Ideal Charging Situation - Why can't it be done?

Toyota Rav4 EV Forum

Help Support Toyota Rav4 EV Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Kohler Controller

Well-known member
Joined
Mar 2, 2013
Messages
305
Location
Austin, TX
Instead of dwelling on the scheduled charging issues with the RAV4EV, I'd like to make a suggestion to the Tesla engineers (or other EV companies) about an ideal charger control strategy.

1. To address those customers that can take advantage of off-peak hours, have the ability to program a "Do not begin charging until after x" option.
2. Keep the feature that says when the car needs to be fully charged before the next departure.
3. In order to keep peak loads down, allow the charger to only charge at the rate necessary to meet the two constraints above, rather than just charge at full power somewhere in between. For example, instead of charging the RAV4EV at 7.2kW for 3 hours and sitting idle for 3 hours (assuming a 6 hour window), why not throttle back the charge rate to 3.6kW for 6 hours instead? This would reduce peak loads on the house and on the neighborhood transformer (once everyone in the cul-de-sac has an EV :D ).
4. Keep "charge immediately feature" at full charge rate.

I hope that EV companies in the future incorporate feature #3 listed above.
Are there any potential problems you see with this?
Are there any other features you'd like to see that would benefit your experience?
 
Kohler Controller said:
Instead of dwelling on the scheduled charging issues with the RAV4EV, I'd like to make a suggestion to the Tesla engineers (or other EV companies) about an ideal charger control strategy.

1. To address those customers that can take advantage of off-peak hours, have the ability to program a "Do not begin charging until after x" option.
2. Keep the feature that says when the car needs to be fully charged before the next departure.
3. In order to keep peak loads down, allow the charger to only charge at the rate necessary to meet the two constraints above, rather than just charge at full power somewhere in between. For example, instead of charging the RAV4EV at 7.2kW for 3 hours and sitting idle for 3 hours (assuming a 6 hour window), why not throttle back the charge rate to 3.6kW for 6 hours instead? This would reduce peak loads on the house and on the neighborhood transformer (once everyone in the cul-de-sac has an EV :D ).
4. Keep "charge immediately feature" at full charge rate.

I hope that EV companies in the future incorporate feature #3 listed above.
Are there any potential problems you see with this?
Are there any other features you'd like to see that would benefit your experience?


For the typical use case, what you've proposed sounds perfectly reasonable. Based on some assumptions, charging and timer logic may seem trivial. But you'd be surprised how complex these simple problems get when corner cases are considered.

For #3, what happens when the super off peak window is shorter than is possible to fully charge the car? Or what should happen when the EVSE available won't deliver the current the circuit says it can or is too low in capacity to fully charge in that window? Then there are things like daylight savings. Or in my case, Sundays (which all my failures seem to fall)!
 
TeCKis300 said:
For #3, what happens when the super off peak window is shorter than is possible to fully charge the car?

Or what should happen when the EVSE available won't deliver the current the circuit says it can or is too low in capacity to fully charge in that window? Then there are things like daylight savings. Or in my case, Sundays (which all my failures seem to fall)!

If off peak window is shorter than what is possible to fully charge the car using maximum EVSE power, then you shouldn't program the car for delayed start. That is an operator issue.

I'm envisioning the charger to initially come on at full power, to test the amount it has available from the EVSE and calculate from that. Then it would back off accordingly.

Why wouldn't daylight savings time be able to be handled easily? My DVR seems to update automatically just fine.
As for your troubles with Sundays, I've got nothin'.
 
Back
Top