I recently moved to a condo in Milwaukee with a 4 stall -detached garage wired for 110 service. Because the 110 line to each of the stalls is considered ‘common’ electricity, using this to charge my car is creating an issue. Having had a 220 line and Tesla charging unit in my previous home garage, ideally, I would like to have a 220 line to the garage that is metered to my electric service. However, the cost to do that was quoted as $5,000. In absence of that, I would like to use the 110 ‘common’ electricity and pay for the kWh used to charge my car. What is the best way to measure the amount of kWh I actually use? Is there a meter (like an appliance meter) that could be plugged into the 110 line to monitor my actual usage? What does Tesla recommend in situations like this? Thanks to all for their help!
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Recommendations for how to measure kWh used to charge my model 3 in my condo garage
- Thread starter maryginnebaugh
- Start date
jrweiss98020
Tessa's Tesla
Relatively easy calculation. If you have a LR, you have a 75 kWh battery. Every 1% you charge is 0.75 kWh. With efficiency losses, warmup time, Sentry Mode drain, etc., you could round up to 1% = 1 kWh to make it exceedingly simple. If you charge from 70 to 80% every night, that would be about 300 kWh/month.
The answer depends on the precision you need. There are physical devices that can be installed on the wires to count the power usage. The rule of thumb posted here works but is not that precise. Something that has medium precision is using TeslaFi. The site tries to estimate energy loss and really receives (from the Tesla api calls) how much energy is pumped in. It's not perfect but it's an easy to use application that would give you a nice dashboard.
Here's what my last few home charges look like:
Efficiency marked here is to be taken with a grain of salt. At least you get a good estimate of kWh put in. Since electricity providers typically charge per kWh, it's a real simple multiplication to get to the price. TeslaFi actually does it if you give it your price per kWh. I input 10,8c in my configuration because that's what I pay here including tax. You can see my charge cost in the table.
NOTE: I say TeslaFi because that's the one I use. There are others like it.
Here's what my last few home charges look like:
Efficiency marked here is to be taken with a grain of salt. At least you get a good estimate of kWh put in. Since electricity providers typically charge per kWh, it's a real simple multiplication to get to the price. TeslaFi actually does it if you give it your price per kWh. I input 10,8c in my configuration because that's what I pay here including tax. You can see my charge cost in the table.
NOTE: I say TeslaFi because that's the one I use. There are others like it.
For 110V, I think you can use something like this. There are several models available.
I second the recommendation for a Ponie meter in the Amazon link - I've had one awhile to measure various appliances and it is a step up from the earlier Kill-A-Watt units.
Keep in mind that slow L1 charging does result an a somewhat stiff efficiency penalty owing to the overhead imposed by the car while charging...~200 Watts (Others here may have calculated that loss to greater accuracy than my guesstimate)
Keep in mind that slow L1 charging does result an a somewhat stiff efficiency penalty owing to the overhead imposed by the car while charging...~200 Watts (Others here may have calculated that loss to greater accuracy than my guesstimate)
hmgolds
Member
I am now in a somewhat similar situation. 7 unit condo, common garage (with 50amp service to the garage), and no cost-feasible way to bring power from my meter. So the only power in the garage is shared power billed to the association. An no easy internet access in the garage.
The other condo owners are comfortable with my measuring the power I use and reimbursing. Talking with my electrician, he suggested a submeter. The one he was familiar with is the E-Mon D-Mon (which is expensive). Lots of less expensive submeters, but he says must be UL listed. So I'm thinking of the Leviton M0340-1SW. I'd run a 240v 15 or 20amp circuit. (There is another Tesla owner who just moved in; this would allow him to do the same.) The 10-14 miles of range per hour would be adequate.
In my situation, I don't want to rely on wifi monitoring of the usage. In addition to the fact that our unit's wifi doesn't reach to the garage, there's a benefit to have a simple visible display that anyone of us can read. Makes usage very transparent.
I had tried to find an ev charger that has energy monitoring with a display, but haven't yet found one.
The other condo owners are comfortable with my measuring the power I use and reimbursing. Talking with my electrician, he suggested a submeter. The one he was familiar with is the E-Mon D-Mon (which is expensive). Lots of less expensive submeters, but he says must be UL listed. So I'm thinking of the Leviton M0340-1SW. I'd run a 240v 15 or 20amp circuit. (There is another Tesla owner who just moved in; this would allow him to do the same.) The 10-14 miles of range per hour would be adequate.
In my situation, I don't want to rely on wifi monitoring of the usage. In addition to the fact that our unit's wifi doesn't reach to the garage, there's a benefit to have a simple visible display that anyone of us can read. Makes usage very transparent.
I had tried to find an ev charger that has energy monitoring with a display, but haven't yet found one.
I have this on my house. It works well.
Emporia Smart Home Energy Monitor with 16 50A Circuit Level Sensors | Real Time Electricity Monitor/Meter | Solar/Net Metering https://www.amazon.com/dp/B08CJGPHL9/ref=cm_sw_r_apan_glt_fabc_S12QSDWD9W4775NWHD14?psc=1
Also you can buy a chargepoint charger. It gives you the stats and calculates the cost based on your electric utility rate.
ChargePoint Home Flex Electric Vehicle (EV) Charger, 16 to 50 Amp, 240V, Level 2 WiFi Enabled EVSE, UL Listed, ENERGY STAR, NEMA 14-50 Plug or Hardwired, Indoor / Outdoor, 23-foot cable https://www.amazon.com/dp/B07WXZDHGV/ref=cm_sw_r_apan_glt_fabc_V3P8EQZK1T1QG8KDSSRS
Emporia Smart Home Energy Monitor with 16 50A Circuit Level Sensors | Real Time Electricity Monitor/Meter | Solar/Net Metering https://www.amazon.com/dp/B08CJGPHL9/ref=cm_sw_r_apan_glt_fabc_S12QSDWD9W4775NWHD14?psc=1
Also you can buy a chargepoint charger. It gives you the stats and calculates the cost based on your electric utility rate.
