Electricity Meter of Low-voltage Battery - why do I need to know this?

[jared]

On the right side of the instrument pack is what I assume is a display for the 12v battery. What does the number mean? Why do I need to worry about this? Considering its prominent position I assume should I be keeping an eye on this? Does it recharge as we drive?

 

[SteveMP]

The main battery will charge up the 12v but the 12v is also important to start the car's system up.

I did let the 12v down a bit when I was sorting out the dashcam enough for it to drop from 14 to just a little over 12.
I did start to worry that I had drained it too much but after reading here I charged as normal then switched the system on to then see the 12v being charged up.

 

[Jomarkh]

The 12v battery is used to start the car if you can't press ghe butoon to get it to ready mode you wont get far.
If you at a rapid leave it in ready mode to keep the 12v topped up.

 

[smokie]

I expect it was unique to the car, but once the 12v started to degrade in the Ampera the car would start to throw all kinds of errors, including some which disabled the car. The forum experts recommendation was to change the battery every three years just to avoid them,

 

[SDP79]

The read out for the 12v battery is excessive. A simple warning light similar to all other cars would do the trick!

 

[turpsey123]

Perhaps it’s something harking back to MG’s of old? Oil pressure isn’t really an option on our cars.

 

[Alb]

The read out for the 12v battery is excessive. A simple warning light similar to all other cars would do the trick!

I like engineering information.
The more the better for me.

 

[lebelinconnu]

In all honesty a massive display of the battery voltage also struck me as slightly odd when I had my test drive. Personally I would rather see the miles remaining where the 12 v display is- the current location of how many miles to go is low down and very small!

 

[EVsince2016]

A problem with EVs is that you get no warning that the battery is coming to the end of it's life.

With a fossil car you know when its a bit low when trying to start that its low & it needs replacing or charging but with an EV it just stops without warning except maybe some dash warning lights!

Brilliant idea actually.

 

[mj224]

You do get a low battery warning at about 37 miles, (ZS) and a panic warning at 10 miles. I find this very precise, much more than the a red light on a petrol tank reserve...........

 

[Kithmo]

You do get a low battery warning at about 37 miles, (ZS) and a panic warning at 10 miles. I find this very precise, much more than the a red light on a petrol tank reserve...........

On the 12v ?

 

[mj224]

On the 12v ?

Oh no, I missed which battery. Why would the 12v be of concern, Its constantly charged by the 450v.

 

[EVsince2016]

Oh no, I missed which battery. Why would the 12v be of concern, Its constantly charged by the 450v.

Because the traction battery lasts the life of the car but the 12V DC lead acid battery only has a 3-4 year life after which cells fail and it can no longer hold charge or the voltage is too low to operate systems. An ICE tells you by having trouble starting whereas an EV gives you no warning.

 

[Prof1967]

Also if you are sat charging the car with infotainment, heating etc working and are in the wrong mode the battery can drop to 12 volts or less and you will then have a problem starting the car.