What charge amperage is best?

[nr427]

Hi everyone, I have a 2015 Leaf S with quick charge package. I also have a GE Durastation in my garage. The Durastation can be set for 12, 16, 24, or 30 amps. What setting would be best for the longest battery life? All of the settings are fast enough to charge overnight, and my electric rates are the same 24 hours a day.
Thanks,
Nicholas

 

[91040]

Do not set your charging station higher than 80% of the rating of your circuit! Charging at 30A needs a 40A circuit; 24A needs a 30A circuit; 16A needs a 20A circuit; 12A needs a 15A circuit. This is because EV charging is classified as continuous use.

General opinion here is that battery life will not be affected by charging at these speeds. More important is how long it stays at higher levels of charge, especially when hot. The faster speed is electrically more efficient since there are fixed loads no matter what Amperage you use.

Hi everyone, I have a 2015 Leaf S with quick charge package. I also have a GE Durastation in my garage. The Durastation can be set for 12, 16, 24, or 30 amps. What setting would be best for the longest battery life? All of the settings are fast enough to charge overnight, and my electric rates are the same 24 hours a day.
Thanks,
Nicholas

 

[smkettner]

Set it for the highest the supply allows. Either way it is a fairly slow charge for effect on longevity.

 

[dhanson865]

Hi everyone, I have a 2015 Leaf S with quick charge package. I also have a GE Durastation in my garage. The Durastation can be set for 12, 16, 24, or 30 amps. What setting would be best for the longest battery life? All of the settings are fast enough to charge overnight, and my electric rates are the same 24 hours a day.
Thanks,
Nicholas

If you have the 3.6 KW charger then set it for 12 amps, it'll save you a few cents.

If you have the 6.6KW charger then set it for 16 or higher to save those few cents.

None of the speeds will affect battery life, just cost due to wasted energy.

 

[LeftieBiker]

If you have the 3.6 KW charger then set it for 12 amps, it'll save you a few cents.

All of the newer QC-equipped Leafs have the 6.6kw charger. That includes every S with QC.

 

[nr427]

Thanks for the responses. Just to clarify I have an 8 gauge line from my breaker panel so I'm safe up to 32 amps continuous. My car will pull up to 6.6KW from the wall witch works out to 27.5 amps. Also I live in northern Utah so we get cold in the winter and hot in the summer. I charge my car inside an attached garage that moderates the temperature somewhat. I was just wondering what setting would be best to minimize battery degradation. Am I making a big deal out of nothing?
Thanks,
Nicholas

 

[RonDawg]

If you have the 3.6 KW charger then set it for 12 amps, it'll save you a few cents.

I fail to see how dialing down the EVSE will save the OP any more money in electricity even if he had a Leaf with the slower OBC (which he does not). If anything that will mean a slightly higher bill as the ancillary systems will be running for a longer period, as the car will take longer to charge.

I agree with the other posts, set the EVSE to the highest wattage that the existing circuit will safely allow. Even if the OP had a Leaf with the slower OBC, the OP may opt for an EV with a faster OBC in the future, or may have a relative or friend with one visiting who can take advantage of the faster speed.

 

[RonDawg]

Thanks for the responses. Just to clarify I have an 8 gauge line from my breaker panel so I'm safe up to 32 amps continuous. My car will pull up to 6.6KW from the wall witch works out to 27.5 amps. Also I live in northern Utah so we get cold in the winter and hot in the summer. I charge my car inside an attached garage that moderates the temperature somewhat. I was just wondering what setting would be best to minimize battery degradation. Am I making a big deal out of nothing?

As mentioned earlier, L1 and L2 (120 and 208/240 volts respectively) charging rates don't have a noticeable impact on battery life. QC can if it's done often and/or in hot weather. As you appear to have a 40 amp circuit (can handle 32 amps continuously), go ahead and set your GE unit to its 30 amp maximum.

What is more likely to impact battery life is the charge level when the car is turned off. It's recommended to not leave the car at 100% charge for more than a day, especially in hot weather. Unfortunately Nissan removed the 80% "Long Life" setting with the 2014 model year in North America, so you either have to disconnect the EVSE early, or you have to set up your charge timers to do that automatically via some guesswork. As the Leaf S only has an end timer, it's recommended to set this as close as possible to your actual departure time, so it sits as little as possible with a full battery.

Ambient temperature though has a far greater effect than any particular method of charging.

 

[dhanson865]

If you have the 3.6 KW charger then set it for 12 amps, it'll save you a few cents.

