Accuracy of data returned to the App

Had an interesting one yesterday. Put the car on a 7kw charger while shopping. Cos I'm still trying to get my head around things I did a quick calculation in my head as to what the SoC % would be when I returned to the car. As I left the store I opened the app and got a status update returned showing the car was at 89%. This was a bit short of what I expected so I concluded the charger may be operating below par.

When I started the car it showed 94.5% :?:

It appeared that either the data returned wasn't current or there's a glitch somewhere. Anyone else experienced this?

Both iRemote and Connected apps show the time of the last update. From time to time the information is a bit old.

You also need to realize that the charging rate is not linear...it slows down a fair amount once it gets closer to being 'full'. Not all level 2 EVSE units are created equal, either. The car appears to limit the amount of amps going in, but the actual amount of power is the result of voltage*amps, and if the voltage is a bit lower, you won't be pumping in as many watts as you might think.

Unless you're talking about a CCS unit, an EVSE is just a power source...the charging circuit is in the car, and both of those things limit how much power can be used. A CCS unit, OTOH, is a monster, variable output DC power supply, and IS a charger.

I would add that ambient temperature can have an effect too:


Here you can see how the cooling spike during the taper part of the charge. But when running at the peak EVSE rate, we don't even see the cooling load because it is embedded in the charge.

Bob Wilson

I know about the different charging rates and wasn't expecting my estimate to be that accurate. My concern was mainly that the app returned an SoC that didn't reflect the actual SoC in the car rendering it somewhat unreliable as an information source.

I probably wrongly assumed that on opening the app, it pulled data from the car for a latest status update. Is this not the case? Does the car push data to a server somewhere which the app accesses on opening?

Gif said:

I know about the different charging rates and wasn't expecting my estimate to be that accurate. My concern was mainly that the app returned an SoC that didn't reflect the actual SoC in the car rendering it somewhat unreliable as an information source.

I probably wrongly assumed that on opening the app, it pulled data from the car for a latest status update. Is this not the case? Does the car push data to a server somewhere which the app accesses on opening?

Click to expand...

Everything indicates there is a server between the App and the car. So far, the App has always reports low compared to what I find getting in the car.

Bob Wilson

Gif said:

I probably wrongly assumed that on opening the app, it pulled data from the car for a latest status update. Is this not the case? Does the car push data to a server somewhere which the app accesses on opening?

Click to expand...

The app updates itself when it is opened, but it gets its update from a BMW server, not from one's i3. An i3 pushes data to this server when upon certain events occurring. Charging is certainly one of such events. Another event must involve driving because the charge level reported by iRemote and BMW Connected is updated while driving (periodically?), when leaving Ready state, or likely when other things happen that could change the charge level. I don't think we know how all of this works exactly, but we do know that it doesn't work as well as it could.

Thanks all

I think on balance, it works quite well most of the time. The iRemote services are pretty immediate given a decent phone signal.

I'm guessing there's just a practical limit to the frequency with which the car pushes data to the servers. That said, when charging, that's the exact time when you might need regular updates.

The odd thing is, if you actually reopen the app time and again during charging, the SoC steadily increases. This suggests there are regular updates. If there were gaps, you would see the SoC increasing in larger jumps rather than 1% at a time which mine was.

It just seemed like despite regular updates occurring, the data was perhaps 15 mins old.

Now I know there's a limit to how fast servers can process and update data but given the purpose here, that seems a bit too long.

I made a withdrawal from PayPal yesterday whilst sat at my Mac and before I could open my phone banking app (about 30 secs) the money was in my account!

I don't think it's a matter of what is possible, it's what has been programmed and designed for in the system. BMW had not adopted the latest cell technology until very recently on their newest models (maybe to make it easier on the production line for world-wide sourcing), and that could have an effect, too. They did say maybe a year ago that 'new' cars would get free, frequent, OTA map updates once they implemented the newer tech. Personally, as long as the car had enough storage, I wouldn't care if it took an hour or two or a couple of days to get the new updates...I'd like them for 'free' regardless, but alas, that's not the case. They could take away the need for a key and let people download them themselves, then upload via a USB stick, and then the car's out of the picture for OTA data loads, but they haven't. As it is, you need a key, even if you can get the data for free, and that costs you.