This Mk. 4 12v. battery.

[Bristol_Crosstar]

So how do full electric cars with no 12V battery cope with this?

Even if they didnt have a 12 volt battery its not such a problem.  They have to be plugged into a special  mains powered charging point anyway.

I do wonder if the normal AA/ RAC/ Green flag  recovery schemes cover  EV drivers who run out of charge  .If they have more than their fair share of call outs maybe they should pay extra.

We have a full electric car (Seat) and it doesn't have a 12V battery, I think that's the case with most full electrics. The only difference I can see is that the full electric car has a built-in charger whereas hybrids don't so maybe the 12v battery helps the scenario where the hybrid battery is empty in some way?

[Mellorshark]

It would be interesting to know how many weeks of standing is possible before a trickle charge is advisable,

I've always gone with 2 to 3 weeks but that has been for a 12v battery that was needed to crank a starter. Ours don't need to do that so a lower voltage may be OK ?

Page 431 of the manual "drive your vehicle for more than 30 minutes at least once every three months"

[Kremmen]

Yes, I saw that but it doesn't say which battery that protects, 12v or HV, I assume HV ? I don't think I'd like to leave the 12v alone for 3 months.

I've got a voltmeter permanently plugged into the power socket and after new year I will likely have a period of inactivity.

In the interests of science, I'm not going to charge it and see what the voltage drops to.

After my last 40 mile journey, the following day, 24hrs later it was 12.2v

[guest9814]

Yes, I saw that but it doesn't say which battery that protects, 12v or HV, I assume HV ? I don't think I'd like to leave the 12v alone for 3 months.

I've got a voltmeter permanently plugged into the power socket and after new year I will likely have a period of inactivity.

In the interests of science, I'm not going to charge it and see what the voltage drops to.

After my last 40 mile journey, the following day, 24hrs later it was 12.2v

This is not true reading of battery state of charge, when you checking voltage in power socket in ACC mode or at least unlock car you getting not true reading of battery voltage, because some car electronics already eating current from 12v battery when you unlocked car and opened and closed driver’s door, i checked now, if I unlocked car no load or very little load but once I opening driver’s door and closes it there something drawing current from 12v battery not too  big - 0.3 ampere but this lowering battery voltage, in my case from 12.5v to 12.4v and this current drawing  not goes off immediately  when you locking car .
When you enabling accessory mode you powering multimedia and some other car systems so 12.2 v is pretty good.
I will check tomorrow current in ACC mode too.

[Kremmen]

Talking of locking the car.........

I don't know if it's the same on our Jazz, but, on the Civics, the first lock just locks the car and the second lock deadlocks, and, turns off any unneeded systems. Totally shuts it down.

That was posted on the Civic forum by a Honda employee a decade ago.

When I lock mine, I touch the drivers door handle twice, or tailgate button, to always fully lock it.

[guest9814]

Dead lock  related to door locks - this not allows to someone from inside car unlock doors and not awailable on all models.
From what's i seen before battery voltage recovering fully 30 minuts after leaving car locked, on my model no sensor on hood cover so i can leave it open when car locks, if yours same and you storing car in garage you can attach voltmeter directly to battaery terminals to get "true" (i writing "true" because battery still connected to car with litle current drawing) SOC an hour  after you leawe car locked.
When i get inside my Jazz after 24h i getting reading on voltmeter in power socket similar to yours Kremmen - 12.2v
My regular jorneys everyday 20-30 minutes but if i drive without powering huge load on 12v system sometimes after 10-15 minutes car desides not to charge car 12v battery and simple keeping voltage at 12.9v (i think it rely on current sensor on battery negative terminal and when battery stopping accept charge current or there no significant load on 12v the DC-DC stepdown converter redusing voltage to float voltage arrount 13v)

[aphybrid]

From Battery charge meter topic;

"mmm, I just let the car get on with it or is there something you guys think should be of concern?"

[Derkie54]

From Battery charge meter topic;

"mmm, I just let the car get on with it or is there something you guys think should be of concern?"

Same here I just let the car get on with it and enjoy  one of the easiest cars to drive that I've ever had.
If I get issues I'll investigate although I do find this post interesting.

[Kremmen]

I agree, let the car get on with it.

My only concern is that I'm a very low milage driver now and it's not unusual for the car to be sitting idle sometimes for ~4 weeks so I'm just wondering if that is too long to leave it unattended regularly. Would that be 2 steps backwards and only 1 forwards.

At least a full CTEK gets the 12v back to full charge.

[Bristol_Crosstar]

I agree, let the car get on with it.

My only concern is that I'm a very low milage driver now and it's not unusual for the car to be sitting idle sometimes for ~4 weeks so I'm just wondering if that is too long to leave it unattended regularly. Would that be 2 steps backwards and only 1 forwards.

At least a full CTEK gets the 12v back to full charge.

Do you charge the battery while it's still connected to the car? I saw another post where doing this set the alarm off.

[Kremmen]

Yes, all still connected and no issues so far.

[Lord Voltermore]

Just tried out my new plug- in volt meter .  The car hasnt  been used a great deal recently but a reading at rest of 12.1 volts  has got me a bit concerned  . Conventional  wisdom  is that anything less than 12.4 volts can lead to sulphating which could shorten battery life.    But that  said I once had a car where the battery was still going strong at 10 years old despite having been completely flat for quite long periods more than once.
 
The Jazz  powered up  fine and voltage  immediately shot up to 14.4 volts   ,which is typical of a conventional car when the engine is running.   Interestingly when I switched off the heating fan and the engine stopped ,in EV mode  (on the driveway) the battery remained at 14.4 volts. Apparently the HV battery was charging it, independent of the engine running.

But the HV battery needs a 30 minute drive at least every 3 months to recycle and charge it up. If its often having to charge up the 12 volt battery  on infrequent short journeys in winter could this shorten the period the HV battery will remain ok?   

I also used the meter on my Diesel Yaris, which only just started last time I used it. It read less than 12 volts.  But the car started immediately with no signs of being flat.

Maybe I am worrying too much.     But I will keep an eye on it.

[Kremmen]

My Civic, after a few days standing was often ~11.8v

Still had the original battery at 8 1/2 years with no issues. I used to CTEK that after 2 or 3 weeks standing.

[guest9814]

Ok checked
In ACC mode car eating 3.37 amps from 12v battery ( multimedia still not playing anything)
If no braking pedal pressed but start button pressed twice car eating almost 8 amps !!!
I really not understand this small 35ah lead acid 12v  battery installation -  that battery can be easily drained if someone put car for an 3-4 hours in power mode (but without pressing braking pedal).

[guest9814]

In 2018 I still owned old Toyota Yaris 2001 Year make.
It has 45ah battery that already 2 years old at that time, i leaved car on parking lot for 20 days, when I back from  abroad I started engine without any problems but not checked actually what’s voltage car has at this moment.