ldallan
Posts: 32
Joined: Mon Jan 16, 2017 10:15 am
Delivery Date: 31 Dec 2016
Leaf Number: 000000

OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just warm?

Fri Sep 21, 2018 11:30 am

[Sorry if this has been asked before]

I've got a "Defiant Heavy Duty Timer" from Home Depot. SKU 457-864:
https://www.homedepot.com/p/Defiant-15- ... /203678095
Defiant model: GE5374-71L3
125 VAC 60 hz
15a General Purpose/Resistive
125 VAC 60 hz 1/2 HP
Made in China

With my 2015 Nissan Leaf 'S' without TechPackage and without CarWings/NissanConnect, I've found the built-in timer to be difficult to use. It can be more trouble than the hassle is worth.

I'm considering using a three-prong digital timer. It's described on the package/web-site as "Heavy Duty", but this non-electrician thinks of it as "Medium Duty". To me, two-prongs without ground would be "Light Duty".

We’re retired without a commute. Each day is different. I want to avoid charging past 90%.

The timer would go into the 110v outlet in the garage; the EVSE would plug into that; and then plug into the Leaf J-1772 connector. I wouldn’t be using the “7 Day Programmability” feature.

What could go wrong? ;-(

Rather than cross my fingers, I thought I'd check first with this forum. Do one or more of the following apply?

  • Flawed idea. Don't even try.
  • BAD IDEA!!! We're sending the fire department in advance of need.
  • Could be hard on the EVSE?
  • Should work fine, as that is something the person making the reply does.
  • Proceed Cautiously: OK if timer gets slightly warm? Also check EVSE.
  • Flawed if timer gets noticeably warm ... but can be reasonably tolerated
  • Dangerous if very warm / hot.
  • Maybe try it with a 1500 watt hair dryer first?

goldbrick
Posts: 274
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Colorado front range

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Fri Sep 21, 2018 1:34 pm

Theoretically, it should be fine. The Nissan-supplied L1 EVSE for your car is limited to 12A so it is within the 15A limit of the timer. I would also call the Leaf charge port a 'resistive' load since the on-board charger shouldn't have a large inductance (like a large motor could). So this use should be within the stated specs on the part. Worst case of course would be the unit catches fire or explodes. Probability of that depends on how well it is designed and manufactured. In this day and age I think the chances of that would be slim.

I would be just as concerned with multiple insertion cycles of the plugs so I would recommend just leaving it installed semi-permanently rather than plugging and un-plugging it often.

WetEV
Posts: 2371
Joined: Fri May 04, 2012 8:25 am
Delivery Date: 16 Feb 2014
Location: Near Seattle, WA

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Fri Sep 21, 2018 9:29 pm

ldallan wrote:
  • Flawed idea. Don't even try.
  • BAD IDEA!!! We're sending the fire department in advance of need.
  • Could be hard on the EVSE?
  • Should work fine, as that is something the person making the reply does.
  • Proceed Cautiously: OK if timer gets slightly warm? Also check EVSE.
  • Flawed if timer gets noticeably warm ... but can be reasonably tolerated
  • Dangerous if very warm / hot.
  • Maybe try it with a 1500 watt hair dryer first?


Not recommended. When the timer shuts off, the car will be drawing full current, and is going to be somewhat of an inductive load, so there will be arcing on the contacts. So your timer's life is shortened. Not good. Also, disconnecting the power is not the recommended way to shutdown the car's charger. Would be better if the charger could shutdown the current gracefully. But the charger very probably will survive this.

