TylerNV
Posts: 15
Joined: Sat Jun 25, 2022 1:36 pm
Delivery Date: 05 Jun 2022
Leaf Number: 302868

Off Grid Charging

I'm considering adding a 240V split phase inverter to my system to L2 charge my 2015 Leaf. There are some quality units out there, AIms Sigineer..however, is there any long term harm in using a Modified Sine Wave instead of a PSW? The price difference is remarkable, and it will ONLY be used to charge the car.
2015 SV 51K miles 9 bars
wwhitney
Posts: 868
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Off Grid Charging

TylerNV wrote: Wed Sep 14, 2022 3:37 pm I'm considering adding a 240V split phase inverter to my system to L2 charge my 2015 Leaf. There are some quality units out there, AIms Sigineer..however, is there any long term harm in using a Modified Sine Wave instead of a PSW? The price difference is remarkable, and it will ONLY be used to charge the car.
The following is true in theory, but I don't know enough of the specifics of the Leaf's charger to be sure it's true in practice:

If it's really just for charging the Leaf, you don't need split phase (if it makes a price difference). You could use a 240V 2 -wire inverter. You'd probably need to make one circuit conductor the grounded conductor and connect the EGC to that. And then confirm the EVSE would be OK with that system and that it's ground assurance tests would pass. That's the EVSE supply in Europe, so unless the NA Leaf charger is different, it should work with it.

Also, since the first thing the Leaf charger does with the AC input is to rectify it, I would expect the MSW inverter would be fine. But again not sure.

Cheers, Wayne
goldbrick
Posts: 1934
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Boulder, CO

Re: Off Grid Charging

I agree that a MSW is probably fine for the Leaf charger but I'd also say the only way to know for sure is to test it.

As you may know, the difference between a pure sine wave input and a modified sine wave input is that the modified sine wave input has multiple frequency components, ie it is the sum of the desired 60 Hz sine wave and other frequencies. When added together, the different frequency components distort the output so it is not a pure (60 Hz only) sine wave. The big question is what effect those other frequency components will have on the onboard charger.

Assuming the charger immediately rectifies the input power, I wouldn't worry about them since the rectifier won't be negatively affected. If there are other circuits connected to the input pins, there is a chance that something may not work entirely as expected, although I think the chances of anything being damaged are low.
coulomb
Posts: 253
Joined: Thu Oct 09, 2014 5:08 pm
Delivery Date: 07 Mar 2015
Leaf Number: 200445
Location: Brisbane, Australia

Re: Off Grid Charging

There are two issues here: the on-board charger, and the thing that so many people call a charger, really an EVSE, which has a power supply in it to power the electronics.

The latter probably won't care much about a non sine wave, as it's low power and as suggested, the first thing is rectification and smoothing, which actually works better with square waves (the peak current is lower as power flows for more than a tiny fraction of the wave cycle).

But the on-board charger (OBC) is well past the power threshold where it has to be "power factor corrected", in other words, it's expected to look like a resistive load, where the current is in phase with and proportional to the voltage. So the OBC will have a boost stage so that it can draw power even when the input voltage is low. It will be assuming that the input voltage is sinusoidal. How it reacts to a square wave with a significant fraction of the time at zero voltage is unknown. Some will work happily from a DC source. My guess is that it will work OK, but it certainly might not. OBCs are expensive, so I really would not want to risk it.

> The price difference is remarkable,
That used to be the case, but there are some fairly inexpensive pure sine wave inverters these days that are pretty reasonable quality. These days, I would just not consider modified sine wave inverters for any purpose.

For an EV only situation, I'd not bother with split phase, since the OBC doesn't want it, and it basically means duplicating the whole back end of the inverter. Some models require you to buy two 120V inverters that you can then put in series. Even if you find you want to add a little lighting or other loads at a later point, the rest of the world copes pretty well with single 240V sources, so you could always buy an appliance intended for European or Chinese markets and just modify the plug.
2012 Leaf with new battery May 2019. New to me June 2019.
SageBrush
Posts: 7627
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Off Grid Charging

I'm confused about this split phase discussion.

Just about all USA residential power is 240v split phase,
and the power pins for a USA EVSE are 120 volts each
2013 LEAF 'S' Model bought Jan 2017 from N. Cal @ 90% SOH
SOLD 7/2022 @ 83% SOH
wwhitney
Posts: 868
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Off Grid Charging

SageBrush wrote: Thu Sep 15, 2022 1:50 am Just about all USA residential power is 240v split phase,
and the power pins for a USA EVSE are 120 volts each
There are just 2 power pins. And 2 points define only a single voltage--for L2 charging, 240V (or 208V if supplied by a three phase 208Y/120V system).

So no 120V source required.

[Does anyone happen to know, if you plug the stock L1 EVSE into a receptacle with Hot/Neutral reverse, does it work OK? Or does it give a ground assurance error, because it tries to draw a small current from Neutral to Ground and that fails?]

Cheers, Wayne
SageBrush
Posts: 7627
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Off Grid Charging

wwhitney wrote: Thu Sep 15, 2022 7:40 am
SageBrush wrote: Thu Sep 15, 2022 1:50 am Just about all USA residential power is 240v split phase,
and the power pins for a USA EVSE are 120 volts each
There are just 2 power pins. And 2 points define only a single voltage--for L2 charging, 240V (or 208V if supplied by a three phase 208Y/120V system).

So no 120V source required.
That all tracks, but then what is OP asking about ?
All PV systems go through inverters that output 240v. What is OP trying to do that a PV inverter connected to the home's residential panel would not do ?
2013 LEAF 'S' Model bought Jan 2017 from N. Cal @ 90% SOH
SOLD 7/2022 @ 83% SOH
goldbrick
Posts: 1934
Joined: Tue Aug 01, 2017 3:33 pm
Delivery Date: 01 Aug 2017
Leaf Number: 311806
Location: Boulder, CO

Re: Off Grid Charging

The OP's question was if a modified sine wave inverter would work with a Leaf's OBC so they wouldn't need to buy a pure sine wave inverter.

Wayne added the thought that a single phase 240V (L1 and GND with L1 being +/- 240 wrt GND) inverter would probably also work vs the standard split-phase 240V from a residential panel (L1 and GND and L2 with L1 = -L2 and L1 and L2 being +/- 120V wrt GND). All with the caveats that it would probably work but until it's tested it is a gamble. And I know I'm mixing GND and NEUTRAL but you get the idea.
wwhitney
Posts: 868
Joined: Sat Jul 17, 2010 10:10 am
Delivery Date: 01 Apr 2011
Location: Berkeley, CA

Re: Off Grid Charging

SageBrush wrote: Fri Sep 16, 2022 2:54 pm That all tracks, but then what is OP asking about ?
All PV systems go through inverters that output 240v. What is OP trying to do that a PV inverter connected to the home's residential panel would not do ?
Grid tied PV means the grid provides the voltage waveform, the grid-tied PV inverter just has to match the grid and has no control over any parameters.

Off grid PV means the PV and/or battery inverter provides the voltage waveform, and various parameters may differ from a grid source. So the question is, as far as the EVSE and the Leaf's onboard charger working properly, which parameters matter? Which ones don't?

Cheers, Wayne
SageBrush
Posts: 7627
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Off Grid Charging

Ahh yes, now I remember.
Grid tied PV inverters are designed to match the grid frequency and phase. As a safety feature, they are designed to shut down if the match is not successful.

Thanks
2013 LEAF 'S' Model bought Jan 2017 from N. Cal @ 90% SOH
SOLD 7/2022 @ 83% SOH

Return to “Batteries & Charging”