Car charging

[pacemaker82]

As I understand it I can set up PredBat to use Agile and connect to my car charging, and have predbat manage the car charging?

I set the car battery size, % target and current % in. apps.yaml, and set number of cars to 1.

I've set up all the sensors (I think) but the one that actually triggers a charge doesnt seem to be set. For my Tesla I have a sensor : "switch.charger" which gets turned on to start charging. But I have no idea how to set that up in apps.yaml.

Is that what needs to be set for "car_charging_planned" ? Or am I just misunderstanding what predbat can do here...

[springfall2008]

You need to create a HA automation that turns your car charger on and off when the Predbat slot toggles. I'd recommend that it should run every 5 minutes just in case a toggle is missed

[pacemaker82]

so does that mean the "completed_dispatches" from the Octopus API cannot be trusted as the actual billed 7.5p rate windows?

[RobinCu]

Correct, the public API only records the charge slots where the car has received charge. Octopus’ own system records all. It’s a similar reason why Octopus Compare apps etc. don’t work with IOC.

[matknowles]

So to clarify then, as long as the car accepts any charge at all, all dispatches will be billed at cheap rate? Additionally, if I were to plug in but the car is already fully charged, would I get any additional cheap rates at all?

Apologies for my confusion.

[RobinCu]

@matknowles yes, spot on. If the car charges it’s 7.5p and if the charge completes, any remaining smart slots are billed at 7.5p. Charge complete doesn’t need to be 100% SOC. I keep my in-car limit at 70% unless planning a long trip.

@pacemaker82 I might have added to the confusion by saying “correct” to your last reply (apologies I was dashing out the door and didn’t re-read before hitting reply). I meant that the Octopus API completed dispatches can’t be trusted as the complete picture but if you see a slot there it will definitely be 7.5p. They only stay on the API for about 24 hours though, so others have discussed a way to write them to a files. The point is that the extra slots where the car didn’t charge are still 7.5p.

I experienced all this confusion and unknowns. Screenshotting the Octopus app, etc for a few days. but after a couple of months of bills where 98-99% of usage is at 7.5p/kWh, you soon put your trust and just enjoy it. You can also request an interim bill from Octopus to double check. The best way is via Twitter/X.

To be clear though for anyone referring to this in the future, the above only applies to charger-based IOG interventions like the Zappi. Ohme has their own mechanism which seems to be different. It does make it overly complicated and results in a lot of muddled information online.

[pacemaker82]

Thanks @RobinCu - yeah exactly - its the fear - I had the same issue today, the planned dispatches were saying charge till 7.30am, and it finished at 6.45, so predbat happily carried on up to 7.30 assuming it was cheap (sounds like assuming correctly though). That 7-7.30 slot never appeared as a completed dispatch, which also adds to the fear, because the octopus integration then treats it as an expensive slot and adds up its cost appropriately. Hopefully Octopus will sort this out!

[pacemaker82]

@RobinCu wanted to confirm, got my bill today and indeed you are right, if Octopus said they were giving you a slot and they didnt use it, they still charge you at the cheap rate. So the completed dispatches are only showing when the car actually charged in a cheap slot, not the cheap slots themselves historically. This also means that the accumulation cost (and previous day cost) from the Octopus Integration from BottlecapDave is only semi-accurate as he bases the cheap slots off completed_dispatches only. I wonder how predbat is affected by that inaccuracy @springfall2008 in terms of the costs that it quotes?