Discrepancy between SoC in cars and on iRemote

[RJSATLBA]

I've noticed when using DC rapid CCS charge that the SoC when I return to the car is usually better than I'd expected from iRemote by up to 5% and had put this down to a lag in updating although I'd expected the servers to obtain a realtime update only when needed rather than a regular one whether needed or not. When at home I'm now making increasing use of the portable 13A charger rather than my 32A EVSE because I have PVs which are starting to give me a worthwhile surplus of up to 3kW on good days so I want to mop up the surplus whenever possible, without exceeding the surplus and causing energy to be drawn from the grid. That sometimes even means that I set the 13A charger to low if I've already got a reasonable SoC and don't need a full charge.

At such low charge rates a difference caused by any short time lag should be negligible noticeable and in any event if the servers don't obtain the SoC in real time the difference should depend on whether the server is just about to obtain an update or whether it has only just done so but I'm consistently seeing 3-5% less on the remote. Today was a good example, I'd driven a short distance locally and returned with 88.5% showing in the car but plugged in at max on the 13A, drawing 2.2kW from the rare British sunshine. On getting indoors and immediately checking the remote it was showing only 85%.

I tried an experiment yesterday, the car was plugged in at max on 13A, it had reached 100% on the remote and gone to standby very shortly before 3pm which is when my wireless timer/controller currently cuts the power to stop the car drawing power when I'm unlikely to have a surplus, unless I over-ride it. I tried over-riding 2 hours later and it immediately drew the full 2.2kW again and showed only 97% SoC on the remote, it continued for about 10 mins before starting to taper down to around 600W, when it cut out after a total of 18 mins. No preconditioning of batteries or cabin should have been involved as none was set, so as far as I can tell there was no reason for a 3% loss in two hours.

This is consistent behaviour not a one-off, does anyone have any idea what is going on?

 

[jadnashuanh]

The car does not report to the server the status on any particular timeframe. Events trigger it. It is not uncommon for me to open the app and see the last update from a day ago or so. It does update when you start the car, and when you send it a command, and when you stop it, for example, and probably when it reaches full charge.

When finishing the charge on the car, it appears that near where it thinks is the end, it will shut off, probably monitor if there's a drop in their voltage level, and then restart to top things off. Someone had indicated that some of this may be cell balancing/leveling, since not all cells are exactly alike. The computer tries to get all of them tweaked as best it can, and sometimes, stopping the charge for a bit to monitor things is what is required to do that. Once that process has finished, unless I tell it to precondition, I've not seen the EVSE turn on again once it said 100%. The batteries do hold their charge pretty well and the standby losses have been kept as small as possible.

 

[Schnort]

While the car is plugged in and charging, it'll send reports regularly (I assume, anyways; I check several times over the day and see the status update time and values change).

If you're not plugged in, it won't update (since no status is changing).

Either that, or it's 'updating' with the same values and the server just isn't recording the time because nothing has changed.