Using an timer to charge on off-peak hours

[The Waiheke Don]

I have a 2011 iMiev in New Zealand.

1. I asked my 'sparkie' to look at the expensive (15 amp) timer I was using as it looked a bit 'toasted and had a crack where the charging extension line was attached. He said the reason my timer looked a bit suspicious was because the outside, mains 3 pin receptacle wasn't rated at 20 amps i.e. it wasn't designed to receive the thick ground pin). Long story short a special timer box could be 'created' with a 15 amp timer used to trip a relay to flip a switch to connect the house power to the iMiev charging cable. ** Sorry this is question is being written by a very non technical person ** When I charge the iMiev I switch it on at midnight and some time later it stops charging. There is a big difference between peak and off-peak rates, so I wondered if it would be OK to buy another timer rated at 15 amps to see if it can take the load. My charging cable has a display that indicates a full charge uses about 8.7 kwh all up and seems to draw 13 amps. Any suggestions with many thanks, Don

 

[MickeyS70]

Hello Don
As long as you’re only planning to start the process via the timer at midnight and let the car fully charge I see no issue with your setup per se.

Problems may arise if the power to the car is cut off by the timer while still actively charging.

The car’s OBD is rated at 3.7Kwh, with a grid voltage of 230V AC the current expected would be around 16A, best to get your sparkie to measure what it actually is and then rate the circuit accordingly.
Mickey

 

[The Waiheke Don]

This is very helpful. I was thinking of having the timer kick in at Midnight and stop at 06:00 but didn't think about other issues such as you mention. I did wonder if the iMiev is programmed to stop charging at ~80% to prevent over charging / reducing the life of the battery. Do you know if it's programmed not to target 100%/
Thanks heaps, Mickey

 

[MickeyS70]

This is very helpful. I was thinking of having the timer kick in at Midnight and stop at 06:00 but didn't think about other issues such as you mention. I did wonder if the iMiev is programmed to stop charging at ~80% to prevent over charging / reducing the life of the battery. Do you know if it's programmed not to target 100%/
Thanks heaps, Mickey

Unfortunately not, it will charge to 100% and then do the balancing. But if I do the maths right 6 hours should be plenty to charge your battery even at 25% losses.

 

[MrPorcine]

Check out the Intermatic water heater timer switches. The new models are $$$ but if you can find an old mechanical one (WH40) it will work fine. It doesn't have an outdoor enclosure though. There was one on Ebay (US) in June, 2024 for $40.

 

[pbui19]

the 2011 iMiev probably has the older onboard-charger, it has been suspected that its internal fuse tends to break from sudden external AC disconnect, such as by a timer. It's more prudent to control the power via the J1772 handle trigger. If I recall correctly, the WH40 has terminals to wire as on/off and would work nicely. Else, an inexpensive xmas-string timer can be re-wired to become an on/off function (default is full 120/240vac on/off)

 

[MrPorcine]

Nice to know! The Intermatic timer I found is a DPST, 230VAC and at least 30A.
Luckily, the switch is controlled by little tabs that turn if off and on. Now that I know, I've only installed the tab that will turn the power on. The sweet time here is midnight to 3PM. Even if I forget, the car will be fully charged by the time the rates go up. All I have to do is remember to turn the power off before I connect to the car.

 

[JoeS]

Even if I forget, the car will be fully charged by the time the rates go up.

Do you really need the car fully charged? Continuously charging to 100% is quite rough on what's left of our batteries.
Ref: https://myimiev.com/threads/level-of-charge-question.5479/#post-47957

Your car should have come with a Remote so you can program the ON/OFF times. If you don't have one, perhaps you might be able to pick one up on eBay or on this site...

 

[MrPorcine]

My car did not come with a remote. Can all i-MiEVs respond to a remote? If so, interesting that I could just buy one.

I'm not planning to keep the car fully charged. I'm only trying avoid the times when my utility charges at a higher rate. If I plug in the charger in the afternoon I want to be sure the power to the charger is off until midnight.

 

[MickeyS70]

My car did not come with a remote. Can all i-MiEVs respond to a remote? If so, interesting that I could just buy one.

No, you need extra HW inside the car to use the dedicated remote.

The simplest way to make a safe timer device (if you know your way around electrical circuits) is to interrupt the CP line (12V) of your EVSE or granny charger.

See video below:

 

[JoeS]

@MickeyS70, nice hack.

@MrPorcine, the Remote was provided with all US i-MiEVs. Here's what it looks like and how to use it:
https://myimiev.com/threads/how-to-using-the-miev-remote.2780/
In that thread there are also instructions to program the Remote for your own car.

I presume you're on PG&E? I'm on tariff E-TOU-C where Peak rates start at 4pm and end at 9pm - they finally responded to the Duck Curve which predicted their dilemma. PG&E has been raising the rates on us multiple times each year over the past few years - for anyone griping about electricity costs, our Peak Summer rate is now 62¢/kWh with Off-Peak being 'only' 54¢/kWh! Thankfully, I have fully amortized solar so electricity is free for me. I have a friend in Tennessee who's griping about his rate being raised to 9¢/kWh, but every time we talk he thanks me profusely about having convinced him into getting a Tesla Model Y. Sorry for digressing but our utility is a sore point with me, especially when its CEO makes $17M/year. </Rant>

Nowadays I use the Remote to start charging in the middle of the night and time it so my charging ends in the morning with around 11-12 bars which is sufficient for our everyday driving (have a KonaEV and Tesla for out-of-area trips).

Replacement of the Remote was always horribly expensive (~$800) and last I heard it was unobtainable from Mitsubishi. You might post an ad on this forum or poke around eBay. Used prices were in the $300 range. I have a spare that I'm hoarding and not selling but could loan it to you for a few weeks if you'd like to see how you like it. It's a quirky little gadget.

