Losing charge while car is plugged in

[AaronD]

I’m not the most frequent driver. I parked my car Saturday night and plugged it in. It charged from about 50% to 75%, the limit I have set for charging. I opened the Tesla iPhone app today and it shows my battery charge is now at 73%. It’s been plugged in this whole time. I would have expected that it would use the grid power for any stuff it needed to do and that my battery would remain at the target charge level.

Is this normal/expected?

 

[fasteddie7]

Yes. I frequently charge to 90% and overnight it will drop to 88% or so. If you leave it plugged in long enough and it drops too far it will charge back up to your desired limit. This usually happen when it’s cold but I’ve seen it in the summer also. No worries.

 

[David99]

Yes, it's normal. The car will automatically top off when the battery level has dropped a certain amount. I don't know the exact value, but it's around 5% I believe. I guess it's a safety thing to not have the power connected all the time. To keep the car at the exact charge evel the required power is very small (150-250 Watt) and the on board chargers wouid be pretty inefficient running at such a lower power thus a lot of power would be wasted. That's why I think Tesla is letting the battery drop and then top off again.

 

[Not1Drop]

Yes it is normal to drop a small amount of range overnight and ambient temp can play a part.
Think it can also depend on the generation of the car though. Since the battery and charge limits forced on our 2015 S85D last year our vehicle now runs it's cooling fans regardless of the ambient temperature for several hours after charging reducing range so while we'd expect what now passes for the new 80% it is significantly lower in the morning and we need to top it off again. Or if it drops enough, it will stop the cooling fans wait a while, top up, and then promptly start the hours long process with the cooling fans again.