Do you charge the main 12v or the smaller 12v every few weeks or both ?
And do you disconnect either or both from the car to carry out the charging ?
When you say the ICE charges the 12v battery and once charged a converter charges the “auxiliary battery” do you mean the smaller 12v battery.
I’ve had issues with both the 12v batteries on my Phev DS4, they’ve been changed 4 times in just over 12 months.
I’ve also had mixed info from the tech people at my dealership when asked how the system works in regards to charging the 12v batteries.
The info I’ve had is pretty much how you’ve explained it, so when the traction battery is being EXTERNALLY charged the main 12v is also charged, and I THINK they also said some current runs through to the smaller 12v, but I cant be 100% sure of that ?
And then I’ve been told by another technician at the same dealership, the external charging of the traction battery does not charge the 12v batteries at all, this is all done by the ICE when its running, two totally separate systems !
I’m seeing my ICE kick in frequently lately, it runs at 1400rpm and then drops back and ticks over at 800rpm, for a little while, but whilst this is happening it still using the traction battery to drive the car, you can see this by bringing up the power distribution display on the dash whilst driving.
It does this when theres some charge left in the traction battery, so I’m assuming its because I havent used the car much and not enough mileage with the ICE running to charge the 12v batteries ?
So to me it makes sense if the car has done little mileage or not been used much, and therefor the 12 v batteries require charging from somewhere the obvious solution is for the car to kick in the ICE to supply this charge, rather than drain the traction battery for this ?
When the traction battery charger is connected, do not simultaneously charge the large 12V battery. This battery is charged continuously when the PHEV is connected to a 230V socket. Only the auxiliary 12V (small) battery can be charged. To determine this, simply connect the traction battery charger, open the hood and glove compartment, and measure the voltage on both 12V batteries immediately after ignition off and after 10 minutes off do nothing. The large battery will remain at 14.5V, while the small battery will initially reach 14.5V, and after 10 minutes 12.5-13.0V.
Conclusion: the small battery can be charged because it is off-grid while charging the traction battery, but the large battery cannot because it is then charged from the power source that is charging the traction battery.
The large 12V battery can only be charged if the traction battery charger is not connected. You should not charge a large 12V battery with two power sources at the same time, because both sources will have incorrect information and will not do their job properly.
Traction battery & large 12v battery BOTH get charged at the same time when the traction battery is being charge from wall charger or home socket.
Small 12v battery does not get charged at the same time.
Its ok to charge the small 12v with a trickle charger at the same time the traction battery & 12 large are being charged from external source, ie: wall charger or home socket.
ICE starts up if large 12v OR small 12v battery require extra charge due to low mileage /lack of use ?
Ok to leave both 12v batteries connected to the car if manually trickle charging but , WAIT AT LEAST 10 mins after switching ignition off before connecting & switching on the trickle charger.
no, because there is still 14.7V - even when the ICE is not working
yep
Summary:
A small 12V battery can be charged at any time. It’s best to turn on the charger when the controllers are in sleep mode, i.e., no sooner than 10 minutes after the car is locked.
A large battery, only when the traction battery is not being charged. The conditions are the same as for the small battery, i.e., 10 minutes after the car is locked.
Why minimum 10 minutes? Because after this time, the voltage drops and the batteries are approximately 12.8V or lower, and the voltage doesn’t trick the intelligent charging of microprocessor-based chargers like the CTEK MXS 5.0 or 7.0.
@Andrew_PL, Interesting I will check voltages next time I plug in both wall charger and battery minder. But I think I’m doing it right as both are not started at the same time. The minder is connected when I first park the car, then I plug in the type 2 plug, but ALWAYS use deferred charge, which starts at least 6 hours later, so it’s possible the battery minder has done its job already.
Note to anyone that may be using a battery monitor (trickle charger), do not connect directly to the earth(-ve) terminal of the battery, use the nearby earthing post, as it could damage the battery controller.
Wheres the earthing point for the smaller 12v battery, is there one inside close to the battery ?
Any suggestions why the ICE starts up even if theres charge in traction battery and outside temps are normal ?
I’m sure theres a quote in the manual saying something along the lines of having to drive the car for around 50 miles to put charge into the 12v battery if the car hasnt been used or only does low mileage.
Is the point when the ICE will kick to maintain charge in the 12v battery if the traction battery drops below a certain percentage ?
By this do you mean whilst driving it getting charge from traction battery ?
Yes, because something has to keep the 12V batteries in good condition.
Whenever the READY light is on, the voltage is above 14V and both batteries are being charged. This isn’t possible without a power source. This source is the traction battery or the ICE. Details aren’t provided, but that’s what logic dictates given the voltage is so high.
I’m just a little confused why the ICE on my car kicks in , runs at 1400rpm then drops to 800rpm, whilst the traction battery is driving the wheels in hybrid mode ?
I don’t think there’s an earth terminal on the auxiliary battery (armrest) only ever seen this battery from inside the armrest.
The earthing terminal I was referring to its next to the 12volt under bonnet battery.
I understand that the, ice will start and idle for a number of reasons, such as, low 12v battery charge, to stop the fuel waxing in the system, and…
This is where my opinion is my opinion, and until proven otherwise, by official documentation will remain my thoughts on how the system works as searching the web gives conflicting information.
When you plug you car in, it charges the traction battery and possibly the auxiliary battery. (More likely), but I don’t think the underbonet battery. When you have been using the 12volt systems alot, Lights, Wipers, heater fans, radio etc (all those systems found in a standard car), the ICE will start and charge the 12volt (under bonnet) battery to 80%(ish), once that level has been reached, it will top up the auxiliary battery. However, if instructed by the driver it will also charge the traction battery.
I’m not sure but I think these cars do not have a traditional alternator, but the car actually takes a feed from the main electric motor. Which could be why, the ICE starts (1400rpm) then idles (800 rmp) even though the car is in EV mode. I don’t think the system will allow a driving load on the a cold engine.
The reason I use a battery minder is to bring my battery up to 100%, hopefully this will make it last longer than the four years the manufacturers think.
I’ve just dropped my car off at the dealership to have the sticking handles sorted out again.
I’ve asked them to check both 12v batteries again, so it will be interesting to see the out outcome.
The last time the ICE was kicking in like this they had to change the main 12v battery.
I use the car in 80% electric mode, so I don’t think an ICE is required to charge the 12V batteries. After a month of driving in electric mode, it couldn’t be that way if only the ICE could do it.
In 2025, I filled up the tank in January, and the second time wasn’t until May/June. During that time, I’ve driven about 8,000 km without charging the 12V battery under the bonnet.