 

[MrPorcine]

@MrPorcine, the Remote was provided with all US i-MiEVs. Here's what it looks like and how to use it:
https://myimiev.com/threads/how-to-using-the-miev-remote.2780/
In that thread there are also instructions to program the Remote for your own car.

I presume you're on PG&E? I'm on tariff E-TOU-C where Peak rates start at 4pm and end at 9pm - they finally responded to the Duck Curve which predicted their dilemma.

Hmmm - how do I tell if my car actually has the remote hardware? Is there a module somewhere? Maybe an outside antenna? I've been told that the car originally was sold to the city of Santa Clara (or was it the City of Sunnyvale).

I'm on PG&E rate schedule EV2-A, where the summer rate falls to 0.35 between midnight and 3PM. It's the same summer and winter. Peak rate is 0.66 summer and 0.54 winter. This is a lot more attractive than E-TOU-C, maybe you should talk to a rate specialist at PG&E. You need an EV to qualify.

My level 2 charger keeps the control wires inside the car plug. Any hack would have to be at the car end of the charging cable.

 

[MrPorcine]

I found this illustration in the 2012 owner's manual:


Can someone look and see if the "Glass antenna" is visible?

 

[MickeyS70]

Hmmm - how do I tell if my car actually has the remote hardware? Is there a module somewhere? Maybe an outside antenna? I've been told that the car originally was sold to the city of Santa Clara (or was it the City of Sunnyvale).

If it’s a North American model then according to @JoeS it’s ‘remote ready’ different story for the rest of the world though.

My level 2 charger keeps the control wires inside the car plug. Any hack would have to be at the car end of the charging cable.

I’ve done two similar hacks on a level 1 (granny) and level 2 (wall box), easiest way to do is open up EVSE (make sure power is disconnected) and access the CP wire where the cable connects to the HW.

 

[kiev]

Yes the antenna patches can be seen in the black masked portion just below the clear glass.

 

[MickeyS70]

Yes the antenna patches can be seen in the black masked portion just below the clear glass.

Interesting, they are actually also on my 2011 built I-MIEV what’s missing (at least according to CAN U11xx com errors) is the EV Remote ECU under the dash…

 

[JoeS]

...
I'm on PG&E rate schedule EV2-A, where the summer rate falls to 0.35 between midnight and 3PM. It's the same summer and winter. Peak rate is 0.66 summer and 0.54 winter. This is a lot more attractive than E-TOU-C, maybe you should talk to a rate specialist at PG&E. You need an EV to qualify.
...

Yes, I have a few EVs and would qualify, but if you have solar the EV rate does not compute because under NEM1 I want to maximize my earnings when the meter runs backwards. Your Summer EV2 Peak rate of 66¢/kWh (worse than my 62¢/kWh) is also between 4pm and 9pm but you're also exposed to Part-Peak at 55¢/kWh between 3:00pm and 4:00pm and 9:00pm and midnight, which is great if you work swing shift and aren't home. If you're home in the afternoon and evenings you might do the math as you're paying an even higher rate than I am during those times. If you have an all-electric house, the i-MiEV doesn't consume all that much energy % at 35¢/kWh. If you don't have an all-electric house you might do the math to see if PG&E Tariff E-1 might work better for you overall if you stay within Tier 1 usage. If you log into your account on their website, PG&E can even provide you with an 'analysis' comparing the various available tariffs for your use case - that numerical 'analysis' is useless in my case.

On an annual basis I am energy-positive so all I pay PG&E is their 39¢/day meter charge (which they just got the PUC to raise to $24/month next year - they wanted to hit us with three times as much!). They zero out my $1000+/year 'surplus' from my meter running backwards, whereas I get a nice check annually from my CCA, Silicon Valley Clean Energy.

Let me know if you'd like to borrow the Remote as I'll be in Redwood City on Friday evening and could drop it off to you. Use this website's 'Conversations' feature to exchange contact details.

 

[The Waiheke Don]

Nice to know! The Intermatic timer I found is a DPST, 230VAC and at least 30A. View attachment 716View attachment 715
Luckily, the switch is controlled by little tabs that turn if off and on. Now that I know, I've only installed the tab that will turn the power on. The sweet time here is midnight to 3PM. Even if I forget, the car will be fully charged by the time the rates go up. All I have to do is remember to turn the power off before I connect to the car.

Super idea. I have been manually starting the charging process at midnight and then manually turning it off with the external outlet switch around 07:00 well past when it's charged. I usually check out the interface on the charger to see how many KW were used. Nonetheless, I will now get into the habit of detaching the cable from the iMiev to off-set any issues. In the past 3 years it has gone from 68km to 58km so an 'ounce of prevention' will be applied. Thanks to all for great ideas!! Oh, very many thanks for the photos too.

 

[petere]

Hi Don
Here in Perth with 240v for many years used a simple timer a bit like this one https://www.ebay.com.au/itm/Manual-Mains-Timer-Switch-16A-240VAC-1-Year-WARRANTY/322198873612 and wired into a 15A GPO to simply charge while our solar is good - eg 8am-4pm in summer.
I've been testing 16A Tuya Zigbee (eg https://www.ebay.com.au/itm/145858043896) switches so I can control the charging using Home Assistant.
Regards
Peter
PS we love Waiheke!

 

[The Waiheke Don]

Hi Peter, I really like your suggestions and will follow up. The first idea will require a sparkie and I can have the timer shipped here. Tuya idea lifts the convenience to a new high. Apparently they won't ship to NZ, but at least I have something to search for here.
Once again, REALLY appreciate your efforts to solve my problem..
Hope to see you here some time.

Don