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Discussion Starter #1 (Edited)
All right guys, new thread on a subject I started a while ago. Here is MY real world charging data compiled from MyChevrolet app for each charging option.

First the vehicles own guestimate of charging times on the dash and the MyChevrolet app projections for the different charging options along with the real world results.
The 240V testing was all done with charging temperature in the low 80’s, and the 120V charge tests started in the low 80’s and dipped into the high 50’s overnight temperatures during the charge.
Line voltage was verified at 120V and 240V.

These are my numbers for these charging sessions under these conditions! I would expect them to vary depending on ambient conditions… anyone know what are considered “optimal” charging conditions for the Volt?

Charge rate . . . . . . . .Guestimate on dash . . . . . . . . . App projection . . . . . . . . . .Real world results
120V 8 amp . . . . . . . . . . . . .20.0 . . . . . . . . . . . . . . . . . .20.5 . . . . . . . . . . . . . . .17.5/18.5*
120V 12 amp . . . . . . . . . . . .13.0 . . . . . . . . . . . . . . . . . .13.75 . . . . . . . . . . . . . . 11.5/12*
240V 12 amp . . . . . . . . . . . . N/A . . . . . . . . . . . . . . . . . . .6.0 . . . . . . . . . . . . . . . .5.5
240V 15 amp . . . . . . . . . . . . 4.5 . . . . . . . . . . . . . . . . . . . 4.5 . . . . . . . . . . . . . . . .4.5

The real world results for the 120V charge rates have an * because that is the time to reach 100%, and the time to reach “fully charged”. At 8 amps it looks like it takes a full hour past 100% for battery cell balancing and at 120V 12 amps it takes a half an hour for the cell balancing.

So, with 8 amp 120V charging you gain 3 miles of EPA range per hour of charging up to 100% and then spend another hour on cell balancing where you may gain another mile on the guess-o-meter.

With 12 amp 120V charging you gain 4.6 miles of EPA range per hour of charging up to 100% and then spend another half hour on cell balancing where you may gain another mile on the guess-o-meter.

With 12 amp 240V charging for the bulk of the charging (first 5 hours) you gain an average of 10 miles of EPA rated range per hour of charging, and another 3 miles in the last half hour.

With 15 amp 240V charging for the bulk of the charging (first 4 hours) you gain an average of 12.1 miles of EPA rated range per hour of charging, and another 4.8 miles in the last half hour.

Other than the end of charge balancing there is no “slow down” to the charge rate with 120V charging… there is a slight slow down with the two 240V charging options so I will give the hour by hour results:

12amp 240V:

1st hour charging, battery level 20%. Gain of 20% and EPA rated range gain of 10.6 miles.

2nd hour charging, battery level 38%. Gain of 18% and EPA rated range gain of 9.5 miles.

3rd hour charging, battery level 57%. Gain of 19% and EPA rated range gain of 10.1 miles.

4th hour charging, battery level 75%. Gain of 18% and EPA rated range gain of 9.5 miles.

5th hour charging, battery level 94%. Gain of 19% and EPA rated range gain of 10.1 miles.

Last half hour charging, battery level 100%. Gain of 6% and EPA rated range gain of 3.2 miles.


For the 15 amp 240V the situation is very similar, just a bit faster :)

1st hour charging, battery level 24%. Gain of 24% and EPA rated range gain of 12.7 miles.

2nd hour charging, battery level 47%. Gain of 23% and EPA rated range gain of 12.2 miles.

3rd hour charging, battery level 69%. Gain of 22% and EPA rated range gain of 11.7 miles.

4th hour charging, battery level 91%. Gain of 22% and EPA rated range gain of 11.7 miles.

Last half hour charging, battery level 100%. Gain of 9% and EPA rated range gain of 4.8 miles.


Just for giggles I compared the power available from the grid to what made it into the battery over the full charge with the following results… in another post I was told this is not the efficiency of the charging system… but if you do the division my numbers are very close to what GM considers the efficiency of it’s charging system.

