Is there a 20 AMP timer for 3 pin charger

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Joined
Mar 14, 2024
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My sparky caught something just in time because the timer I had to charge my iMiEV (at the lowest KW charging rate after midnight) wasn't suitable and was actually starting to crack it's moulded case through excessive heat buildup I guess. It was the most expensive one offered at the contractor's electrical shop ($45) but still 10 amps.

My sparky said he could build a rugged timer but estimated it would cost $300 because a relay is needed to switch on the mains power or something like that.

We have 400+ Nissan Leafs on Waiheke and the vast majority have 3 pin charging. Seems like there would be a reasonable market here and in NZ for a 20 amp timer. There are a few things on AliExpress, etc. but might not meet our insurance / safety specifications.

Suggestions most welcome..
 
It would be a whole lot easier, cheaper, and kinder to the On Board Charger to switch the control pilot signal between the EVSE (AC "charger") and the car. Unfortunately, it's not as convenient.

My understanding is that switching the AC power to the on-board charger mechanically (with a switch, relay, or timer with relay) will cause a huge inductive kickback that will damage the switch/relay and eventually the on-board charger, at huge expense.

Switching the control pilot signal will stop the charge electronically, where there is a patch for the inductor's energy to be dissipated safely or sent on to the battery.
 
Why there are no timers rated above 10A: ima gonna guess that the 3-pin cords, sockets and circuits are running on 120vac out of the standard outlets with 2 vertical blades and a round ground pin.

The circuit breaker for those is rated at 15A, and by the 80% rule is good for 12A.

If you want a 20A [ruled to 16A] breaker circuit, then the outlets will have one vertical and one horizontal blade plus the ground. Not many folks have those in their homes, so not much of a market for 20A timer except commercial.

The Leaves have a built-in timer that allows setting the charge time. Unfortunately we don't have that except thru using the Remote, if the car had that option.

As with @coulomb, i don't recommend just pulling the plug or snapping the power off with a relay--seen too many failed OBCs in the troubleshooting and repair thread.

p.s. that minicab is awesome
 
I think the author of the original post refers to using a timer for starting the charging after midnight, not terminating it in the middle. So I don’t think there is any risk of using a timer for this application. It would be the same as to connect the cable first to the car and then to the outlet. The charging will anyway start the ordinary way. I actually use a timer that way for minimizing the car to sit with 100% charge overnight, set it so that the charging ends few hours before I need to drive in the morning. I use a rather cheap (probably 20 €) timer, bought in a supermarket, probably not the best possible quality, but not the AliExpress crap. It is rated for 16A continuous (not sure for how long). Charging at 8A 230 VAC is no problem, no heating.
 
I think the author of the original post refers to using a timer for starting the charging after midnight, not terminating it in the middle.
Yes, the problem is turning off, not turning on, the On Board Charger. So if you can guarantee that you'll never stop a charge with the timer, then that's fine.
 
FWIW, I'm using a similar arrangement. I got my friendly sparky to install a new 15A outdoor power socket on separate wiring back to a 20A contactor in the distribution panel. In operation I activate the contactor through my home control system at 11pm each night (when the EV discount rate kicks in) and shut it off at 6am the following morning. The cheap rate actually ends at 4am, but I'm rarely up that early and the extra time makes sure all charging and balancing is complete. Has worked very nicely so far - just have to remember not to muck about with the home control system after 11pm lest I interrupt the charge.
 
Why there are no timers rated above 10A: ima gonna guess that the 3-pin cords, sockets and circuits are running on 120vac out of the standard outlets with 2 vertical blades and a round ground pin.

The circuit breaker for those is rated at 15A, and by the 80% rule is good for 12A.

If you want a 20A [ruled to 16A] breaker circuit, then the outlets will have one vertical and one horizontal blade plus the ground. Not many folks have those in their homes, so not much of a market for 20A timer except commercial.

The Leaves have a built-in timer that allows setting the charge time. Unfortunately we don't have that except thru using the Remote, if the car had that option.

