EVSE set duration possible?

[ChuckNorris]

Newbie here, so I don't know if this is a crazy question.

I've been looking for a EVSE that can allow me to set the duration of charge or preferably set a target battery charge? Is there anything available now that can do this?

I mainly charge at work and just want to charge enough buffer to get me to work the next day. So maybe 2-3 hours with 110v is enough.

I know there are options like delayed charging but it would want to charge to full which I don't need. I also read that Ravcharge and some EVSEs can set start time(so I can do the math to get it to do the few hours before I leave for work) but it would be nice just to be able to set it up so it knows either my battery capacity and get me to my target charge level or just let me set a start time and duration/stop time.

Since i'm looking to build or buy an EVSE, I was hoping this feature is available with one in the market or if anyone has any other ideas please chime in!

Thanks!

 

[miimura]

The RAV4 EV cannot do this. Tesla Model S can set a target charge level. The only way I can think of to do exactly what you asked for is to set a single weekend departure time in the vehicle timer. Then, when you get home, check your SOC in RavCharge, calculate the charging time you need, subtract from your departure time, and set the RavCharge start time. That sounds like a lot of work just to avoid paying a little bit extra on your home electric bill. I would say, just set RavCharge for 4 hours before departure if you think 2-3 hours will usually be enough. On a 120V plug, the monthly cost difference between 2 hours and 4 hours per day is really not much.

 

[TonyWilliams]

I have a timer on my www.OPENevse.com, which is set to energize at 0004 and off at 0456.

If you are building, I recommend this route.

 

[fooljoe]

I've been asked this question (in various forms) several times, and while it's theoretically possible, unfortunately there's no easy solution. A service like RavCharge can remotely start your charge, and since it has access to your SOC it can dynamically modify your start time based on it, but unfortunately it has no power to stop your charge. The only way to stop the charge is with the EVSE (or by simply unplugging.)

What's currently missing is the interface between RavCharge and the EVSE. It shouldn't be that hard to construct such an interface, but there's just not much demand for it yet. The Juicebox has optional wifi capability, and I know it has some sort of remote interface since they are (or will be) running a pilot program where they remotely control charging in response to grid conditions. Anyone could add a wifi chip to an openEVSE, but it would take some work to get the necessary software running.

Anyway, if you're really determined to get this working I could probably help you get set up. One solution would be a "hard stop" timer on your EVSE in concert with a dynamically-set start time in RavCharge (I'd need to add this feature to RavCharge, however.) Or actually you could probably even just use the car's departure timer to do this, since it will start your charge based on your SOC; it'll just take some trial and error.

 

[ChuckNorris]

Thanks for the great responses.

TonyWilliams, for your OpenEVSE w timer, are you setting the time duration using firmware or a electromechanical timer? I noticed that there is an option for the display LCD with real time clock, I definitely need to study more of the OpenEVSE documentation and custom builds, but would someone be able to access the system clock on the OpenEVSE board and program a clock/timer feature in?

I would prefer to use the firmware to control it but if not I am looking at going the mechanical route and adding a Electromechanical Timer such as this one:
http://www.zoro.com/i/G0428382

Does anyone know if this would work straight on by putting this after my 50A Fuse panel breaker and before my NEMA 14-50P plug? Largest Timer I can find is rated at 40A , is this ok or too low?
I don't like these timers since they noise of the ticking but if it's in the garage it should be bearable.

Thanks!

 

[miimura]

While we're dreaming here, I have and idea. Purely theoretical, but likely possible.

Required Hardware:
OBD Bluetooth module in the car
Bluetooth capable embedded controller in the EVSE
Smartphone with Bluetooth and custom app for configuration

The app would set the schedule for charging and the target SOC and pass the config to the controller via Bluetooth. The OBD module would pass the SOC info to the controller via Bluetooth and the EVSE could start and stop charging at the appropriate times. Because the controller would have near real time feedback of the SOC, it would be able to learn the real charging rate, so it could adjust its start/stop time calculations or dynamically change the charge current via the pilot signal.

 

[ehelmholtz]

....would someone be able to access the system clock on the OpenEVSE board and program a clock/timer feature in? I would prefer to use the firmware to control it.

Chuck,
Welcome to the forum. I've been away from the forum for awhile but found sometime today to get back on so let me answer some of your questions. As you know, OpenEVSE is an open source fully J1772 compliant EVSE (many commercial EVSEs are not fully compliant). You're quite right that the LCD with RTC can be used to set timers by making changes to the firmware with a push button. Here's a couple of examples of portable 40A OpenEVSE with the LCD c RTC and push button control:

I took some pictures of how the Date and Time function as well as timer functions are set. Time is kept with military 24 hour setup and a battery.

As you can see the OpenEVSE with LCD RTC allows features to be set quite easily using a button. Incidentally, other features can be set in this way including ground check, L1/L2 detection, diode check etc but the most important adjustable setting is current; the examples above allow current changes from 6-40A in steps of 1-2A(this can be customized to your needs). No other portable EVSE allows for this level of flexibility.

Here's a thread about the OpenEVSE with more examples of various OpenEVSE builds: http://www.myrav4ev.com/forum/viewtopic.php?f=9&t=1013

 

[fooljoe]

While we're dreaming here, I have and idea. Purely theoretical, but likely possible.

