goldbrick
Posts: 1090
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Boulder, CO

Re: Charging the Leaf using a step-down transformer

Wed Oct 21, 2020 11:03 am

A 20V drop is quite a lot and even at 240V it will still be a 10V drop. I'd try to charge closer to the panel or run a new supply line to the garage. Easy for me to say of course....

1byte
Posts: 11
Joined: Mon Oct 05, 2020 12:10 pm
Delivery Date: 01 Aug 2020
Leaf Number: 301105

Re: Charging the Leaf using a step-down transformer

Wed Oct 21, 2020 11:41 am

If you now have a 240 volt AC circuit near by where you park, why are you trying to still charge on 120 volts? Are both your EVSE's only 120 volt?

If so you can easily convert your OEM Nissan EVSE to 240 volt 12amp. This is what I did to mine as soon as I got it home, in fact the first at home charge I did was after I converted my OEM EVSE to 240 volts. If you are comfortable running new electrical circuits (like I am) then you 100% have the skills to do this mod.

Not the best video but pictures are worth more than words (good pictures are):
https://www.youtube.com/watch?v=QIvfiajGrR0

Now I didn't do the plug hack he did. For me it was cleaner and simpler to just put on a spare dryer cord (14-30) I already had collecting dust from a dryer long gone.

Mine more closely followed post when I did mine but I used a 22KOhm 1/4watt resistor for the plugs temp sensor (yellow wires) :
https://www.mynissanleaf.com/viewtopic.php?f=26&t=16948

In my electronics bin I found a matching 2-pin plug that the temp sensor wires from the original plug end uses, so my original plug end is uncut and could be put back together if needed (thrown in my electronics bin for now).

Per LeafSpy I get a solid 2,600+ watts into the battery pack now with no other active battery draws.
2017 Leaf - 11bars - 40,000 miles
Central Texas - SOH=77% - Hx=50% - 61.9 AHr
427QC - 647 L1/L2

dmacarthur
Posts: 207
Joined: Tue Jul 03, 2018 4:00 pm
Delivery Date: 03 Jul 2018
Leaf Number: 306556
Location: Vermont

Re: Charging the Leaf using a step-down transformer

Wed Oct 21, 2020 4:50 pm

My goal had been to charge as slowly as possible, since we rarely need much charging that can not be accomplished overnite at the lowest rate (12A 120V), using a little mechanical crank timer to get to the percentage charge we want to see (in the range of 60% plus or minus). But to try to eliminate all the line loss from this draw (about 20 V), I was trying various transformers but they draw AT LEAST .7 Amps at 240V when not in use, so.....what I have set up now is 240V NOT transformed, 15 A Duosida, which shows a voltage drop of about 20V also but this is a smaller proportion of 240V so should be more efficient. We are now experimenting with how not to overcharge- using the Leaf built-in timer we will be able to figure out, charging off-peak middle of the nite, how not to overcharge, and the Plus has that cool little button which says Charge Now which overrides the timer if we ever need to catch up.... anyway, that is the current set-up and the transformers were a rabbit hole.
2015 Leaf sold
2019 Leaf Plus S as of 9/30/19

goldbrick
Posts: 1090
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Boulder, CO

Re: Charging the Leaf using a step-down transformer

Thu Oct 22, 2020 10:38 am

I've been using L1 charging lately too and it does make predicting the final charge much easier. Another nice about the 30kWh battery, like the 1 mile per %SOC thing. When I'm down to about 20-25% I just plug it in at night and the next morning it's at 70-80% SOC. Easy peasy.

1byte
Posts: 11
Joined: Mon Oct 05, 2020 12:10 pm
Delivery Date: 01 Aug 2020
Leaf Number: 301105

Re: Charging the Leaf using a step-down transformer

Fri Oct 23, 2020 1:49 pm

I see... It took me a few days at a set charge level (L2 240volt 12amp) playing with the Leaf's (30kWh) charging departure timer to figure out the sweet spot (80% SOC). I typically leave at 7:30am on work days and so I found for me the sweet spot was setting the charge timer for a departure time of 10:50am.

Setting the depart timer for 10:50am my SOC is always around 80% come 7:30am no matter what the previous days ending SOC was. I don't sleep in on non-work or work from home days (4 kids) so it's never an issue for me to walk outside at 7:30 to unplug.

It's interesting that you are seeing a 20v drop with your 240v circuit at 15 amps. Didn't you say you just recently installed this circuit? What size wiring did you use and how far is the run?

*Wiring Police look away now*
Admittedly I'm only 25ft away from the breaker panel in my shop, but I ran 10AWG (10-4) wire in 1inch MC (metal clad) flex conduit (so lots of room\air) for my L2 27.5 amp EVSE. It's adjustable and has a voltage readout. With no load the line voltage is 242v, under a load of 27.5 amps it only drops 2 volts to 240v. I've verified the readings with a meter at the outlets output.
2017 Leaf - 11bars - 40,000 miles
Central Texas - SOH=77% - Hx=50% - 61.9 AHr
427QC - 647 L1/L2

dmacarthur
Posts: 207
Joined: Tue Jul 03, 2018 4:00 pm
Delivery Date: 03 Jul 2018
Leaf Number: 306556
Location: Vermont

Re: Charging the Leaf using a step-down transformer

Fri Oct 23, 2020 2:21 pm

1byte wrote:
Fri Oct 23, 2020 1:49 pm


It's interesting that you are seeing a 20v drop with your 240v circuit at 15 amps. Didn't you say you just recently installed this circuit? What size wiring did you use and how far is the run?

*Wiring Police look away now*
Admittedly I'm only 25ft away from the breaker panel in my shop, but I ran 10AWG (10-4) wire in 1inch MC (metal clad) flex conduit (so lots of room\air) for my L2 27.5 amp EVSE. It's adjustable and has a voltage readout. With no load the line voltage is 242v, under a load of 27.5 amps it only drops 2 volts to 240v. I've verified the readings with a meter at the outlets output.
Yup you got it right, the wire is way undersized since we never anticipated charging an electric vehicle in the garage, probably 300 feet from the house..... so trying now to find a 240V EVSE that charges at the lowest rate to minimize the line loss. First world problems but glad to have them.....
2015 Leaf sold
2019 Leaf Plus S as of 9/30/19

goldbrick
Posts: 1090
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Boulder, CO

Re: Charging the Leaf using a step-down transformer

Fri Oct 23, 2020 3:13 pm

I'm not an electrician but at 300' I think there are separate calculations required by most codes to size wires to prevent voltage loss.

That's quite a run and quite a voltage drop. I assume the line is direct buried?

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