Thanks, I can easily do that, simply by asking for a fairly small percentage to be added by 5.30 am. I don't have the slightest objection to them charging the car any time they like, IF the times they give me when they announce "we've mapped tonight's smart charge!" are the actual times when it will happen. But if they aren't reliable, then no dice. They might as well say "we'll charge your car some time, but it could be any time."
The weird thing is, different people at Octopus keep replying to me and there isn't a consistent line. Some say that the times advised should be adhered to, others aren't quite so sure, but I can't get a straight answer.
It's not just the issue of draining the home battery, it's the timing of other domestic usage. The first time I noticed this it was because I had been given a slot to start at 11 pm. I usually aim to export my home battery to end about 11.30, but on that evening I changed the setting to finish the export at 11 pm, expecting the car to start charging then, and that I could turn on the washing machine. Fortunately (a) I hadn't set the home battery to start charging at 11 pm, and (b) I actually looked at the GivEnergy app at about 11.02. Car wasn't charging.
Looked again at the Octopus app, and now the car wasn't scheduled to start charging till midnight. So there I was, with an empty home battery and half an hour still to go till the normal off-peak time kicked in. All I could do was abandon the idea of turning on the washing machine, and switch all but essential usage off for that last half-hour.
I looked back at the app several times during the late evening, and every time I looked the schedule was different. I think in fact it wasn't due to start till 2 am at one point. That's when I said, sod it, and told the Zappi to charge the car 11.30 till 5.30.
I noticed a slot timed 8.00-8.30 when I looked the last time. (The original times I'd given had been 11.00-11.30 and 11.30-5.00.) I thought, if I could rely on that, I'd put the Eddi on to heat the water then, and of course set the home battery to charge too. But I couldn't. The last thing I wanted to happen was to have the Eddi on and taking peak-price electricity because they'd changed their minds again. So I ignored it.
I thought nothing would happen in that slot anyway, because I thought the car would probably be full before then. However, it can't have been quite full, because it charged for about ten minutes starting at 8 am. Fortunately that wasn't enough to make serious inroads into my home battery - it was a very dull day with almost no solar, so I needed the battery - but if it had charged the full half hour it would have been a different story.
I just wish I could get some coherent, consistent sense out of Octopus. I explained all that in my first email to them, and got the reply that I was labouring under a misapprehension and the rest of the home electricity was not at the off-peak price during these extra charging slots, and anyway, all I had to do was to set my battery to charge 11.30-5.390.
Honestly, who are these people?