Hi folks!

Does anyone have a chart or list of "alternator voltage vs temperature" of the old system without BMS?

Here in Austria we have 90°F / 32°C at the moment and the alternator voltage is ~14.0 V when driving and from what I read it's a little less for the ca/ca type batteries what we use these days.

The alternator is under ECM control, so outputs voltage based on what the ECM calculations require. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, the daily driver.
1972 Hillman Avenger GT, the project.

Yes, I know. It seems, that it's (only?) ambient temperature related, because voltage doesn't change with engine temperature. And there is no battery temperature sensor AFAIK.

Last battery lasted 7 years, what is OK IMHO. Was the same type as the new one.

From memory, temperature compensation on the pre-BMS systems only takes effect when the ambient temperature is below 15°C, when battery performance starts to drop off.

I'll see if I can find the document that explains it, as my memory isn' infallible. Hyundai Ioniq 5 Ultimate. The family car.
2009 Rimini Red SE TD4. Gone.
2006 Tonga Green i6 HSE. Gone.
Audi A5 convertible, the daily driver.
1972 Hillman Avenger GT, the project.

@Nodge68 Thank you for the offer.

The service manual only tells, that the ECU uses a "mathematical model" to calculate the alternator voltage. And from my observations it seems there is more included than just the ambient temperature.( I guess you meant it like this)
Maybe the ECU estimates the charging state on startup by battery voltage / voltage drop on crank or something.

So, a document would only be meaningfull if it's specific for the FL2 pre-BMS. If there is one at all.

Thank you!