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Is there a way to get the power consumption of the wall charger for each c?
- Thread starter neutronjeff
- Start date
srs5694
Active Member
You can extract data from the car using TeslaFi, various apps, or the Tesla API (if you care to write your own script). This information will not directly measure the power used by the EVSE, though, just the power consumed by the car. There will be some small losses between the two and perhaps other reasons for discrepancies. TeslaFi, at least, records both power stored in the battery and power taken in by the car, which enables it to calculate a charging efficiency. On rare occasions, this is over 100%, which is theoretically impossible, so clearly there's some measurement error. I seem to recall hearing that this is because the API provides a sum total for charge added to the battery (in kWh) but only minute-by-minute recording of the instantaneous power use (in kW), and TeslaFi sums the latter over time. If this is correct, then any API-based tool will be of limited accuracy in total power drawn from the wall.
Beyond that, you'd need to add or replace hardware. A simple electric meter (like the kind your house has to measure power used for billing by the utility) in-line with the EVSE will do the trick, but if you want per-charge-session data, you'd need to check it manually every time you unplug. Maybe there are WiFi-enabled networked meters that will help with this, but if so, I don't have references to them.
A similar option would be to replace the Tesla Wall Connector with a third-party EVSE with networking capabilities, like a JuiceBox, ChargePoint Home, or OpenEVSE. These devices can do exactly what you want, although you'd need to use Tesla's J1772 adapter with them. It might be possible to take components from one of these and add it to Tesla's Wall Connector to add WiFi capabilities, but I'm far from certain of that; certainly I've never heard of it being done.
There are also whole-house electricity monitoring tools available. I'm not very familiar with these products, but my understanding is that some of them can learn to identify specific devices because of their patterns of use. I'd expect an EVSE would be easy to identify because it draws so much power; however, there might be some slop (missed use) if the car draws less than its usual amount of current -- say if you turn on the cabin heat or AC shortly before you leave.
Beyond that, you'd need to add or replace hardware. A simple electric meter (like the kind your house has to measure power used for billing by the utility) in-line with the EVSE will do the trick, but if you want per-charge-session data, you'd need to check it manually every time you unplug. Maybe there are WiFi-enabled networked meters that will help with this, but if so, I don't have references to them.
A similar option would be to replace the Tesla Wall Connector with a third-party EVSE with networking capabilities, like a JuiceBox, ChargePoint Home, or OpenEVSE. These devices can do exactly what you want, although you'd need to use Tesla's J1772 adapter with them. It might be possible to take components from one of these and add it to Tesla's Wall Connector to add WiFi capabilities, but I'm far from certain of that; certainly I've never heard of it being done.
There are also whole-house electricity monitoring tools available. I'm not very familiar with these products, but my understanding is that some of them can learn to identify specific devices because of their patterns of use. I'd expect an EVSE would be easy to identify because it draws so much power; however, there might be some slop (missed use) if the car draws less than its usual amount of current -- say if you turn on the cabin heat or AC shortly before you leave.
kkillebrew
Banned
For what it is worth I was curious about actual draw when I installed my HPWC so I tested it on one of the hot lines with a clamp meter on a 48 amp charge before buttoning everything up at the breaker box. I don't remember the exact number but it was 48 amps and some change and voltage would peak at 247 causing the car to regulate the amps down to keep a constant 12KW draw/charge. Not sure where that regulation occurs in the Wall charger or the car charger. The wall charger is not really a charger anyway, it's more an intelligent regulator, and all the DC conversion happens in the car with Level 2, so that is the most likely place for inefficiency. All in all pretty efficient considering it all goes through the Wall charger, the car charger, and then to the batteries. If you are worried about loss the length and AWG size of the run will have the greatest impact.
If you truly want the actual power out of the wall, you want to use a current clamp on the AC input (one leg should be fine, since it's symmetrical).
