Charge rate throttling

[EnerGene]

Picked up my used 2012 RAV4 this past Tuesday.

I was wondering if there is any way to throttle the charge rate when plugged into a public L2 6.6KW charger?
Why do I ask?

There are a couple of places I can charge around work but some want you out ASAP when you are fully charged.

What I want to do is guestimate how long I will be there (say 8hours) then calculate how much energy I used in KWh and calculate what my charge rate should be to be able to keep charging for the duration of my stay.

Thanks

 

[Larry_in_Seattle]

So you're basically saying you want to "use" the EVSE for an entire 8 hours and prevent anyone else from having access to it even if you actually were finished in, say, 3 hours?

 

[davewill]

Gaming the charger is uncool. Just go move the car when it's done.

Oh, and there's no way to "throttle" the car, anyway.

 

[Incredulocious]

Hmmm... did you know that there are some others of us who also need to sometimes use the public chargers?

 

[EnerGene]

So you're basically saying you want to "use" the EVSE for an entire 8 hours and prevent anyone else from having access to it even if you actually were finished in, say, 3 hours?

WOW!
You and the others are right. You didn't say it but that's a serious D1ck move.
Thanks for the subtle correction.

Excuse my noobieness on owning an EV.

 

[z3scot]

We have over 200 EVs at work and only 20 charge stations. People are surprisingly good about moving their cars when done charging. We also have some stations where 4 cars can park, so that when my car is done, another person disconnects me to charge his. That way I don't have move my car immediately when done charging.

Scott

 

[Rav4evnovato]

Regarding the subject & tactic of throttling or metering your charge rate ONLY AT MY OWN HOME. Can some of the engineering types comment on this idea: I only have a need for a full charge twice a week or so, always from home. I like to time the charges for high sun so that the house PV system can contribute the most ....(yes, easy to do in the summer). I would like to know if there are any chargers where I can set or limit the Kw at a lower rate (say around 3Kw) than the anticipated level of my PV system for that day. And, do you think this a realistic way to actually 'harvest' fuel from the solar panels, even with a grid tied system? Apologies if this has already been covered, and thank you for indulging the ideas of a hopeless tinkerer. So far I have considered this modest charging set up:

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=Ebusbar+BEV-H02A10+EV+Charger+Level+2%2C+240+Volt+

 

[smkettner]

Regarding the subject & tactic of throttling or metering your charge rate ONLY AT MY OWN HOME. Can some of the engineering types comment on this idea: I only have a need for a full charge twice a week or so, always from home. I like to time the charges for high sun so that the house PV system can contribute the most ....(yes, easy to do in the summer). I would like to know if there are any chargers where I can set or limit the Kw at a lower rate (say around 3Kw) than the anticipated level of my PV system for that day. And, do you think this a realistic way to actually 'harvest' fuel from the solar panels, even with a grid tied system? Apologies if this has already been covered, and thank you for indulging the ideas of a hopeless tinkerer. So far I have considered this modest charging set up:

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=Ebusbar+BEV-H02A10+EV+Charger+Level+2%2C+240+Volt+

Do you not have net metering for your solar? About the same in the end.

Do you have TOU rates available? This works well to sell high during the day and charge the vehicle at low night rates.

Otherwise you need to get an EVSE where the amps can be reduced or a second low amp EVSE for during the day. You need to get down to 12 amps 240 volts for 2.88 kW.

 

[n3ckf]

harvesting from a PV system is tricky, unless you have a system that tracks the sun (rare, but there are some out there).

The output of a PV system is a "bell" shaped curve and usually maxes around noon.

So for instance, on my system, i could charge at 3KW while using only "solar" power from about 10AM to 2 or 3PM every day. before and after that, output is less than 3KW. Its about 5KW at peak (its a 6KW nominal DC power system, but its on my roof so its fixed angle and azmiuth).

Tracking systems will produce roughly constant power from the point they become fully illumuniated till late in the day, becuas e they maintain a more-or-less constant angle to the sun. (less so for one axis trackers but one axis gives *most* of the benefit of 2-axis tracking). I know a few people in the central valley who have tracking mounts and you see them at public buildings (there's a large collection of them in East Palo Alto right next to highway 101)

 

[davewill]

Yes, the OpenEVSE's can have their limits set from their front panels. Also, since it's a open source system, it would even be possible to program it to either monitor the solar output, or follow a set curve of charge rates. I think at least one person did that (monitor the solar) on the LEAF forum.

 

[TonyWilliams]

Here's a clunky way to do this. Buy a JESLA with one adaptor for each amp rating. You'll need a bit of adaptor-ing yourself to make this work, with either multiple plugs on the same circuit (not code, but will work at your household) or adaptors to a single NEMA 14-50 wall outlet. I would do the former in my house.

You select the appropriate plug for how many amps you want to pull:

http://shop.quickchargepower.com/JESLA-is-THE-40-amp-J1772-portable-charging-solution-JESLA.htm

JESLA has the following plugs available for your particular wall electrical outlet. JESLA will further limit the maximum power to whatever plug is used. You don't need to know anything about electricity; it's Just-Plug-N-Charge (TM) !!!

1.4kW - NEMA 5-15 ......Standard Outlet... 12 amps ... adds 3-4 miles per hour charging

2.8kW - NEMA 6-15 ...... Air conditioners.. 12 amps ... adds 6-8 miles per hour charging

3.8kW - NEMA 5-20 ...... Motel A/C .......... 16 amps ... adds 4-6 miles per hour charging

5.7kW - NEMA 10-30......Older Dryers........ 24 amps (discontinued, adds 15-20 miles per hour charging)

5.7kW - NEMA 14-30......Newer Dryers...... 24 amps... adds 15-20 miles per hour charging

9.6kW - NEMA 14-50......RV Parks ............ 40 amps ... adds 25-30 miles per hour charging

 

[fromport]

Yes, the OpenEVSE's can have their limits set from their front panels. Also, since it's a open source system, it would even be possible to program it to either monitor the solar output, or follow a set curve of charge rates. I think at least one person did that (monitor the solar) on the LEAF forum.

Chris (driving force behind openevse) does exactly that. He only takes the reading from the home with an interface that reads the smart meter.
All "excessive" power that normally goes into the grid towards the utility is used to charge his ev's ;-)
so when the freezer/fridge kicks in, he adjusts the current.
There is a dirt cheap Wifi extension for the openevse that enables you to read & set the amps the EV is charging.
Minimum on 240 volt is 6 amps though and then in increments of 1 amp (240 watts)
So it is kind of coarse, but that is how the J1772 standard is defined
*update* spelling error fix

 

[Rav4evnovato]

Good responses & information. On with the experiment of solar-fuel harvesting for transportation between the two (4 Kw residential solar) locations, 92 miles apart. Reliable monitoring of solar generation (Enphase at one, SolarEdge at the other. Power meters (sorry, watt-hour meters) at the charging stations; charging times set for high sun (manual shut-off for no sun). OK, if this works as planned, I simply (my specialty) demonstrate near 100% fuel harvesting from the residential PV system(s) located nearly 100 miles apart. Possibly to be added later with some engineering assistance, automatic sensing and switching. WHY? Just for fun for an old, retired, Ham Operator hopefully with enough knowledge and experience to stay safe. The greater knowledge and experience provided on this site is much appreciated.