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Discussion Starter #1
We are putting solar on our roof...tentatively scheduled mid-March. Does anyone know if a 240V EVSE charging in 4 hours uses more or less energy than the 110V charging for 8-10 hours? I am sorry if this has been discussed elsewhere. I searched, but found nothing on this. I am trying to decide if this will really be worth spending the money on.:confused:
 

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I believe I^2*R (power lost to heat) losses are the highest, so charging current is going to be largest factor. However, higher Voltage equals more power delivered to the load, so the most efficient is 240 volt / 14 amp followed by 120 volt / 8 amp which would be about the same. The latter is painfully slow, so I would recommend 240 V given the choice.
 

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I also would do 240v. Not because of less electricity but because of the convenience.

The electricity difference at 110v vs 220v is a trivial cost compared to the cost of an EVSE and installation.
 

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We are putting solar on our roof...tentatively scheduled mid-March. Does anyone know if a 240V EVSE charging in 4 hours uses more or less energy than the 110V charging for 8-10 hours? I am sorry if this has been discussed elsewhere. I searched, but found nothing on this. I am trying to decide if this will really be worth spending the money on.:confused:
See LCS-20-compared-to-12amps-120vEVSE. 240v charging has an overhead of about 12%, and is about 9% more efficient than [email protected], which has an overhead of about 22%. This is without TMS. Charging at 120v*8amps is somewhere between the two in terms of efficiency; not as efficient as 240v/3.3kw but more efficient than 120v*12amps. This is because the power overhead losses are I^2*R; power is I*V, so overhead is I*R/V. You get a lot more convenience with 240v charging; you can drive more electric miles.
 

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The less time you spend charging, the lower your charging system losses will be. Therefore 220 is slightly more efficient, but likely not enough to cover the cost of the EVSE.
 

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240V uses less, not only because of less resistive losses as a function of time, but also because the car has a fixed amount of charging overhead per unit time (something like 4 amps @ 120V)

It doesn't amount to much in the grand scheme of things, but 240V does use less power for these reasons.
 

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Yes, as said "overhead" power usage while charging.

Even it were the other way, do you really want to save a few cents or have your car charged and ready for action in 4 hrs.

L2 charging it the only way to go! Think about multiple weekend trips.
 

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We are putting solar on our roof...tentatively scheduled mid-March. Does anyone know if a 240V EVSE charging in 4 hours uses more or less energy than the 110V charging for 8-10 hours? I am sorry if this has been discussed elsewhere. I searched, but found nothing on this. I am trying to decide if this will really be worth spending the money on.:confused:
I wouldn't spend the money in an effort to save electricity. As all the other answers say, the 240V charging is more efficient - but the difference is only about half a kilowatt hour on a full charge, so you'll never make back the ~$500 that way.

I did get a portable 240V charger myself, but I got it for the faster charging rate and the convenience of leaving it plugged in in the garage and the ability to pre-condition the car with minimal battery use, not for the miniscule savings.
 

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Higher voltage allows you to push more power in a given unit of time. So 240V is more efficient. Charging losses will be proportional to the current squared times the internal resistance.

So the most efficient way to charge the Volt would be at 240V and 6 Amps (minimum current allowed by SAE J1772 standard). However at that point you are pinching watts. The differences in losses are not very significant.

So it depends on your motivation. If you are looking to save every watt despite cost benefit and convenience then a 240V 6amp system works (not common would need an EVSE with variable settings). If you are looking at saving a few watts and are looking for the convenience of faster charging and a having second EVSE on hand then go with a full L2 240V EVSE. If you are looking at cost benefit and 120V charging works for you then it might be best to just stick with the OEM 120V EVSE.
 

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Discussion Starter #10
Thanks for all of your thoughts on this. I think I should just bite the bullet and get the 240V. I do love the idea of charging multiple times in a day. Any thoughts on portable vs hardwired? I like the idea of a portable but those I've seen are rated for indoor use only. I'm sorry for being stupid here, but does "rated for indoor use" mean the entire car is out of the elements or can I still run the cord under the garage door?
 

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While the consensus on the forum is for 240 the most important reason for using 240 v 120 was not stated but is the most obvious.

If charging during the day and you wish to use electrons from your power plant then you need to of course do it during sunlight. If charging at 240 you theoretically will be charging using nothing but the electrons you produce. Whether you have installed enough wattage for charging a EV car is another matter.

However here is where I differ with others, if you are charging overnight then just charge whether it be 120 or 240, the 240 is certainly more convenient but not a necessity for the Volt the question is decided by your pocketbook and whether you wish to pay for the convenience.
 

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Thanks for all of your thoughts on this. I think I should just bite the bullet and get the 240V. I do love the idea of charging multiple times in a day. Any thoughts on portable vs hardwired? I like the idea of a portable but those I've seen are rated for indoor use only. I'm sorry for being stupid here, but does "rated for indoor use" mean the entire car is out of the elements or can I still run the cord under the garage door?
Just to add, because it has a plug doesn't make it portable. Consider it an installation where you can swap it out yourself, but my manual for my Clipper Creek, at least for larger HCS-40P model, says that it isn't considered portable and you should turn off the circuit breaker before unplugging the unit. Some of those plugs aren't designed to be used a lot, they are meant to be plugged in once and left.

Hardwired is probably a little safer, someone can't just unplug it (like a kid), but both are fine. If you want to be able to change out the unit later without calling an electrician, get a plugged version. If you are comfortable working in junction boxes I would go with hardwired.

Again, after using a 240 V I find 120 V painfully slow, especially in those cases where I get back after work and want to run an errand again later, this used to result in the engine starting on me halfway through my errand or something. With 240 V the car can be more than half charged in 2 hours, and the Volt has a slow charger.

Eric
 

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Chief Engineer, Andrew Farah was asked this very question in a Q&A session a couple years ago. I can't find the video now, but it was around plug-in Days in 2013 IIRC.

His answer was that the Volt will consume slightly less energy to charge on L2 because it only needs to run the battery thermal management system for about half the time that it would than when charging on L1. Like Clarkson Cote said above- overhead.
 
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