There's a bunch of examples of these current transformer examples. Here's one:
ATM90E32 Power Sensor
There's a bunch of examples of these current transformer examples. Here's one:
ATM90E32 Power Sensor
boriszima
Member
Some buy something like this to monitor their electricity use at home. There are also cheaper alternatives. I don’t have it bought thought to see what sucks juice at my place.
Sense Energy Monitor - Track Electricity
https://www.amazon.com/dp/B075K6PHJ9/ref=cm_sw_r_cp_api_i_swB6Db8ZYPRKK
Sense Energy Monitor - Track Electricity
https://www.amazon.com/dp/B075K6PHJ9/ref=cm_sw_r_cp_api_i_swB6Db8ZYPRKK
This looks interesting, but I've never used it myself....
https://smile.amazon.com/Emporia-En...r_1_14?keywords=efergy&qid=1575600661&sr=8-14
There's also this... which I have used, but is not web/app enabled, and tracks only one circuit...
https://smile.amazon.com/Efergy-4-0...=sr_1_3?keywords=efergy&qid=1575600762&sr=8-3
Either of these requires that you get in your electrical panel or subpanel to install it. Not very hard or dangerous, if you have a clue.
https://smile.amazon.com/Emporia-En...r_1_14?keywords=efergy&qid=1575600661&sr=8-14
There's also this... which I have used, but is not web/app enabled, and tracks only one circuit...
https://smile.amazon.com/Efergy-4-0...=sr_1_3?keywords=efergy&qid=1575600762&sr=8-3
Either of these requires that you get in your electrical panel or subpanel to install it. Not very hard or dangerous, if you have a clue.
The "wall unit" only communicates with the car the number of amps that are available for charge (so far as I understand), and it also listens for start/stop commands. It cuts the power to the cable when not charging for safety reasons.
The "charger" specifically, which does AC -> DC, is located inside of the car. The information is available to the car, but it does not appear to be accumulated anywhere.
The internet services like TeslaFi work by constantly requesting the car's status via API, very much a "brute force" type of solution.
There are three different energy readings of importance. The car's consumption is specified in terms of Wh/m. These Wh are the energy from the battery to the motor (and potentially other equipment running in the car). Then there is the energy into the battery when charging which I believe is what the car displays during a charging session. Finally there is the energy provided to the car which factors in the losses in the AD/DC converter, cables, etc. The car does not track this as far as I am aware. Many EVSE do.
There is an openEVSE that will charge a Tesla on a 50 amp circuit which provides various information about the energy used. It's the same cost as the Tesla HPWC or a bit less if you buy the kit. The last time I wrote the guy behind it he would sell you a cable with a Tesla connector to gain the advantage of not needing to use your J1772 adapter.
I'm not at all convinced that those apps are constantly requesting status...
As an experiment, I turned off my phone completely, then recharged my 3 completely and disconnected the HPWC. Finally I turned my phone back on and opened "Dashboard For Tesla" and went to its charging screen. It tells me my "Most Recent Charge" is 12.5kwh, which is what I would have needed...It is notably different than my mid-day charge of 24.5kwh (which I had checked before turning off the phone).
So as long as you check it before you start your next charge session, you can manually record it.
Another option I hadn't seen yesterday is this... for only $50.... two minor downsides are
1) that it's really intended as a whole-house meter, and the two supplied sensors are a little imprecise if you use them only for an HPWC.
2) it just assumes 240V(actually 120V per line), so the real power isn't being measured here, either.
You can solve 1) by buying the vue unit direct from emporia energy, and adding two $7.49 sensors that read only up to 50 amps. The price is the same as amazon, but amazon doesn't seem to sell individual sensors.
https://smile.amazon.com/Emporia-En...coding=UTF8&psc=1&refRID=X1XB056TWZ15Y8ZE7WE1
Thanks... I think this is the line you want to look at for the most recent charge event....
"charge_energy_added": 18.77,
Yes, if you polled that same request(frequently) you could probably get to about the same answer using the charge voltage and current..... but why not let the car do it for you...
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