I fail to see how dialing down the EVSE will save the OP any more money in electricity even if he had a Leaf with the slower OBC (which he does not). If anything that will mean a slightly higher bill as the ancillary systems will be running for a longer period, as the car will take longer to charge.

obviously you didn't follow the link in my signature to the other thread so I'll have to bring the other thread here.

see http://avt.inel.gov/pdf/fsev/SteadyStateLoadCharacterization2012Leaf.pdf
and http://avt.inel.gov/pdf/fsev/SteadyStateLoadCharacterization2015Leaf.pdf

The 3.6KW charger is most efficient around 2KW charging rate even though max is much higher. (note the internal charger efficiency is better down around 8 or 10 amps but I'm choosing 12 amps due to the overhead you are concerned about).

Full charge rate for the 3.6KW charger was around 88.x% (maybe 88.3 or so). Less efficient at full amps

Max efficiency for the 3.6KW charger was around 89.x% (maybe 89.5 or so). But around 12a not 16a.
Max efficiency for the 6.6KW charger was around 90.x% (maybe 90.5 or so). More amps is better on this one.

Max efficiency for the 120V with 3.6KW charger was around 86.x% (closer to 86.25 or so)
Max efficiency for the 120V with 6.6KW charger was around 78% (closer to 77.9% or so)

say the overhead waste is 300W max

the efficiency difference of the 3.3 / 3.6 KW on board charger between charging at 3.6KW and 2KW isn't more than 2%.

To compare that if we imagine 2,000 W as 100% efficient and 3.6KW as 98% efficient it is like saying it is 3724W. 3724 / 2400 = 1.55. 300W is 8% of 3724W and 12.5% of 2000W. 12.5/8 = 1.56.

So if I didn't get lost in the math too far the overhead of the charge process gives us a practical wash vs the inefficiency of the charger at full speed for the 3.3 / 3.6 KW charger.

You want to charge faster than the halfway point of 8A at 240V or 10A at 208V to avoid letting the overhead waste dominate but between there and full charging rate the difference in efficacy vs the relative percentage of overhead waste almost negate each other.

If the efficiency difference is less (which it might be) or the overhead waste is more than 300W you'd want to charge as fast as possible even on the 3.3/3.6 KW charger.


On the other hand the 6.0/6.6 KW charger gets more efficient as the percentage of overhead waste decreases amplifying the desire to charge faster. No brainer on those cars to charge as fast as you can.

give me your best guess on the waste overhead due to other systems over a 2 hour period and compare that to the waste of charging at 16a instead of 12a and see if you think it's worth it or not.

I have an open evse so I can charge at any even multiple from 6a to 32a. I can do 6, 8, 10, 12, 14, 16 with my 3.6KW charger. Which is best for summer and which is best for winter? I don't think 16a is the best in any situation other than charging speed.

 

[jjeff]

Hi everyone, I have a 2015 Leaf S with quick charge package. I also have a GE Durastation in my garage. The Durastation can be set for 12, 16, 24, or 30 amps. What setting would be best for the longest battery life? All of the settings are fast enough to charge overnight, and my electric rates are the same 24 hours a day.
Thanks,
Nicholas

As others have said, more important than charge rate(unless your talking about QC which may be harder on the battery) is the amount of time sitting at a high SOC. Following that thought it should be better to charge at the highest you can and plan on ending the charge as close to your departure time as possible. IOW it's better to charge at a higher rate that would allow you to start the charging closer to your actual departure time. As far as using your departure time timer, I've found setting it about 1hr later than I actually leave still gives me almost a full charge(or 80% if I use that option on my '13, that you don't have). I guess if you definitely needed 100% charge to be able to make your trip you might want to use your actual departure time but if your like me and don't plan on it, it wouldn't hurt if it wasn't quite up to 100%(or 80% in my case).
Another reason to use higher charge rates in the winter is if you use the pre-heat option. Using too low of a EVSE setting won't give you full heat. Not positive the maximum amps the heater(and seats and steering wheel) would draw but I've noted with a 19 amp 240v charge rate I can heat the car but it won't actual charge the battery. Not sure if a 27.5 EVSE charge rate would heat the car and also charge the car, maybe someone else knows for sure....

 

[TonyWilliams]

I recommend a 30 or 32 amp EVSE. There will be ZERO impact on the battery at any charge rate available from the J1772 inlet.

Lots of choices out there.

 

[DuncanCunningham]

Welcome Nic and hello from another person with leaf (or2) in Northern Utah.

Where did you end up getting yours?

I've got a 12 SL and 15S

 

[nr427]

Welcome Nic and hello from another person with leaf (or2) in Northern Utah.

Where did you end up getting yours?

I've got a 12 SL and 15S

Thanks, I've found a lot of good information here. I'm just north of you in Clinton, and have started to notice quite a few Leafs around town.
I bought my Leaf from Carmax with less than 1000 miles on it. I tried some of the Nissan dealers and found the sales departments are one step above pond scum.
Nicholas

 

[DuncanCunningham]

Ha ha. True. We only had a good experience with Josh at the Murray dealership. No one else would do honest transactions. Though a young guy at Ken Garff in downtown SLC was good too, but he moved on, I think