Any reason to schedule charging if you have flat rate electricity price?

[FlasherZ]

I have flat-rate electricity (9c/kwH) and do not use scheduled charging; I charge at 80A. I just don't worry about it.

 

[TexasEV]

we plug in every time the car is in the garage. generally set to charge at 10 amps, sometimes higher if we are doing a lot of driving during the day. I really like starting each day with a "full" tank, and we are looking forward to a future completely free of stops at the gas station.

Plug in every time you're in the garage, yes, but that doesn't mean you should be charging all that time. Setting the charge down to 10A is the least efficient thing you can do.

 

[KJD]

If you can, you should always charge during off-peak hours to make it easier on the utility grid. Off-peak electricity is cheaper to procure wholesale during off-peak hours, and lower costs for your utility means lower rates for you in the long run. Also, off-peak generation tends to be more efficient and uses "cleaner" parts of the generation fleet as opposed to on-demand peak units. Basically, you're doing the environment a solid when you use electricity off-peak as much as possible.

Excellent summary. Lower costs should be something we can all agree on right ?

 

[FlasherZ]

Excellent summary. Lower costs should be something we can all agree on right ?

For what it's worth, the operations manager at my co-op says their wholesale price of electricity doesn't vary based on TOD - the only thing they have to worry about is capacity on their facilities (e.g., if they're near peak somewhere on the system they have to make capital investments to carry the load). It's probably true that eventually it's a matter of capital investment shifting when you can move the load, but at this point it's pretty far removed.

 

[jerry33]

The main reason to do it is to reduce the peak load on the local transformer. There is also the bit about letting the battery stay at a lower SOC for a longer period of time during the day.

 

[Brass Guy]

As for the car, charging to 85-90% you're probably not going to experience measurable battery effect whether you schedule or not.

If you have a cold night season, scheduling your charge to finish shortly before your morning commute will ensure your battery is at operating temperature when you drive.

Otherwise, it's just how you use the grid as mentioned above.

 

[davidc18]

Why is the low charge rate a problem?

Plug in every time you're in the garage, yes, but that doesn't mean you should be charging all that time. Setting the charge down to 10A is the least efficient thing you can do.

 

[Xenius]

Why is the low charge rate a problem?

Curious on this as well.

 

[Soolim]

Curious on this as well.

Low charge rate is not a problem. It is just inefficient. Efficiency is the ratio of output power divided by input power. Output power + losses = Input power

There is a constant loss within the charger regardless of the charging rate, plus variable loss that is proportional to the charging rate. Charging at a low rate means you will charge longer, therefore the constant losses for that longer period of time results in lower efficiency.

I use UMC at home, and I charge at 40A. I program the charge to start such that it reaches the 80% charge by about 15 minutes before I leave. In this way, I keep the battery close to its optimal operating temperature to start the morning commute. It is getting colder in the morning, and this charging scheme seems to work for me.

 

[fsch]

How much real damage would I be doing to have the car sit at 90% for an extra few hours everyday?

zero. zip. zilch. just plug it in to charge every time you pull into your house. no need to schedule late night charging.

Post #2 in this thread cites articles indicating that heat and full charge are ingredients for battery degradation, and its better to keep it in the 0-50% range than in the 25-75% range. I currently maintain my SOC below 50% during the week on a Model S 85 2013 that was charged to 100% most of the time at its beginning and has a rated range of 406 km (or 252 miles) at full charge. Not sure if it is all degradation or some of it is due to battery being unbalanced. Will look into that.