Ingineer
Well-known member
Generally no more than 16.5a.rawhog said:
-Phil
Leaf Charging Efficiency - Lab Test (and Idle power draw)
- Thread starter Ingineer
- Start date
Help Support My Nissan Leaf Forum:
-Phil
Nekota
Well-known member
An estimate for the motor torque constant is 1.4 Nm/amp and would like to confirm if anyone has a more accurate value or actual measurement.
Ingineer said:
Thanks for starting this thread. I had my suspicions about the accessory power meter, but you've pretty much confirmed it for me.
Also, I realize that the power that just the vent fans (climate control off) draw is low, but I would expect at least the tiniest amount to show on the meter. Any idea on what amount the vent fans actually draw?
TomT
Well-known member
Ahh! THAT explains why I have never seen the numbers I expected under different scenarios...
Ingineer said:
KillaWhat
Well-known member
I Just LOVE this forum!!
Ingineer said:
DaveinOlyWA
Well-known member
KillaWhat said:
Like YA!! it s not hard to see why. its like having our own personal Leaf Engineer on hand expect i am beginning to suspect Phil might be able to teach them a few things as well
DaveinOlyWA
Well-known member
any thoughts on repeating measurements at different temps? be interested to see how the values change when temp is say 100 verses early spring when you did it and it was what?? 70?
What about direct charging with ~400v DC using Solar PV array?
(Thus avoiding DC to 120/220v AC, then back to DC losses)
I know this could be very $$$, but from a technical point of view, is this feasible?
A few thoughts:
* Most modern PVs can operate on 600V+ series connection.
* Use a bank of Super caps to stabilize PV system voltage.
* Use a DC to DC inverter to produce a DC charging voltage that the Leaf would like.
*Option 1) The DC/DC inverter would maintain the (Leaf required) DC voltage & Amps but drop out if Voltage or Amps could not be maintained
*Option 2) The DC/DC inverter would maintain the (Leaf required) DC voltage but vary the Amps delivered.
A) What DC charging voltage (& tolerance) does the Leaf like?
B) What DC charging Amps (& tolerance) does the Leaf like?
C) i.e. what threshold will Leaf ~400v dc port allow power in (& disallow power in)?
(Thus avoiding DC to 120/220v AC, then back to DC losses)
I know this could be very $$$, but from a technical point of view, is this feasible?
A few thoughts:
* Most modern PVs can operate on 600V+ series connection.
* Use a bank of Super caps to stabilize PV system voltage.
* Use a DC to DC inverter to produce a DC charging voltage that the Leaf would like.
*Option 1) The DC/DC inverter would maintain the (Leaf required) DC voltage & Amps but drop out if Voltage or Amps could not be maintained
*Option 2) The DC/DC inverter would maintain the (Leaf required) DC voltage but vary the Amps delivered.
A) What DC charging voltage (& tolerance) does the Leaf like?
B) What DC charging Amps (& tolerance) does the Leaf like?
C) i.e. what threshold will Leaf ~400v dc port allow power in (& disallow power in)?
Ingineer
Well-known member
Here's the problem with direct DC; when your expensive solar array isn't being used to charge your car, it's going to waste. (From a conservation point of view)
Then, from the bean-counter POV you have economies of scale; a "custom" converter would have to sell a large # of units to recoup dev costs, with an already limited EV market how many will really sell? If you can make a business case, I'll built it.
The current best solution is a solar grid intertie, then standard charging gear. Yeah, it may be a few percent less efficient, but COST is the big elephant in the room here. Then, you can charge anytime, night/day/cloudy, and when you AREN'T charging your solar is still powering your house, offsetting your bill.
-Phil
Then, from the bean-counter POV you have economies of scale; a "custom" converter would have to sell a large # of units to recoup dev costs, with an already limited EV market how many will really sell? If you can make a business case, I'll built it.
The current best solution is a solar grid intertie, then standard charging gear. Yeah, it may be a few percent less efficient, but COST is the big elephant in the room here. Then, you can charge anytime, night/day/cloudy, and when you AREN'T charging your solar is still powering your house, offsetting your bill.
-Phil
DaveinOlyWA
Well-known member
Phil; any thoughts of internal losses after power is delivered in the battery; heat, etc? what percentage? even a ballpark figure would be appreciated
NREL LEAF Teardown and Detailed TestingDaveinOlyWA said:
Of the energy pumped in to the battery, you get 97% out.
DaveinOlyWA
Well-known member
drees said:
Thanks for that!!
I trust this result of 97% for overall average battery efficiency, but it is an average, because how you drive affects the battery discharge loss. As I have posted several times, the discharge loss as measured by the voltage sag under load is approximately 1% per 10 kW of delivered power. 20 kW is 2% or 400W, 30 kW is 3% or 900W, etc.drees said:
Similarly I believe the battery charging efficiency varies with charging rate. The difference may not be noticeable between L1 and L2, but it becomes important at L3 rates. The loss at a given L3 current rate also goes up with increasing SOC because the battery pack's charging impedance rises.
jpa2825
Well-known member
If you are trying to make an argument to spend the $ to get an L2 charger / 240v outlet with EVSE Upgrade, can you very roughly & broadly assume a pickup of 15% efficiency of wall to wheel (90% v. 75%)?
If so, do you then simply run your calculations to show how many less kW you pull to charge the LEAF * the $/kW your energy provider is charging you to determine how valuable this efficiency is to you?
Without knowing what my next car will be, I am finding it hard to invest $1k + wiring (or even less via EVSE Upgrade) when the 120v existing outlet in my garage is meeting my needs (but restricting my flexibility).
If so, do you then simply run your calculations to show how many less kW you pull to charge the LEAF * the $/kW your energy provider is charging you to determine how valuable this efficiency is to you?
Without knowing what my next car will be, I am finding it hard to invest $1k + wiring (or even less via EVSE Upgrade) when the 120v existing outlet in my garage is meeting my needs (but restricting my flexibility).
davewill
Well-known member
Sounds like a vicious circle. You're not using the car to it's potential because of L1, therefore, you're less likely to buy another EV next time, therefore you're reluctant to spend money on L2, therefore you're not using the car...jpa2825 said:
DaveinOlyWA
Well-known member
With 120 volt charging you cannot use more than about 75% of your range on two consecutive days. It simply charges too slowly
BrockWI
Well-known member
jpa2825 said:
This was my thought from the get go. I might have some math wrong here and correct me if I do. The problem here is it isn't just the 15% loss on the straight charging, besides that lets look at 5 days of charging for a 40 mile commute. Assuming you can run, lets say 4 miles/kwh that is 10kwh a day, so to speak. Now charging back up from level 1 you need to charge for approximately 9 hours at 300w / hour loss or 2700w lost on an overnight charge. That same charge at 6.6kw would take at max 2 hours or 600w lost. This same trip repeated 5 times a week turns in to 13.5 kwh lost for 120v charging and just 3 kwh for the 240v charging or a savings of 10kwh a week or 40kwh a month. To me that adds up pretty quick and we run closer to 80 miles a day, doubling all this.
Not to mention the ability to throw 6 kwh or 20+ miles in over lunch or dinner and keep using the leaf instead of pulling out an ice.
DaveinOlyWA
Well-known member
dglaser said:
probably closer to 90-91%. I am getting right at 90% running at 4.8 kw. i tried 5.76 for 4 days charging at least 15 kwh a day and saw no real change
Similar threads
