[bobr33543]

We don't have 110 or 220 volts in the US. It's 120 or 240 at homes. 208 volts is common for commercial power in the US but likely uncommon for single family homes.

In reality it is 117 volts AC RMS in the US. But let's not nitpick.

 

[oscarwittlief]

I measured the charging efficiency on my Bolt and got 80% efficiency. At that level, you should have gotten 36KW of charge into your batteries if you used 45KW line energy. So you aren't far off. I don't know what technology GM uses for their chargers, but if it is a series regulator, the numbers you read are probably accurate. In order to get more efficient, you would need what is called a switching regulator and that is more expensive to manufacture. So it doesn't take a rocket scientist to figure out why GM didn't go that way. They aren't paying for your electrical power. I don't like government interference, but that is what is needed to force the EV manufacturers to use more efficient chargers. After all, our government did that to force car manufacturers to optimize miles per gallon of gasoline.
Dave W

I havent looked into it but the charger in the car has to be some form of a switching step up power supply, because it can charge from 120VAC or 240VAC and the battery is 380 to 400VDC

so it has to be some form of PWM pumping up inductors or an LC filter circuit

and here is the catch: most meter circuits assume a pure sinewave and measure the average voltage and current. But when the load is being pulsed or chopped you need an RMS meter to get an accurate reading

RMS meters cost 3 to 4 times as much, like a Fluke 87 compared to a Fluke 83.

Most meters are not true RMS.

 

[Pvillerob]

Pvillerob left us.

Nope, still here. Some of ya just got off into the weeds....😄

 

[elasticmedia]

I've recently been monitoring our power usage by looking at PG&E'S readout of our usage data. I can clearly see when my car is charging, and how much power it used. I was surprised to see that, while the car took on 30-35KW, it took 45KW to do so! Really? 10 KW in charging inefficiencies? Seems like a lot!

How do you measure exact energy usage from PGE to calculate this? Do you use the meter or do you log onto you account online?

 

[Pvillerob]

I was using my energy usage numbers as reported by PG&E via my online portal.

 

[quoqanq]

Nope, still here. Some of ya just got off into the weeds....😄

Much to the chagrin of my wife, I love weeds.

 

[ClarDold]

I've recently been monitoring our power usage by looking at PG&E'S readout of our usage data. I can clearly see when my car is charging, and how much power it used. I was surprised to see that, while the car took on 30-35KW, it took 45KW to do so! Really? 10 KW in charging inefficiencies? Seems like a lot!

I have a few different ways to look at my energy usage while charging the Bolt.
PG&E offers a graph of blocks, and if I click on a block, I can see the draw for that hour, 6.07 kWh, for example.
That's for the whole house, in my case, which runs about 400 watts doing nothing, but might have some other usage from time to time.
I have a Tesla Powerwall,which should show house draw in agreement with PG&E, 6.0 kW.
I have a JuiceBox, which lets me see the energy being supplied to the Bolt. 5.6 kW That's the only worthwhile measurement.
5.6 / 6.04 =93% That looks like a 7% loss, but it's not. It isn't going to the car at all, except for the drop between the meter and the EVSE. I have measured that, but I don't have it handy. The rest of that loss is idle draw in your house. You could look at the other nearby PG&E blocks to guess what that might be.

I also have an OBD reader. That could give me the starting and ending levels of kWh in the battery in ABRP.
I can also use the OBD and CarScanner to view the AC draw and the DC provided to the battery during a charge.
The Carscan is from some other date. It shows AC of 24.6*240 = 5904, and DC of 15.5 * 347.5 = 5386.25
5386.25 / 5904 = 91%.

 

[jefro]

I'd put a better meter on the car evse.

However if the electric company said you are using more then maybe I'd not complain. Maybe you are getting power at a lower rate.

 

[ClarDold]

I have a few different ways to look at my energy usage while charging the Bolt.
PG&E offers a graph of blocks, and if I click on a block, I can see the draw for that hour, 6.07 kWh, for example.
That's for the whole house, in my case, which runs about 400 watts doing nothing, but might have some other usage from time to time.
I have a Tesla Powerwall,which should show house draw in agreement with PG&E, 6.0 kW.
I have a JuiceBox, which lets me see the energy being supplied to the Bolt. 5.6 kW That's the only worthwhile measurement.
5.6 / 6.04 =93% That looks like a 7% loss, but it's not. It isn't going to the car at all, except for the drop between the meter and the EVSE. I have measured that, but I don't have it handy. The rest of that loss is idle draw in your house. You could look at the other nearby PG&E blocks to guess what that might be.