What you want would be an EVSE that shuts off the pilot signal, same as what happens when you unlatch the cable from the car. Low voltage, low current, tells the charger in the car to shutdown and draw no current...
WetEV
#49
Most everything around here is wet during the rainy season. And the rainy season is long.
2012 Leaf SL Red (Totaled)
2014 Leaf SL Red

DaveinOlyWA
Posts: 13337
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Sat Sep 22, 2018 8:19 am

what exactly about the LEAF charger timer is so difficult? You also really should investigate 240 volt charging options. This increases your efficiency 250% over 120 volts and is much easier to calculate charging times.
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 11,987 miles, 485 GIDs, 37.6 kwh 110.89 Ahr , SOH 96.00, Hx 115.22
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

ldallan
Posts: 32
Joined: Mon Jan 16, 2017 10:15 am
Delivery Date: 31 Dec 2016
Leaf Number: 000000

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Sat Sep 22, 2018 4:36 pm

goldbrick wrote:Theoretically, it should be fine. The Nissan-supplied L1 EVSE for your car is limited to 12A so it is within the 15A limit of the timer. I would also call the Leaf charge port a 'resistive' load since the on-board charger shouldn't have a large inductance (like a large motor could). So this use should be within the stated specs on the part. Worst case of course would be the unit catches fire or explodes. Probability of that depends on how well it is designed and manufactured. In this day and age I think the chances of that would be slim.
Interesting. Thanks.

I would be just as concerned with multiple insertion cycles of the plugs so I would recommend just leaving it installed semi-permanently rather than plugging and un-plugging it often.
Good point. I hadn't really thought this half-baked idea through.

ldallan
Posts: 32
Joined: Mon Jan 16, 2017 10:15 am
Delivery Date: 31 Dec 2016
Leaf Number: 000000

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Sat Sep 22, 2018 5:31 pm

DaveinOlyWA wrote:what exactly about the LEAF charger timer is so difficult?
On the 'S' model, my evaluation is that the built-in timer is primitive, non-intuitive, and problematic. I can expand on that.

I've used the 'S' timer about 20 or more times at free Level-2 stations at both Nissan dealers and our local utilities that has a public, free pair of charging heads. I was able to get it to work semi-reliably, but it took a pencil, paper, clipboard, and calculator. I can be slow ... my bad.

I have used the 'S' timer at 3 different ChargePoint free chargers, including several times before I got their smart-phone app. Other than being kludgy and with lots of room for improvement, I really like using the ChargePoint app. (I've submitted 3 Feature Requests.) Once, I figured out the ChargePoint app, the 'S' timer is moot.

Do you use the timer capability? On what model? 'S'? I speculate you've owned several Leafs.

You also really should investigate 240 volt charging options.
Good point. I have. However, for our (eccentric?) "use case", a home Level-2 doesn't make economic sense.

This increases your efficiency 250% over 120 volts and is much easier to calculate charging times.
We may have a different understanding of efficiency. WRT wall-clock time?

FWIW:
My impression is that Level-2 may be more efficient than Level-1 in terms of losses ... how much of 10 kwh from the "wall" actually gets into the Leaf battery. Maybe one has 10% losses and the other has 15% losses?

ldallan
Posts: 32
Joined: Mon Jan 16, 2017 10:15 am
Delivery Date: 31 Dec 2016
Leaf Number: 000000

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Sat Sep 22, 2018 5:43 pm

WetEV wrote:Not recommended. When the timer shuts off, the car will be drawing full current, and is going to be somewhat of an inductive load, so there will be arcing on the contacts. So your timer's life is shortened. Not good. Also, disconnecting the power is not the recommended way to shutdown the car's charger. Would be better if the charger could shutdown the current gracefully. But the charger very probably will survive this.
To my shame, most of that is over my head. I've got an engineering background (mech, industrial, software), but my brain doesn't seem to be wired to have more than a jr. high level of comprehension of electricity.

What you want would be an EVSE that shuts off the pilot signal, same as what happens when you unlatch the cable from the car. Low voltage, low current, tells the charger in the car to shutdown and draw no current...
Interesting.

In reflecting on the good replies I've gotten (thx!), I'm coming around to the realization that with slow Level-1 charging at home, the degree of timing precision really doesn't matter.

