yes, this was my guess some weeks ago too, that they were holding this function to update it with the release of the mobile app. and from what i understand the iOS app was submitted a while ago, a couple nameless beta testers and telsa engineering told me the beta period ended several weeks ago, so they must be (sort of understandably) waiting for the corresponding android app to finish up v1... but we all know how many annoying variables there can be with all the flavors of android around....
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No charge timer!
- Thread starter Andrew Wolfe
- Start date
yes, this was my guess some weeks ago too, that they were holding this function to update it with the release of the mobile app. and from what i understand the iOS app was submitted a while ago, a couple nameless beta testers and telsa engineering told me the beta period ended several weeks ago, so they must be (sort of understandably) waiting for the corresponding android app to finish up v1... but we all know how many annoying variables there can be with all the flavors of android around....
That's really unfortunate because I think having the iPhone control will make a BIG improvement to the winter experience of the car. Hint, Tesla... this is winter now!
mitch672
Active Member
OpenEVSE just got delayed timers, "start at" and "stop at". I'm sure by the time any of you built one, Tesla will have released their smartphone apps and new firmware with timer support though.
kishdude
P #130
I hope that when the charge timer does finally gets released, it will figure out the lowest amperage to use. I think that battery life will be maximized if the battery is charged at a lower amperage. The car should figure out for you the lowest amperage to use automatically. For example, if I set that I want the car to be fully charged by 8AM, it is now 9PM, current battery level is 50%, and I'm connected to a NEMA 14-50 then the car should automatically lower the amperage of the charge such that it times it to complete right around 8AM. This will also be useful for all those living in cold climates since they will have a relatively warm battery when you are ready to leave in the morning.
Fully agree for cold and medium climates. But since you are in AZ, you should charge your battery in a way that the shortest possible time is spent with high SOC at high temperatures. It would be better for the pack to delay charging as much as possible, then start the A/C full blast and charge with what's left to reach target SOC shortly before the car leaves (with a pre-cooled pack).
Example: You arrive at home with 174 miles left. You plug your car with the UMC into a to a 50Amp circuit @ 240V and schedule a standard charge (90%, 238 miles) to be completed at 8am.
The car calculates that charging 64 miles requires 21kWh, and that the UMC connection can deliver 10kW. The A/C uses 3kW at full blast.
Charging begins at 4:40am with 20 minutes of A/C to cool down the pack from 95F to 50F (WAG here), using 3kW and 1kWh.
Then, at 5am, charging begins with 7kW going into the pack and 3kW to the A/C.
At 8am, charging completes with 21kWh charge added to the pack and 10kWh used by A/C operation.
Example: You arrive at home with 174 miles left. You plug your car with the UMC into a to a 50Amp circuit @ 240V and schedule a standard charge (90%, 238 miles) to be completed at 8am.
The car calculates that charging 64 miles requires 21kWh, and that the UMC connection can deliver 10kW. The A/C uses 3kW at full blast.
Charging begins at 4:40am with 20 minutes of A/C to cool down the pack from 95F to 50F (WAG here), using 3kW and 1kWh.
Then, at 5am, charging begins with 7kW going into the pack and 3kW to the A/C.
At 8am, charging completes with 21kWh charge added to the pack and 10kWh used by A/C operation.
@kishdude: Given the statements by Tesla engineers about Supercharging (90kW) not hurting the battery, I can't imagine that there's any differential impact between 10kW and 3kW in charging rate. There is, however, an increase in parasitic load: while the battery is charging, there are various pumps running. Tom Saxton did some analysis of Roadster charging and concluded that the greatest charge efficiency occurred at higher kW rates. He concludes:
I would like to set the amperage and the departure time, and have the car figure out when to start charging. This minimizes time at high SOC and provides a pre-conditioned pack.
GSP
My understanding is that's only true if there is no thermal management, if the thermal management isn't working correctly, or if the ambient temperature is outside the range that the thermal management can cope with.
strider
Active Member
+1 to Robert's post. If it drops too low you're wasting electricity and a Tesla is not like a phone or laptop that lack thermal battery mgmt. The system will not allow the batteries to get too hot regardless of how much current you offer so there is no benefit to the battery of lower charge current though there may be a benefit to the grid if everyone charged at 32A from midnight to 4:00 versus everyone charging at 80A from midnight to 1:30. I like GSP's suggestion.
I was pretty surprised too by didn't mind until I got my first electrical bill... The extra insult to injury here is how tesla continues to feature this capability on their website. I would be getting sued right now if my company listed features for my product that didn't exist. Its amazing to me that tesla isn't more upfront about this and just states this is a planned feature.
I think it will be tied to mobile app - to be released in next 10 days. For now I have lowered my charging current so that at least half of the charge happens at reduced rates, but it will be nice when the feature is deployed. I am willing to be patient. I am happy I received my car earlier rather than waiting for "all" features to be production ready.
for 2 nights i reduced the amps down to 14 once and 8 the next. based the # amps on how long to charge to standard charge by the end of the reduced rates at 6 am.
One thing i have noticed with my electric usage by the hour is, the car was showing it used about 12 kWH for the day and range was down to about 190 or so. so i figured it would use about 12 kwh to charge back to standard. my electric hourly usage is showing 3.53 to 3.60 kwh consumed each hour from midnight - 6am for a usage of just over 21 kWh. trying to figure this out? last night I set it for a standard charge at the full 40 amps to see what the total kwh used will be. it was basically the same range left and kwh used before charging. should have my numbers for last night later on tomorrow on the SCE website.
strider
Active Member
The lower the charge rate the more electricity is used as overhead to run the various pumps and things to keep the pack cool. In addition there is some charging loss. Tom Sax did an efficiency study for the Roadster and determined that 32A was optimal as far as losing the least amount to overhead. Above that rate the pumps and A/C ran more to compensate for the higher charge rate creating more heat. Lower than 32A the overhead didn't decrease any further so lowering the charge rate more means a lower percentage of wall power going into the batteries.
Note that the 32A number was for the Roadster. To my knowledge no one has done the same tests on a Model S.
mknox
Well-Known Member
Me too. Fortunately in Ontario, Canada the lowest price period is from 7 pm to 7 am (and all day weekends) so it isn't horribly inconvenient to plug in at 7 pm (or pay a little bit of a premium from whatever time you get home to 7 pm when the rate goes down).
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