Required Hardware:
OBD Bluetooth module in the car
Bluetooth capable embedded controller in the EVSE
Smartphone with Bluetooth and custom app for configuration

The app would set the schedule for charging and the target SOC and pass the config to the controller via Bluetooth. The OBD module would pass the SOC info to the controller via Bluetooth and the EVSE could start and stop charging at the appropriate times. Because the controller would have near real time feedback of the SOC, it would be able to learn the real charging rate, so it could adjust its start/stop time calculations or dynamically change the charge current via the pilot signal.

Yup I had this same thought not long after writing my last post. Once we get an SOC meter (either hardware or smartphone/obd reader combo) it would be awesome if it could communicate with your EVSE. It's certainly doable; it's just that nobody (that I know of) has done it yet. And it would certainly be more streamlined than trying to get SOC data via Entune out to the internet then back to your EVSE.

 

[TonyWilliams]

Thanks for the great responses.

TonyWilliams, for your OpenEVSE w timer, are you setting the time duration using firmware or a electromechanical timer? I noticed that there is an option for the display LCD with real time clock, I definitely need to study more of the OpenEVSE documentation and custom builds, but would someone be able to access the system clock on the OpenEVSE board and program a clock/timer feature in?

I would prefer to use the firmware to control it but if not I am looking at going the mechanical route and adding a Electromechanical Timer such as this one:
http://www.zoro.com/i/G0428382

Does anyone know if this would work straight on by putting this after my 50A Fuse panel breaker and before my NEMA 14-50P plug? Largest Timer I can find is rated at 40A , is this ok or too low?
I don't like these timers since they noise of the ticking but if it's in the garage it should be bearable.

Thanks!

Using a mechanical "spa" type timer to disconnect the EVSE under load is not a very elegant solution. I know that there are 50 amp ones out there. One solution, if you really want a clunky timer, is to use our "timer edition" J1772 plug and cable.

Since we run extra communications wires in our cables (there are three 18-20 gauge wires), you can switch the pilot on and off, or more correctly switch the proximity from 150 ohms to 480 ohms to trigger the car to stop charging. Your mechanical timer could be anywhere, and need only be very low power rated. Obviously, you could use any electronic timer and relay that you want to do the same job.

My OpenEVSE uses a firmware timer that correctly stops the power consumption from the car and then opens the really while it's NOT under a load.

You can see the clock in this pic at the far right with a watch battery. Note, that my circuit card is one of the originals, and the design has been updated in the past two years.

 

[TonyWilliams]

While we're dreaming here, I have and idea. Purely theoretical, but likely possible.

Required Hardware:
OBD Bluetooth module in the car
Bluetooth capable embedded controller in the EVSE
Smartphone with Bluetooth and custom app for configuration

The app would set the schedule for charging and the target SOC and pass the config to the controller via Bluetooth. The OBD module would pass the SOC info to the controller via Bluetooth and the EVSE could start and stop charging at the appropriate times. Because the controller would have near real time feedback of the SOC, it would be able to learn the real charging rate, so it could adjust its start/stop time calculations or dynamically change the charge current via the pilot signal.

Yup I had this same thought not long after writing my last post. Once we get an SOC meter (either hardware or smartphone/obd reader combo) it would be awesome if it could communicate with your EVSE. It's certainly doable; it's just that nobody (that I know of) has done it yet. And it would certainly be more streamlined than trying to get SOC data via Entune out to the internet then back to your EVSE.

Ya, this would be REALLY easy with a Bluetooth'd SOC%.

Since that signal is ALWAYS present (even when the car is off), the only real challenge is to get the OpenEVSE to correctly handle the data. Maybe I should add Bluetooth to the Rav4 Charge Monitor features?

 

[AltPowr]

Maybe I should add Bluetooth to the Rav4 Charge Monitor features?

Hmm, that might be interesting.

 

[smkettner]

So maybe 2-3 hours with 110v is enough.

I know there are options like delayed charging but it would want to charge to full which I don't need.

You need 8 to 12 miles only? Why bother. Charge to full on L1.... Do you work a 24 hour shift?

 

[fooljoe]

Maybe I should add Bluetooth to the Rav4 Charge Monitor features?

Or maybe wifi. Then you could not only interface with a nearby EVSE but also with home PCs.

 

[miimura]

Maybe I should add Bluetooth to the Rav4 Charge Monitor features?

Or maybe wifi. Then you could not only interface with a nearby EVSE but also with home PCs.

or Zigbee for that matter. It would probably be instructive to see what the emerging smart grid standards hold and how it might integrate in the future. However, it seems that automakers are all pursuing a cloud solution for communicating any information about the car.

 

[TonyWilliams]

Maybe I should add Bluetooth to the Rav4 Charge Monitor features?

Or maybe wifi. Then you could not only interface with a nearby EVSE but also with home PCs.

Well, the concept was to link to a Bluetooth enabled EVSE to support charging to a certain SOC.

 

[TonyWilliams]

Maybe I should add Bluetooth to the Rav4 Charge Monitor features?

Or maybe wifi. Then you could not only interface with a nearby EVSE but also with home PCs.

or Zigbee for that matter. It would probably be instructive to see what the emerging smart grid standards hold and how it might integrate in the future. However, it seems that automakers are all pursuing a cloud solution for communicating any information about the car.

The Wifi and / or Zigbee solution is probably good for the EVSE.