An 8 amp 120V draw from the grid is 960 watts. Results into the battery is 14 kWh/17.5 = 800 watts.

A 12 amp 120V draw from the grid is 1,440 watts. Results into the battery is 14 kWh/11.5 = 1,217 watts.

A 12 amp 240V draw from the grid is 2,880 watts. Results into the battery is 14 kWh/5.5 = 2,545 watts.

A 15 amp 240V draw from the grid is 3,600 watts. Results into the battery is 14 kWh/4.5 = 3,111 watts.

Once again, these are my results with my car on my stock EVSE and my clipper creek LCS20 under my charging conditions… your results may vary :D

Keith
 

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Excellent work! It agrees with my own experience. I used my exterior 120V/15A circuit for the first month I owned my 2017 Volt, and then installed a dedicated 240V/30A circuit for a GE WattStation. The time to charge on both circuits agree with yours. At work, I have access to a 208V/16A EV station which takes around 6 hours to charge the Volt (it's 55 miles from home, so I'm dead empty when I arrive).
 

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Lots of data, but no real surprises. In the past, we would argue about total power consumed during charging:

1. Which mode takes the fewest kwh?
2. Can I save money charging at 8A instead of 12A on 120V?
3. Can I save enough kwh to justify setting up 240V charging?

I believe the consensus was the 240V was the most efficient, but if you didn't mind the slower charge rate, the extra expense to install a 240V system was not worth it. But I don't remember any definitive data on 8A vs 12A.

If I go out in the morning for a little local shopping on my day off, and only consume a kwh or 2, get home, and plan to be drinking the rest of the day (car won't be used for over 24 hours), should I charge at 8A or 12A?
 

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For your reference, I have attached an image (and higher resolution pdf file) of the Gen 2 Volt on-board charger (OBC) charging efficiency charts at 120 and 240 VAC input, at various initial battery-voltages. This is part of SAE paper 2016-01-1229, which describes in-detail the design and operation of the OBC. The instantaneous charging efficiency varies with initial voltage of the battery, charge % complete, and input voltage, so you can't make a broad-brush efficiency determination from a single point of measurement for input vs output watts.

Gen 2 Volt on-board charger efficiency chart.jpg

View attachment OBC charger efficiency.pdf
 

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<snip>

If I go out in the morning for a little local shopping on my day off, and only consume a kwh or 2, get home, and plan to be drinking the rest of the day (car won't be used for over 24 hours), should I charge at 8A or 12A?
LOL That depends on whether or not you are sipping Laphroaig.:cool:;) 8A or 12A wouldn't matter in that case - a matter of a fraction of a penny:).
 

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In theory higher charge currents will lead to higher inefficiencies as more heat is produced (power lost to heat is a function of I^2*R). Higher Voltages mean higher efficiency, since a smaller percentage of your total power delivered to the load is lost as heat. So high voltage and low current is efficient.

However, there are other factors like overhead to consider, like overhead from running any cooling pumps and such. So based on the numbers provided above in this thread it looks like 240V 12A is the most efficient, but all are within 5% of each other (83 to 88%). This is going to vary on ambient temperature, etc.
 

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For your reference, I have attached an image (and higher resolution pdf file) of the Gen 2 Volt on-board charger (OBC) charging efficiency charts at 120 and 240 VAC input, at various initial battery-voltages. This is part of SAE paper 2016-01-1229, which describes in-detail the design and operation of the OBC...
Seems like the 240v OBC is maybe 1.5% to 4% better than [email protected] I assume some additional 240v advantages in the wiring, and maybe in the battery TMS too, since the charging time is shorter. So maybe 4% better overall?

I'm seeing a range of 4 hours 15-25 minutes at [email protected]; averaging 15.8kwh on myvolt.com; so figure 12%-13% charging overhead which should increase in the heat of the summer.

Fourdoor says 4.5 hours for [email protected]
Fourdoor says 11.5 hours for [email protected]; which is probably more like 16.4kwh (mostly a guess)

The 106mpge spec says a full charge should average 16.8kwh to drive 53 miles.
 
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