I also have an OBD reader. That could give me the starting and ending levels of kWh in the battery in ABRP.
I can also use the OBD and CarScanner to view the AC draw and the DC provided to the battery during a charge.
The Carscan is from some other date. It shows AC of 24.6*240 = 5904, and DC of 15.5 * 347.5 = 5386.25
5386.25 / 5904 = 91%.
View attachment 66831

View attachment 66828
View attachment 66827 View attachment 66830
View attachment 66829

While charging the Bolt, which lets me see onboard charger AC volts with an OBD and CarScanner:
PG&E Smart Meter 243.8 volts, ([23.4 amps], 5.7 kW)
JuiceBox 238 volts, 23.4 amps, 5.57 kW
OBD CarScanner 236 AC volts, 23.6 AC amps, 5.57 kW
OBD CarScanner 391 DC volts, 13.6 DC amps, 5.32 kW

Circuit loss from house to charging outlet (243.8 - 238) * 23.4 = 135.72 watts
From Juicebox to Bolt charger (238 - 236) * 23.4 = 46.8 watts
DC charger ratio to house input AC 5.32/5.7 = .9333

This is on a 30 amp dryer circuit, with 80 feet of #10 AWG.

This was after the car had been charging for a few hours, so the wires were heated. The first few minutes might have lower loss.

 

[drwyatt]

I've recently been monitoring our power usage by looking at PG&E'S readout of our usage data. I can clearly see when my car is charging, and how much power it used. I was surprised to see that, while the car took on 30-35KW, it took 45KW to do so! Really? 10 KW in charging inefficiencies? Seems like a lot!

You can buy a power monitoring device at Amazon to measure all parameters of your charge. I have used the 120 vac/8a with the charge that came with the Bolt. It keeps my car charged to my needs. A typical recharge is from 150 to 250. That typically takes about 18KWH charge. Local off peak power cost .14KWH. The charge would cost about $2.80 for the 100 miles traveled. My old gasser would have used about 3.6 gal at local gas cost about $14.00.
Also any time you convert energy use from 1 type to another there is a cost of the conversion. Anything under about 20% is good. My advice is in anything you do kiss, keep it simple. Dave

 

[jefro]

I did buy an emporium charge meter for panel with maybe 12 or more amp probes. Some you simply put on one leg of 240V and use double in app.
Seemed kind of less helpful after I found that the power company reports power every 15 minute slices. They also break it down by house use as in how much the smart meter thinks the car is charging. It was very close to what I was calculating on dash and from web meter readings. Do I need to get closer to actual cost. No, the EPA website let me calculate my use when I originally wanted to go electric. That was the worst only due to my much lower time of use. EPA is or was $500 a year. I am willing to bet it's under $300 true cost with all factors in..

Oh need to go to energystar to see how much your evse is costing sitting there too. Some are pretty high 24/7

 

[drwyatt]

I don’t see significant cost when sitting. Recommendations are if hot or cold leave the car plugged in. Your battery is heated and cooled below about 40’ and above 90’. I live in winter in Arizona with cold winter mornings and hot later spring and summer days. I usually leave it plugged in. My metering shows the charge cost to be about 30% less than gas cost would be with my previous 2018 Honda CRV, it was a pretty efficient gasser. I have finally after 4 months of shopping got a reasonable good auto insurance that is only 120% in cost on my old car. Initially paid almost 200% over previous gasser car cost. Every site was almost identical in cost . Insurance companies really try to screw you. Probably because of all the idiot Tesla drivers who crash and burn regularly. They need to govern down the really high performance of many EV’S. Most drivers don’t realize they are driving a car with racing performance. Dave

 

[usedBolt]

In reality it is 117 volts AC RMS in the US. But let's not nitpick.

According to my APC UPS monitoring software, the current input voltage is 121.0 VAC.

 

[jmcbrew]

According to my APC UPS monitoring software, the current input voltage is 121.0 VAC.

