Tracking efficiency

[Billyt1963]

So I have tracked the efficiency of my gas vehicles for as long as I have owned one (1987). I am trying to figure out the best way to do that on an EV. I realize the vehicle will do that for you, but many of my gas vehicles would do that and that were overly optimistic. I guess as long as I charge to the same level every time, I could just divide the miles driven by the amount of every charge. Anyone have any thoughts on how to do this?

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[zefram47]

Use ElectraFi and you don't need to make it complicated. It tracks each drive as well as each charge. You can track efficiency for multiple tire sets, temperature conditions, and mark road trips by datetime to easily see stats over the trip. Following the directions to calibrate the efficiency with charging, I've found it to be pretty close to the in-vehicle trip data.

https://www.electrafi.com/signupRivian.php?referred=zefram47

 

[Billyt1963]

Thanks, I will check it out.

 

[COdogman]

I track mine by having 4 cars following me at each corner of my truck, counting the revolutions of each tire, reporting to my employee who lives in the backseat via 2 way radio. She watches the battery and does the math. So far it’s working great and very convenient for all…??

 

[Marchin_MTB]

If your at home charger reports energy output, you can use that and combine it with the odometer.

personally, I use the trucks estimate. I keep one trip without resetting for lifetime efficiency. I reset the other one every 100-200 miles, or over the course of a road trip, to track how things change.

 

[usulio]

The complicating factor is electricity lost while sitting still, a.k.a. phantom drain. I would not include that in the efficiency because it would make the vehicle look less efficient for a road trip (continuous driving) than it really is. OTOH if you want to track total energy consumption and cost of ownership then you should include it.

 

[Riviot]

I track mine by having 4 cars following me at each corner of my truck, counting the revolutions of each tire, reporting to my employee who lives in the backseat via 2 way radio. She watches the battery and does the math. So far it’s working great and very convenient for all…??

Don't listen to this bluffin fool, OP, she was fired months ago.

 

[Robin]

I track mine by having 4 cars following me at each corner of my truck, counting the revolutions of each tire, reporting to my employee who lives in the backseat via 2 way radio. She watches the battery and does the math. So far it’s working great and very convenient for all…??

?????

 

[White Shadow]

I thought the phantom drain issue was solved, no? I mean, I know some juice will always be used, but for the most part it's not an issue anymore, right?

 

[Herb]

I thought the phantom drain issue was solved, no? I mean, I know some juice will always be used, but for the most part it's not an issue anymore, right?

Nope, not solved. To be fair, this might be more complicated than meets the eye. All batteries will read lower at lower temperatures as chemical reactions slow with decreasing temperatures. After parking, battery temperatures drop which probably contributes to some reported losses. Logic tells me that some of these perceived losses will reverse once the battery warms again, but never go back on the meter. Nevertheless, there also seem to be significant actual losses that remain largely unexplained, or at least there are a lot of theories.

 

[Herb]

So I have tracked the efficiency of my gas vehicles for as long as I have owned one (1987). I am trying to figure out the best way to do that on an EV. I realize the vehicle will do that for you, but many of my gas vehicles would do that and that were overly optimistic. I guess as long as I charge to the same level every time, I could just divide the miles driven by the amount of every charge. Anyone have any thoughts on how to do this?

There are two ways to look at this: driving efficiency and overall efficiency. Overall efficiency should include phantom drain and charging losses. These can add up quickly depending on your use case. The EPA recorded it takes about 162kWh to charge a completely depleted 141kWh battery. I suspect part of this are inverter losses but most of this energy goes into the battery as it heats during charging. This is for a DM Max pack, but I think the EPA did this for every configuration: display_file.jsp (epa.gov). I wouldn't be surprised if overall efficiency is 15% worse than driving efficiency, but that depends on your use case, temperature, etc. Anyways, much more complicated and tracking ICE efficiency...

 

[Billyt1963]

There are two ways to look at this: driving efficiency and overall efficiency. Overall efficiency should include phantom drain and charging losses. These can add up quickly depending on your use case. The EPA recorded it takes about 162kWh to charge a completely depleted 141kWh battery. I suspect part of this are inverter losses but most of this energy goes into the battery as it heats during charging. This is for a DM Max pack, but I think the EPA did this for every configuration: display_file.jsp (epa.gov). I wouldn't be surprised if overall efficiency is 15% worse than driving efficiency, but that depends on your use case, temperature, etc. Anyways, much more complicated and tracking ICE efficiency...

Thanks for the detailed explanation. I will probably count all losses/uses of the energy. From the looks of it, I will have a while to figure it out.

 

[whyasky]

Use ElectraFi and you don't need to make it complicated. It tracks each drive as well as each charge. You can track efficiency for multiple tire sets, temperature conditions, and mark road trips by datetime to easily see stats over the trip. Following the directions to calibrate the efficiency with charging, I've found it to be pretty close to the in-vehicle trip data.

https://www.electrafi.com/signupRivian.php?referred=zefram47

Does it track overall efficiency including losses from idle, vampire drain, etc? It seems to show these things independently but I can't see anywhere that it is shows the entire picture for the truck. Seems an obvious miss - unless I'm the one missing it.

 

[DeafPug]

For my Model 3, I track the actual electricity consumed, not what the trip meter says was consume. The trip meter doesn't include charging inefficiencies or vampire drain. These numbers are NOT the same.

Miles: 103,487
Trip kWh: 27,717
Actual kWh: 33,254 (Home + Superchargers = 26,185 + 7,069)

My trip meter underreported the actual electricity consumed by 17% - the discrepancy is more in the higher in the winter since more energy is consumed for cabin pre-heat

I have a system from theenergydetective.com mounted in my main breaker panel to monitor the actual kWh that passes through the home charging station. You can also wire an electricity monitor like https://www.amazon.com/DROK-80-300V...ay0fbt_hardlines_d_sccl_1/146-3796449-8455208 in-line with the EVSE to monitor power usage. You would obviously need to mount this in some form of electric box.

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