Charging, preconditioning and favourable charging period

Been reading the owners handbook and I can't recall having seen a discussion on this point. I'm not clear from reading the manual what the answer is so looking for any guidance.

I understand how the precondioning works I.e. The car starts charging and preconditioning to hit the set departure time. What if this conflicts with the settings for favourable charging I.e the time when electricity is cheap?

Or is it not possible to set both options at the same time?

For instance, if you tell the car that cheap rate tariff is 00:01 to 06:30 say but you set a departure time of 09:00. Will it get all its charging done up to 06:30 then only start preconditioning the vehicle at about 08:30 or is it not that clever?

I can only speak for me, but the car will charge during the low-cost time, but always pre-condition based on the leave time.

Gif said:

Been reading the owners handbook and I can't recall having seen a discussion on this point. I'm not clear from reading the manual what the answer is so looking for any guidance.

I understand how the precondioning works I.e. The car starts charging and preconditioning to hit the set departure time. What if this conflicts with the settings for favourable charging I.e the time when electricity is cheap?

Or is it not possible to set both options at the same time?

For instance, if you tell the car that cheap rate tariff is 00:01 to 06:30 say but you set a departure time of 09:00. Will it get all its charging done up to 06:30 then only start preconditioning the vehicle at about 08:30 or is it not that clever?

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My experience/understanding is the car always charges as soon as plugged in, EVEN if there is a departure set time, say 12 hours later.
The low rate charging time is a modifier to the "charge on plug-in." So let's say you plug in at 10pm, but have low cost set to 1a-4am then it should delay charging UNTIL 1am instead of as soon as you plug in (although I have seen this not always work, but may have been due to charge being too low and car may have been trying to charge to a safe amount of charge first). So essentially it is a delay from charing on plug-in.

The pre-conditioning is only used to temperature condition the battery (if needed) and the climate inside the car using shore power. It doesn't "set" a charge time, rather a pre-departure conditioning period.

So only unknown is what if low rate window is AFTER the departure, so there is a conflict. I do not know which takes precedent (I would assume departure but have never tested it).

If your battery is quite low (don't know the numbers), it will charge up to a certain point, then wait for your low-cost charging time to finish. If you ask it to do something outside of that low-cost window, it will, and that includes departure time stuff. Some have better control when they buy an EVSE that has some built-in network or programming capability.

jadnashuanh said:

If your battery is quite low (don't know the numbers), it will charge up to a certain point, then wait for your low-cost charging time to finish.

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Unfortunately not. If you're below around 15% SoC when you plug in, the car starts charging immediately (presumably to protect the battery from being in a low SoC for too long). It will continue until 100% without pause. If you want to use low cost (UKff peak) power, you need to stop it charging manually. I do this by unplugging and moving the car a few feet. It will then wait until the off peak period.

PhilH said:

Unfortunately not. If you're below around 15% SoC when you plug in, the car starts charging immediately (presumably to protect the battery from being in a low SoC for too long). It will continue until 100% without pause. If you want to use low cost (UKff peak) power, you need to stop it charging manually. I do this by unplugging and moving the car a few feet. It will then wait until the off peak period.

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I hear what you say but this seems an odd proposition. If you were driving an i3 without the Rex/SOC recode (standard issue in US), the car could easily be running at 6.5% SOC for a few hours before being parked and then re-run on Rex at 6.5% SOC to get to the next charger. So in the normal course of events, a low SOC for many hours could be considered "normal" driving conditions even if it is not perhaps ideal. Leaving the car standing with a low SOC from say 6pm to midnight waiting for cheap rate power would not be much worse a set of conditions so I cannot see why immediate charging would be so critical.

If it does that much damage to the battery, I'd be worried about not having the Rex maintaining SOC at 75%+ all the time but this effectively makes the car somewhat closer in nature to a PHEV than a BEV, defeats the whole idea of reducing emissions and increases the fuel costs to that seen in a normal petrol car.

The only scenario that avoids low SOC conditions for any length of time involves always having the car plugged in to a charger whenever it is parked up which is simply not a realistic prospect for most people. To avoid low SOC for a prolonged duration would mean not being able to travel any meaningful daily distance without having a guaranteed destination and home charger.

Of course it could just be that the function you describe is BMW attempting to minimise the times when the car is sat with low SOC as it is not "ideal" for the battery. Given they are warranting it for 8 years and 100k miles maybe that's their logic.

Just my twopenneth