[Carty]

We do very little travelling at night anymore, but yesterday I had to make a very necessary journey for a relative.
The driving conditions where absolutely terrible !.
High winds, strong rain and cold.
I had just about everything running in the car due to the weather.
Heater / Head lights / Wipers and even Heated Rear Window at one point.
The short journey was about 8 miles in total and I noticed that the 12 Volt battery indicator had only ONE white bar above the central location showing for the whole trip.
In day time driving, I am use to seeing the gauge display TWO white bars above the central location showing.
When I arrived back home, I switched off each item that was running while watching the 12 Volt gauge at the same time.
As soon as I turned off the head lights, the second white bar returned on the gauge.
So, my question is :-
Is this normal practice to see battery gauge react in this way when running a large amount of 12 Volt dependant items ?.
I understand the gauge is still displaying above 12 Volts so should be okay, but wanted to know is anybody else has witnessed this condition ?.
Thanks !.

 

[Sandy]

yup sometimes it will show 1 blob over half, which is anything from 13.1v to 13.8v and sometimes it will pop up to 2 blobs over the central mark which is 14v+.

I guess its conditioning the battery? Or just not wasting power keeping it up at 14v+ when its fine at 13v. Why pull more out of the traction battery than necessary.

 

[dk6780]

As soon as I turned off the head lights, the second white bar returned on the gauge.

Surely it is what you'd expect? Certainly it would be the same on an ICE. But I am surprised that the "headlights" (by which I assume that you mean all of the outside lights) is a bigger draw than say the heater rear window.

 

[Carty]

yup sometimes it will show 1 blob over half, which is anything from 13.1v to 13.8v and sometimes it will pop up to 2 blobs over the central mark which is 14v+.

I guess its conditioning the battery? Or just not wasting power keeping it up at 14v+ when its fine at 13v. Why pull more out of the traction battery than necessary.

It is common to see it at the ONE “Blob” mark a for a brief time in the day, but within a few miles it jumps back to two “Blobs”.
I was a bit concerned last night, because it appeared to be stuck at the first “Blob” mark.

 

[Carty]

Surely it is what you'd expect? Certainly it would be the same on an ICE. But I am surprised that the "headlights" (by which I assume that you mean all of the outside lights) is a bigger draw than say the heater rear window.

I did not know “What to expect” because I have very rarely used the car at night.
This is why I asked the question of members who use their cars regularly at night.
I had already turned off the HRW about 1 mile before I returned home.
It made no impact on the 12 Volt gauge.
But as soon as I turned off the head light ( DRL’s still on ) the affect of the gauge was instant.
Turning on the head lights on a ICE car certainly increases the load on the alternator.
You can even hear the drag on the alternator when turn them on.
I have never had a 12 Volt battery state indicator on any of the ICE cars I have ever owned, so am a little unaware of what is normal and abnormal behaviour.
I have taken many normal 14.5 volt readings on a charging system of an ICE cars over the years, but on an EV it is a little different set up to what I am use to !.

 

[RicM]

Normal behaviour. Exactly as mine indicates. In day time you can switch on the headlights and it immediately drops from two blobs to one. Back on daytime running lights it soon pops back up to two blobs. You could try each of the auxiliary functions such as HVAC, rear windscreen heater, various levels of fan and temperature settings to se what drops the battery indicator to one blob.

While the HV traction battery is running and car is in ready, the 12V battery will always be charging so its nothing to worry about. Two blobs above = charging, one blob = charging and current being drawn from the 12V? If it indicates no blobs above 12V I would assume there is a fault and take it to the dealer.

 

[Carty]

Normal behaviour. Exactly as mine indicates. In day time you can switch on the headlights and it immediately drops from two blobs to one. Back on daytime running lights it soon pops back up to two blobs. You could try each of the auxiliary functions such as HVAC, rear windscreen heater, various levels of fan and temperature settings to se what drops the battery indicator to one blob.

While the HV traction battery is running and car is in ready, the 12V battery will always be charging so its nothing to worry about. Two blobs above = charging, one blob = charging and current being drawn from the 12V? If it indicates no blobs above 12V I would assume there is a fault and take it to the dealer.

Thanks @RicM .
From your detailed answer, it would appear normal then.
It’s brilliant that you can verify certain behaviour of the car with other owners in just a few hours !.
I think the HVAC uses 12 Volts to power the blower motor only and I think the drain would be fairly low.
The energy used to provide the heat to the cabin comes via the traction battery.
This will be a high demand and its effect can clearly be seen on the GOM when in use.
When almost all of the 12 Volt electrical items are in use then, it appears okay to expect only ONE “Blob” above the centre location to be active.
At a complete guess, I would assume this is around 13 to 13.5 Volts as you suggest.
As the 12 Volt demand is reduced by turning off selected items, the gauge returns to the higher status of TWO “Blobs” showing, as the traction battery is boosting the charge back into the 12 Volt battery.
This is likely to be around the 14.5 Volt mark.
Maybe if the journey had been a lot longer, it may have regained some extra juice for the 12 Volt or maybe it is designed only display in this fashion all the time at high demand times ?.
Yeah - If it had reached the centre section of the gauge ( 12 Volts only ) then this would be cause for concern, agreed !.
Thanks !.

 

[srichards]

It's worth getting a plug in voltmeter to go into the accessory socket to see what it's doing.

 

[Carty]

It's worth getting a plug in voltmeter to go into the accessory socket to see what it's doing.

Good shout !.

 

[Paul M]

this is what I bought

https://www.aliexpress.com/item/32879769329.html

a mini review: