Charging query

I've been charging at home using the 'cheap tariff' setting which has worked fine to delay the start time until 1am.

Yesterday though, for the first time I arrived back home with almost no battery charge left (4 miles range) and when I plugged in it automatically started charging. I checked my settings but nothing had changed so I couldn't understand why it started charging.

I left it charging and came back about an hour later and it had stopped after only putting a small amount of charge in (the range had gone up to 18 miles). I checked the light on the plug and it was a solid blue indicating that it was back on the 'cheap tariff' setting and sure enough when I got to the car this morning it was fully charged.

So, although this isn't really a problem, I'm just wondering if anyone else has experienced this ? Does it automatically charge if you are very low on battery up to a set minimum amount ? Can't remember reading about that in the handbook ?

Very interesting because i experienced something similar. I was observing the behaviour and reliability of the cheap tariff setting. I want to prevent to have my house installation in overload when the car is charging at 32 amps. I wanted to use this setting too. But i kept a close eye on it because i caught it charging when it did not supposed to.
So i have the cheap tariff setting to 22:00 to start, until 17:30. This prevents charging between 1730 and 2200.
Car connected to charger @1800. It did not start with charging; it did not take power.
But i had to do another unplanned drive, and came home again @20:20. And it did charge immediately! I left it charging to see what would happen and it stopped charging after 8 minutes @SOC 29%. It must have been about 25% when coming home, i am not sure. The first time @1800 it must have been about 45%.

Certainly something i am going to report with the product genius.

Thanks for the info Simon, that sounds similar to what I observed.

I'll keep an eye on it and will post in this thread if it happens again.

could it be it takes power to cool the battery (instead of taking this power from the battery). You both did some driving just before plugging it in.

Unlikely... because it doesn't do this every time. It seems it's more depended on SOC.

The battery suffers more degradation when left at a very low SOC, therefore it would make perfect sense to immediately start charging if at only 4%, and stop at maybe 20%, leaving the main charge to continue at the scheduled time. You'd think it would be documented somewhere though !

i3cam said:

The battery suffers more degradation when left at a very low SOC, therefore it would make perfect sense to immediately start charging if at only 4%, and stop at maybe 20%

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Yes, that's fine if that's what it's doing but because it's not mentioned in the handbook and nobody had previously mentioned it here it was just a bit of a surprise to me when it happened. I'll ask BMW, see what they say

I saw this yesterday as well. First time plugging in on a low state of charge and it immediately started charging.

fenlander said:

I saw this yesterday as well. First time plugging in on a low state of charge and it immediately started charging.

Click to expand...

Thanks fenlander. Did it also automatically stop before reaching max. charge ?

To be honest, I'm not sure now.

I just got home with 75% (ish) charge, plugged it in and the wallbox started to flash blue, but the car socket is a steady blue. Checking the meter it is drawing 4kW, but the dash shows the timer is set and doesn't show it charging.

What is it doing with the 4kW?

[edit]

Charging, that's what - the battery % is going up. My only theory at the moment is that because I didn't plug it in at all last night and left it at 20%ish that it's trying desperately to catch up and finish last nights charge.

Deeply confused.

Heating? or VERY powerful blue LEDs!!!!

Seems a bit worrying.

BTW the forum date/time seems to have gone mad - your post is dated Fri 24 October! And so is mine.

BrianStanier said:

Heating? or VERY powerful blue LEDs!!!!

Seems a bit worrying.

BTW the forum date/time seems to have gone mad - your post is dated Fri 24 October! And so is mine.

Click to expand...

I figure I'll leave it to hit 100% and see what it does tomorrow. It charged fine all last week, albeit using the 10A charging brick because we've only just had the Wallbox installed.

I wish there was a 'why are you doing this???' button.

OK.. another confirming experience about this: I had a long drive and came home with 11% SOC, connected to wallbox and started immediatly with charging. Stopped at 29%, just like last time. Only last time it took 8 minutes to reach 29%, this time it took 31 minutes. So it seems the cheap tariff is only "valid" or "working" above 29%.

Wasn't there another thread about some wording in the manual about performance being degraded below 30%?

Maybe 30% is some sort of magic threshold!

SanSerif said:

Wasn't there another thread about some wording in the manual about performance being degraded below 30%?

Maybe 30% is some sort of magic threshold!

Click to expand...

There's this strange paragraph in the 'Charging Vehicle' section which I've never really understood



Just thinking though, that range of 30km equates to 19 miles which is pretty much what my car stopped charging at.

I wonder what the German handbook says for this paragraph, you get the feeling something might have been lost in translation ?

Simon said:

So it seems the cheap tariff is only "valid" or "working" above 29%.

Click to expand...

Agreed, I've experienced this a couple more times since my OP and 29% seems to be the magic number that it stops charging at each time.

I never got a reply back from BMW but I'm happy enough with how it works now.