Will Caliban start on Monday morning?

[Rolfe]

Now at Cherwell Valley having coffee.

 

[tsedge]

While we still don't know the percentage HV SOC at which the car still charges the 12V battery, my guess is that it is quite small, probably 5%.

The 50% might possibly have been true in very early software releases, but I cannot believe it is true for the vast majority of people or we'd have dozens or hundreds of reports of 12V battery draining.

So, my guess - and it is just a guess so could be wrong - is that this was sorted out early on.

 

[securespark]

Now at Cherwell Valley having coffee.

Are you heading home?

 

[Rolfe]

Are you heading home?

Yes. Now having a (late) light lunch at Trentham Park.

 

[securespark]

Gosh. More memories!

Mrs S moved to Newcastle-u-Lyme when she was 10 and when I met her, her folks still lived there. Have visited there and also Staffs was part of my patch when I was working PAYE.

I think the M6 is my most travelled motorway. And the most travelled bit between J19 and J10. The worst bit, for me, is around the D road, J 15 and 16.

 

[dsimpkins]

The poll is still open for 21 minutes. Wonder how people will vote now?

 

[MG Clive]

The poll is still open for 21 minutes. Wonder how people will vote now?

The poll is now Weetabix or Porridge.

 

[Everest]

Or whether Caliban made it over the Hardknott pass on the way home

 

[Rolfe]

Home now. Had a small hiccup when I left him on a charger at Tebay without realising the charge hadn't properly initiated, and didn't realise until I was sitting down to a plate of lasanga. So I had to go back out into the rain and wind and get it started again. Probably lost about 20 minutes. Then the weather was atrocious most of the way home so I probably lost another ten minutes just going slowly. I identified another car going about the speed I wanted to go and latched on to him with the ACC. This continued for close on 75 miles. He probably thought I was stalking him, until I turned off at Abington and he went on. But it meant that all I had to do was steer to follow him. No hassle keeping to a speed and no need to put lights on full beam at all.

We made it over the Shap and Beattock Summit. That was enough for one evening in this weather.

 

[securespark]

Without giving away your home location, are you N, S E or W?

 

[T1 Terry]

Home now. Had a small hiccup when I left him on a charger at Tebay without realising the charge hadn't properly initiated, and didn't realise until I was sitting down to a plate of lasanga. So I had to go back out into the rain and wind and get it started again. Probably lost about 20 minutes. Then the weather was atrocious most of the way home so I probably lost another ten minutes just going slowly. I identified another car going about the speed I wanted to go and latched on to him with the ACC. This continued for close on 75 miles. He probably thought I was stalking him, until I turned off at Abington and he went on. But it meant that all I had to do was steer to follow him. No hassle keeping to a speed and no need to put lights on full beam at all.

We made it over the Shap and Beattock Summit. That was enough for one evening in this weather.

Probably gave him a thrill, a bonny young lass following close behind him ..... driving through the night in such bad weather, glad you made it home safely .... now I guess you will be sleeping all day, you people certainly have strange sleeping hrs over there

T1 Terry

 

[Everest]

Without giving away your home location, are you N, S E or W?

It's public info... Profile says...

Rolfe​

Runner-up #5
Moderator · From West Linton, Scotland
Joined Apr 10, 2023
Last seen Yesterday at 10:29 PM

 

[securespark]

DOH!
Didn't even think to look there!

 

[Rolfe]

While we still don't know the percentage HV SOC at which the car still charges the 12V battery, my guess is that it is quite small, probably 5%.

The 50% might possibly have been true in very early software releases, but I cannot believe it is true for the vast majority of people or we'd have dozens or hundreds of reports of 12V battery draining.

So, my guess - and it is just a guess so could be wrong - is that this was sorted out early on.

I think you (it was you, right?) made a good point earlier about how we (well, some of us anyway) are a bit inclined to catastrophise simply because it's all a bit new and we're not quite sure how some of it works, and someone else had a problem so maybe this happens to everyone!

I still don't really know how this works. I do know that I would not have been even faintly worried about leaving a 2½ year old petrol car parked for five nights, even though obviously its battery wouldn't have been being topped up. I think my Golf was about eight when I replaced its obviously-failing battery, and about two years later the car was parked for ten weeks in winter weather and started again with only mild reluctance (although I did have a starter pack in the car just in case). Most cars parked for the length of that cruise seemed to start OK.

So how reliant is an EV's 12v on being topped up from the traction battery when the car isn't being used? I mean, why would it need it, if the 12v was in decent condition in the first place? Maybe I had no trouble because the 12v didn't need topping up anyway in the time the car was parked.

But then, I also don't know how low the traction battery has to be before the routine topping-up stops happening. Maybe I had no trouble because the 12v is still being topped up when the traction battery is at 20% SoC. I don't know why they don't tell us, either.

The reason for the 12v to be abandoned to its fate at a low SoC of the traction battery is to save the traction battery from damage through draining too low, and to allow the car to become operational again by the simple expedient of putting on a jump start or replacing the 12v, rather than have its traction battery run out. Rationally, you'd think this is something that would apply to a long time parked up, not a few days.

We might have had no reports of a 12v draining in this way because a healthy 12v doesn't even need topping up for a few weeks, or we may have had no reports because the cut-off SoC is pretty low and nobody has left their car parked up that low. I don't know.

All I know is that when Kyle Connor rescued that 2012(?) Coda which had been abandoned for ten years, it was sitting at 30% on the (LFP) traction battery, with an apparently dead 12v. He later established that the 12v wasn't actually completely dead, but that the car only maintained its charge until the traction battery reached 30%, at which point it stopped maintaining the 12v. Of course that 12v was old and not healthy, but it did hold a charge to some extent. No idea how long it took to drain the traction battery down to 30%, or more importantly how long that would take if the 12v was in good condition.

This may be something we only find out about when it actually happens to someone. Someone leaves a car sitting at under 10% for a few weeks (not advisble) and comes back to a flat 12v. Maybe it will never happen.

 

[Everest]

The big difference though is that for an ICE vehicle the 12V battery is needed to crank the engine, which will draw a huge current, especially with in a diesel engine, as well as run the vehicle's electronics. With an EV, the 12V battery only needs to power the electronics enough to put the car into 'ready' mode. Hence - in theory - should be good to be left a bit longer.

Having said that any LA battery will have a degree of self-discharge and unlike LFP or NMC batteries, a lead-acid battery should not be discharge to more than 50% of its capacity. Hence, I'd say you're looking at max of 3 months for it to be in a state to crank a petrol or diesel engine.

 

[tsedge]

The big difference though is that for an ICE vehicle the 12V battery is needed to crank the engine, which will draw a huge current, especially with in a diesel engine, as well as run the vehicle's electronics. With an EV, the 12V battery only needs to power the electronics enough to put the car into 'ready' mode. Hence - in theory - should be good to be left a bit longer.

Yes, this is a crucial point. EVs have a far gentler load than ICE engines on the 12V battery, and they are topped-up in a different way.

Therefore I believe all the good advice about ICE 12V voltages and best practice etc... doesn't apply - it is a quite different use case.

There's plenty of reasons to believe that generally-speaking EV 12V batteries will last a lot longer than ICE ones, so long as there are no phantom drains happening.

Having said that any LA battery will have a degree of self-discharge and unlike LFP or NMC batteries, a lead-acid battery should not be discharge to more than 50% of its capacity. Hence, I'd say you're looking at max of 3 months for it to be in a state to crank a petrol or diesel engine.

Which is I think why MG recommend disconnecting the 12V battery if you are leaving the vehicle for a month or longer.