ChargePoint Home Flex Electric Vehicle (EV) Charger, 16 to 50 Amp, 240V, Level 2 WiFi Enabled EVSE, UL Listed, ENERGY STAR, NEMA 14-50 Plug or Hardwired, Indoor / Outdoor, 23-foot cable https://www.amazon.com/dp/B07WXZDHGV/ref=cm_sw_r_apan_glt_fabc_V3P8EQZK1T1QG8KDSSRS
SageBrush
REJECT Fascism
The car will do the metering for you.
Bring up the history card in the bottom left of the screen. You can reset any of the three trip meters. If you want to pay the condo quarterly, start a trip meter (you might label Q1 for Jan - March, e.g.) End of quarter the card will show kWh/mile used by the car during motoring, and the distance traveled. The product is kWh consumed while driving for that time interval.
Divide that by 0.8 to account for vampire and charging losses. Multiply that by your condo's per kWh charge
Rinse and repeat.
Take a photo each time for documentation you supply to the condo along with the payment.
If someone says that is not exact, remind them that you are paying for everybody else's non metered usage.
Bring up the history card in the bottom left of the screen. You can reset any of the three trip meters. If you want to pay the condo quarterly, start a trip meter (you might label Q1 for Jan - March, e.g.) End of quarter the card will show kWh/mile used by the car during motoring, and the distance traveled. The product is kWh consumed while driving for that time interval.
Divide that by 0.8 to account for vampire and charging losses. Multiply that by your condo's per kWh charge
Rinse and repeat.
Take a photo each time for documentation you supply to the condo along with the payment.
If someone says that is not exact, remind them that you are paying for everybody else's non metered usage.
hmgolds
Member
2 interesting options. There is even a less expensive Emporia device that does 8 circuits. What's interesting is that we need to monitor 2 circuits, this one device would do both. Need to figure out what happens if not connected to wifi but, at first look, appears wifi required. But if it has internal memory so can access wifi from phone periodically, that would be good. Most "smart" devices will require wifi; understandable but doesn't work in this case.
hmgolds
Member
That will probably work for me as I've been here a while and people trust me. Whether that would work for the new people that just moved in, I don't know. All it takes is one person to raise a question. I might take a look to see how constant our bills are. If there isn't much variation, less likely for people to confuse normal ups and down with EV usage.
SageBrush
REJECT Fascism
Show them the odometer and the lifetime (from start of accounting) miles driven and Wh/mile.
No trust is required
The error occurs with off-site charging. That can be mostly corrected for by Tesla records if really needed, but it only matters if it matters to the OP
hmgolds
Member
Thinking about this a bit more. Not all my charging (nor even all my L2 charging) is at the condo. So wouldn't this overstate the "community" power used?
SageBrush
REJECT Fascism
hmgolds
Member
It would be time consuming to track. For example, I often charge at my son's house (10 min away), using his solar. So far, the roughly $300 submeter might be the best option. Less when you factor in the credit.
SageBrush
REJECT Fascism
Your case strikes me as a toss-up, although you have to charge at least 1500 kWh at your son just to break even.
Does OP also charge at your son's house ?
For the lion's share of people charging will be at home or at a Supercharger. The latter is very easy to track. The only obvious exception I can think of would be workplace charging, but those people would not be fighting with their condo assn.
hmgolds
Member
Not sure I understand the breakeven comment. I'm not the OP and based on the first post he/she has a similar, though completely independent situation. I'm simply looking at the simplest way for me to meter my usage at the condo so I can properly reimburse my neighbors.
afty
Member
This is pretty reasonable but I’ve found the extra usage over what the car reports to be even higher than expected — from my data you have to divide what the car reports by 0.75 to get the actual energy used to charge. And this is in an ideal climate, no preconditioning, no sentry use, etc.
Right. I wouldn't rely on what the car reports if I needed to count the energy consumption for billing purposes. The car only reports energy spent while in drive. It's great to know how much a trip consumed, but not for this purpose. You could camp in the car multiple nights and this would not be accounted for. On top of charging losses, you are missing all the energy while not in drive : camp / keep climate on, energy spent by the car while charging, energy spent in sentry mode, conditioning the cabin, which sometimes also conditions the battery, etc...
As you move your measurement closer to the meter, you'll be more precise. There are devices that monitor energy passing through the wire at the panel but you need an electrician to install that sort of thing and calibrate them. If on 120V, a device on the plug itself should be precise enough. I think that apps like TeslaFi that report the amount of energy put into the car would be close enough. I'm sure there's a little discrepancy from reality but by counting energy that goes in, you're accounting for all scenarios at least.
EDIT: In fact, by looking at the trip meter you could be paying your condo owner for energy that you put in the car at a supercharger. IT makes no sense to me to count it this way...
As you move your measurement closer to the meter, you'll be more precise. There are devices that monitor energy passing through the wire at the panel but you need an electrician to install that sort of thing and calibrate them. If on 120V, a device on the plug itself should be precise enough. I think that apps like TeslaFi that report the amount of energy put into the car would be close enough. I'm sure there's a little discrepancy from reality but by counting energy that goes in, you're accounting for all scenarios at least.
EDIT: In fact, by looking at the trip meter you could be paying your condo owner for energy that you put in the car at a supercharger. IT makes no sense to me to count it this way...
SageBrush
REJECT Fascism
Since rated miles (RM) is energy * a_constant,
OP can keep a log of RM before and after each at home charge
OP can keep a log of RM before and after each at home charge
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