As with @coulomb, i don't recommend just pulling the plug or snapping the power off with a relay--seen too many failed OBCs in the troubleshooting and repair thread.

p.s. that minicab is awesome
Yes, In NZ like OZ and maybe the EU we have a 3 pin with the ground a wide blade. (Not a techie person, here) Nonetheless, I think , after what I heard from you chaps, I might be able to (again) use an off-the-shelf 24 hour timer rated at 15 amps to start charging at midnight and stop at 06:00 well after it should be fully charged). My old one got a bit toasted because maybe the circuit was 20 amps including the breaker of course, but the external receptacle and the timer were only 15 amps and maybe the guts of the connectors couldn't take the load? We had an interview on RNZ That didn't really answer too many questions: https://www.rnz.co.nz/national/programmes/ninetonoon/audio/2018941979/should-ev-owners-get-smarter
 
FWIW, I'm using a similar arrangement. I got my friendly sparky to install a new 15A outdoor power socket on separate wiring back to a 20A contactor in the distribution panel. In operation I activate the contactor through my home control system at 11pm each night (when the EV discount rate kicks in) and shut it off at 6am the following morning. The cheap rate actually ends at 4am, but I'm rarely up that early and the extra time makes sure all charging and balancing is complete. Has worked very nicely so far - just have to remember not to muck about with the home control system after 11pm lest I interrupt the charge.
That's a great solution, but we don't have a "contractor" option as far as I know. Thanks for the idea. D
 
I think the author of the original post refers to using a timer for starting the charging after midnight, not terminating it in the middle. So I don’t think there is any risk of using a timer for this application. It would be the same as to connect the cable first to the car and then to the outlet. The charging will anyway start the ordinary way. I actually use a timer that way for minimizing the car to sit with 100% charge overnight, set it so that the charging ends few hours before I need to drive in the morning. I use a rather cheap (probably 20 €) timer, bought in a supermarket, probably not the best possible quality, but not the AliExpress crap. It is rated for 16A continuous (not sure for how long). Charging at 8A 230 VAC is no problem, no heating.
That's really helpful. I had read some other stuff about over charging but don't think Mitsubishi build any programmable stuff into this 'Tonka' van. Nonetheless, was impressed to learn there is some sort of cooling when the battery is being charged. I learned quite a bit from the comments that follow, so am inclined to buy another 15 amp 24 hour timer and try again.. I you (all) think that's stupid let me know. Cheers from down under.. D
 
Yes, the problem is turning off, not turning on, the On Board Charger. So if you can guarantee that you'll never stop a charge with the timer, then that's fine.
Hi! I've been thinking about your point. I go to the grocery store and plug into the charger because it's free. When I get back - maybe 30-45 minutes later - I unplug. This means I am interrupting the charging process. There are heaps of people doing this, especially Nissan Leafs. Of course there are a few plugging their e-Jags, PEV-Mitsi, e-BMW, Teslas, etc. What happens when all these computer management charging algorithms are applied to their host batteries?
 
Sorry for the late reply.
When I get back - maybe 30-45 minutes later - I unplug. This means I am interrupting the charging process.
Yes, but do you do it by throwing the breaker at the side of the EVSE? No, but if you did, that would be a mechanical break, interrupting the power supply with an air gap.

What you probably do is press the button on your J1772 plug, or use your key fob to unlock your type 2 plug. Both of these signal to the car's computer to terminate the charge electronically. When the charge is terminated electronically, there is always a path for the inductor's energy to be dissipated by. There is no air gap in this case; by the time you withdraw the plug, the current has long (in electrical terms) been at zero.

So you can think of the air gap, and the resultant arc across that gap, as the source of the problem. The arc itself is bad for contacts, and the high voltage needed to overcome the air gap is bad for the electronics.
 
It would be a whole lot easier, cheaper, and kinder to the On Board Charger to switch the control pilot signal between the EVSE (AC "charger") and the car. Unfortunately, it's not as convenient.

My understanding is that switching the AC power to the on-board charger mechanically (with a switch, relay, or timer with relay) will cause a huge inductive kickback that will damage the switch/relay and eventually the on-board charger, at huge expense.

Switching the control pilot signal will stop the charge electronically, where there is a patch for the inductor's energy to be dissipated safely or sent on to the battery.
Thanks, very insightful
 
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