Level 1 charger timer idea

[mgs333]

ElectricMonkey, how is the Wemo working out for you? I might get a similar setup for my garage in my rented condo (so can't install any EVSE) to take advantage of off peak rates. Thanks.

 

[bbrowncods]

The L1 vs. L2 decision is not a purely economic one. Having your Leaf tied up to the garage for 13-16 hours charging really puts a damper on when and how much you can use it.

I typically don't charge to 100% so there are times when it is nice to plug up and get 25 miles an hour charge rate (6.6 charger of course). I have done so for 30 minutes, even at peak rates, just to get that extra 10-12 miles at the end of the day to go out for dinner.

 

[mbender]

The L1 vs. L2 decision is not a purely economic one. Having your Leaf tied up to the garage for 13-16 hours charging really puts a damper on when and how much you can use it.

+1. And even though I can meet my needs charging at L1, in a location that does not present an inconvenience, what I don't like is the much lower efficiency (10% or more, I believe) of L1 vs. L2. And although this could be viewed as an economic reason (paying for electricity that doesn't end up in the battery), it's equally "environmental", in not wanting to waste energy (generated mostly by natural gas, in my case).

I'm not an engineer, but I don't see why L1 "has to be" so much less efficient than L2. Maybe I'll look further into in other posts, but if someone wants to provide a quick explanation here, it might save me and others time and energy searching (i.e., you'll be increasing efficiency in a different way ;-)).

 

[dgpcolorado]

...I'm not an engineer, but I don't see why L1 "has to be" so much less efficient than L2. Maybe I'll look further into in other posts, but if someone wants to provide a quick explanation here, it might save me and others time and energy searching (i.e., you'll be increasing efficiency in a different way ;-)).

The car has a certain amount of overhead while charging: to run the cooling pump, the electronics that work with the On Board Charger (OBC), and the like. That overhead will stay pretty much the same whether one is charging quickly or slowly.

So, if charging slowly, the overhead losses occur for a longer time per amount of charge that enters the battery than when charging more quickly. This is why charging very slowly at L1 (1.44 kW) is less efficient than charging at L2 (3.8 kW or 6.6 kW, depending on the car's OBC). And charging at 6.6 kW is a bit more efficient than charging at 3.8 kW.

Also — this is a bit subtle — charging to 100% is less efficient than charging to 80%. That is because the charge rate tapers as SOC approaches 100% but the overhead losses do not.

 

[smkettner]

I think charging overhead is about 300 watts. So how long do you want to burn that 300 watts? 3 hours or 15 hours?

 

[LeftieBiker]

I think charging overhead is about 300 watts. So how long do you want to burn that 300 watts? 3 hours or 15 hours?

In Winter I'd rather have it charge longer. In Summer it would depend on the weather.

 

[mbender]

Got it, thanks!

...I'm not an engineer, but I don't see why L1 "has to be" so much less efficient than L2. [...]

The car has a certain amount of overhead while charging: to run the cooling pump, the electronics that work with the On Board Charger (OBC), and the like. That overhead will stay pretty much the same whether one is charging quickly or slowly.

So, if charging slowly, [...]

Also — this is a bit subtle — charging to 100% is less efficient than charging to 80%. That is because the charge rate tapers as SOC approaches 100% but the overhead losses do not.

I think charging overhead is about 300 watts. So how long do you want to burn that 300 watts? 3 hours or 15 hours?

 

[smkettner]

I think charging overhead is about 300 watts. So how long do you want to burn that 300 watts? 3 hours or 15 hours?

In Winter I'd rather have it charge longer. In Summer it would depend on the weather.

Longer to what? keep the battery cooler? I would think you would want L3 and warm the battery a bit.

 

[Anonymous]

I'm not an engineer, but I don't see why L1 "has to be" so much less efficient than L2. Maybe I'll look further into in other posts, but if someone wants to provide a quick explanation here, it might save me and others time and energy searching (i.e., you'll be increasing efficiency in a different way ;-)).

The Smart ED has almost the save efficiency for L1 or L2 charging based on feedback from owners on that forum who have data loggers mining the charging data available. Approximately 8% of the current fed by the EVSE is not absorbed by the high voltage battery in either case. Smart ED has a 3.3kW L2 or 1.4kW L1 charger built in.

Thus, it isn't true that all EV's have this behavior...

 

[johnrhansen]

I think 300 watts overhead on 1.4 kw charging is sloppy design.

 

[smkettner]

L1 is not recommended by Nissan.

 

[mbender]

I think 300 watts overhead on 1.4 kw charging is sloppy design.

I agree. Even though I now understand why L1 is so much less efficient than L2, my hunch is still that it doesn't need to be that bad. 300 Watts is pretty much power -- what is it all doing that couldn't be done much more efficiently with solid-state electronics?!

 

[dgpcolorado]

I wouldn't be surprised if Nissan did tighten up the overhead on the gen 2 LEAF. But it is, perhaps, worth pointing out that cars with TMS use much greater amounts of electricity keeping the battery cool or warm. That TMS may be very useful in battery life and cold weather capacity, but it is still "overhead" that's not used to propel the car down the road. The LEAF overhead is small by comparison.

300 Watts, or whatever it really is, is pretty trivial on a new LEAF with a 6.6 kW OBC charged at L2 for a couple of hours each day. If you are really concerned about efficiency you won't be charging at L1 anyway. But, as advocates of L1 charging love to point out, the cost of the electricity wasted by charging at L1 is tiny compared to the cost of purchasing and installing a Level 2 EVSE. And they are correct.

You have options, one of which might be to skip the LEAF and buy the Smart ED mentioned above, another might be to charge the LEAF at L2 as fast as the OBC will allow. Or just ignore it and continue to charge at L1 and waste a few kWh of electricity for each full charge. Take your pick.

 

[mbender]

You have options, one of which might be to skip the LEAF and buy the Smart ED mentioned above, another might be to charge the LEAF at L2 as fast as the OBC will allow. Or just ignore it and continue to charge at L1 and waste a few kWh of electricity for each full charge. Take your pick.

Not sure if by "you" you mean me, but no, I'm happy with my newly leased 2015. Aside from needing the space, there are two big drawbacks to the otherwise alluring smart ED*: A.) It does not come with a quick charge "module", even as an option, and 2.) despite its diminutive size (and weight), it has a lower range, due to its 25% smaller battery (17.x kWh, I believe).

Oh, and my 'pick' is to use DCQC as much as possible (I'm in a good location to do so), and supplement with L1 if and when needed. Using the EZ-Charge card that came with the new lease, I have managed to fuel the great majority of my first 1400(!) miles at no expense (to me). Even though I got a good deal on the lease, I have to help defray what would otherwise be an extravagant expense for me somehow!


* I think they goofed on the marketing of this vehicle, btw. Without even going into the possibly negative connotations of "ED" (LOL), I think they should have called it the smart-ER. The 'R' could stand for Ride or Revolution, but it is definitely a smarter choice than their standard ICE model!

 

[dgpcolorado]

...I think they should have called it the smart-ER. ...

I like it!