DaveinOlyWA
Posts: 13337
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Sat Sep 22, 2018 6:00 pm

ldallan wrote:
DaveinOlyWA wrote:what exactly about the LEAF charger timer is so difficult?
On the 'S' model, my evaluation is that the built-in timer is primitive, non-intuitive, and problematic. I can expand on that.

I've used the 'S' timer about 20 or more times at free Level-2 stations at both Nissan dealers and our local utilities that has a public, free pair of charging heads. I was able to get it to work semi-reliably, but it took a pencil, paper, clipboard, and calculator. I can be slow ... my bad.

I have used the 'S' timer at 3 different ChargePoint free chargers, including several times before I got their smart-phone app. Other than being kludgy and with lots of room for improvement, I really like using the ChargePoint app. (I've submitted 3 Feature Requests.) Once, I figured out the ChargePoint app, the 'S' timer is moot.

Do you use the timer capability? On what model? 'S'? I speculate you've owned several Leafs.

You also really should investigate 240 volt charging options.
Good point. I have. However, for our (eccentric?) "use case", a home Level-2 doesn't make economic sense.

This increases your efficiency 250% over 120 volts and is much easier to calculate charging times.
We may have a different understanding of efficiency. WRT wall-clock time?

FWIW:
My impression is that Level-2 may be more efficient than Level-1 in terms of losses ... how much of 10 kwh from the "wall" actually gets into the Leaf battery. Maybe one has 10% losses and the other has 15% losses?



amount of power from wall that does not get to your battery on 120 volts@ 12 amps; 25% . 240 volts@ 27.5 amps (or thereabouts); 10%.

I do not use timer. With 240 volts and a light driving demand, I can usually get what I need in 2 hours or less. IOW, if I need to, I plug it in when I get up in the morning and its ready to go by the time I leave for work.

But that is the advantage of 240 volts over 120 volts. You likely don't have to do much more than setting your timer to charge for two hours on 240. On 120, its now 7 hours or more.
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 11,987 miles, 485 GIDs, 37.6 kwh 110.89 Ahr , SOH 96.00, Hx 115.22
My Blog; http://daveinolywa.blogspot.com" onclick="window.open(this.href);return false;

goldbrick
Posts: 274
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Colorado front range

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Mon Sep 24, 2018 10:26 am

WetEV wrote:Not recommended. When the timer shuts off, the car will be drawing full current, and is going to be somewhat of an inductive load, so there will be arcing on the contacts. So your timer's life is shortened. Not good.


I thought of this too but I don't know if the timer has mechanical contacts or uses solid state switches. Without opening it up it's hard to tell but if it's rated for 15A then switching 12A should work. And in my extremely limited experience with this sort of thing I would still call the load resistive instead of inductive although that is a qualitative statement and I don't know the actual impedance characteristics of the on-board charger.

WetEV wrote:Also, disconnecting the power is not the recommended way to shutdown the car's charger. Would be better if the charger could shutdown the current gracefully. But the charger very probably will survive this.

What you want would be an EVSE that shuts off the pilot signal, same as what happens when you unlatch the cable from the car. Low voltage, low current, tells the charger in the car to shutdown and draw no current...


Totally agree but once again it would be good to know how the switch operates. If it is solid state it may actually ramp the current down gradually. If it's just mechanical contacts then I'd be more worried. But then any normal light switch uses mechanical contacts and they seem to last a long time with all kinds of various loads being switched on/off.

oz10k
Posts: 23
Joined: Wed Oct 18, 2017 6:29 am
Delivery Date: 18 Oct 2017
Leaf Number: 313665
Location: Northwest Chicago burb

Re: OK to use 3-prong 'medium duty' digital timer with EVSE as Leaf 'S' timer? Bad idea? Overheating? OK if gets just wa

Tue Sep 25, 2018 6:47 am

Hi Idallan,

Why not just skip using a timer? When it's low (under 40%), set it for immediate charging and plug it in early in the morning. Then if you unplug before you go to bed you'll be close to 90%. And if you forget, charging to 100% periodically is not bad.

Ron

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