It all depends on where you live and the demand on the grid… as well as the wiring to the device being powered. At the moment, I have 251.0 volts at my EVSE, so about 125.5 volts on each leg. In the middle of the day, that’ll probably be down to around 220/110V.

 

[usedBolt]

It all depends on where you live and the demand on the grid… as well as the wiring to the device being powered. At the moment, I have 251.0 volts at my EVSE, so about 125.5 volts on each leg. In the middle of the day, that’ll probably be down to around 220/110V.

True, but I was triggered by the 117V comment. Yes, it specified RMS, which might be lower than what the UPS or other powerline monitoring devices report. Still, my UPS only reports voltage below 120 when the grid is heavily stressed - like late in a very hot afternoon. 117 would be near-brownout for this area. Normal input voltages are between 121 and 125, typically 122-123.

If I check voltage during the overnight when the EVSE is running, it will usually be relatively low - 119 is pretty common. There aren't a lot of EVs parked and plugged in around the neighborhood, so that's not doing it; more likely, there's just less generation on line at that time of night. In the summer, of course, general a/c demand can still be substantial with outside temps not dropping below 80F until well after midnight. I have the house thermostats set below normal overnight to do some pre-cooling using the EV charging discount.

There's a micro-event some time in late morning, most days, that other equipment never notices (and lights if on at the time don't blink) but the UPS interprets as an outage going to battery briefly (usually for just a couple of seconds). I'm guessing some kind of switching transient. I'd associate it with the solar panels in some way, since it usually happens within an hour or 2 of them reaching peak production, except that it's been happening nearly forever. An actual light blink in the early morning (just before dawn) is also pretty common. No biggie; consider it a grid-triggered self-test. Oh, and the APC UPS (on the tower computer) does it but the Cyberpower (for the internet gateway) does not. So whatever it is, isn't big. And it's definitely not related to EV charging.

This is in SMUD, not PG&E. Not, strictly, part of the CalISO system.

 

[jmcbrew]

True, but I was triggered by the 117V comment. Yes, it specified RMS, which might be lower than what the UPS or other powerline monitoring devices report. Still, my UPS only reports voltage below 120 when the grid is heavily stressed - like late in a very hot afternoon. 117 would be near-brownout for this area. Normal input voltages are between 121 and 125, typically 122-123.

If I check voltage during the overnight when the EVSE is running, it will usually be relatively low - 119 is pretty common. There aren't a lot of EVs parked and plugged in around the neighborhood, so that's not doing it; more likely, there's just less generation on line at that time of night. In the summer, of course, general a/c demand can still be substantial with outside temps not dropping below 80F until well after midnight. I have the house thermostats set below normal overnight to do some pre-cooling using the EV charging discount.

There's a micro-event some time in late morning, most days, that other equipment never notices (and lights if on at the time don't blink) but the UPS interprets as an outage going to battery briefly (usually for just a couple of seconds). I'm guessing some kind of switching transient. I'd associate it with the solar panels in some way, since it usually happens within an hour or 2 of them reaching peak production, except that it's been happening nearly forever. An actual light blink in the early morning (just before dawn) is also pretty common. No biggie; consider it a grid-triggered self-test. Oh, and the APC UPS (on the tower computer) does it but the Cyberpower (for the internet gateway) does not. So whatever it is, isn't big. And it's definitely not related to EV charging.

This is in SMUD, not PG&E. Not, strictly, part of the CalISO system.

I wouldn’t consider 117 bolts to be a brownout. I have a few UPS devices, mostly APC. The one in my living room will trigger once or twice a day. I don’t know whether it is voltage or frequency related. That reminds me… it needs a new battery. As I type this, voltage at my breaker box is 234, which means each leg is 117. Pretty normal for the middle of the day. There’s even a brand new transformer out on the pole.

 

[usedBolt]

I wouldn’t consider 117 bolts to be a brownout. I have a few UPS devices, mostly APC. The one in my living room will trigger once or twice a day. I don’t know whether it is voltage or frequency related. That reminds me… it needs a new battery. As I type this, voltage at my breaker box is 234, which means each leg is 117. Pretty normal for the middle of the day. There’s even a brand new transformer out on the pole.

View attachment 67230

Yeah, "brownout" is a bit of exaggeration. But it's about as low as I've ever seen it before an outage. 121-122 is normal.

 

[jefro]

NEC is either 5% or 10% so 120 x .80