Poor Level 1 charging efficiency

[Cybergirl]

Off-road adventure in an all electric vehicle can be risky. Having a portable fossil fuel generator or solar generator can ease the anxiety of running out of battery miles from the nearest charging station. Understanding what constitutes a viable range extending power source is important, and the question of charging efficiency feeds into that understanding.

Today, I attempted to charge my Cybertruck from a 120V 15A receptacle in my garage using Gen 2 mobile connector (Level 1 charging). The battery was at 56% SOC and the charge limit was set to 60%. At the start, the 'time remaining' display was 3 hrs and 5 min which looked encouraging. I plugged the mobile connector into a Kilowatt meter to measure the power flowing into the truck. It read 1435W. I turned off all possible parasitic loads. The ambient air temperature was 64F, and the battery temperature was 18.75 - 22.25 deg C. The HV service display showed everything was working.

After the estimated 3 hrs and 5 min, the 'time remaining' still read 1 hr 10 min and the battery state of charge was only 58%. The Kilowatt meter recorded that 4.42 kWh of grid energy had been fed to the truck. The battery temperature had risen to 21.25-25.75 deg C.

I continued charging until the 60% charging limit was finally reached after 5 hrs and 15 min with 5 kWh of accumulated battery energy. The Kilowatt meter measured 7.57 kWh from the grid, so the charging efficiency was approximately 66%.

Frankly, I didn't expect such poor efficiency from Level 1 charging using the mobile connector, and it made me question the economic practicality of Level 1 charging as a routine practice. I'm also having doubts about using solar panels to augment the truck's battery charge to achieve more driving range. Better to use solar panels to power things that would otherwise drain energy from the truck's battery (refrigerator, A/C, electric appliances, etc.)

At higher charging power the situation is not so dire. I think my dual fuel generator will be a good fallback power source when extra driving range is needed.

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[Outdoors]

Off-road adventure in an all electric vehicle can be risky. Having a portable fossil fuel generator or solar generator can ease the anxiety of running out of battery miles from the nearest charging station. Understanding what constitutes a viable range extending power source is important, and the question of charging efficiency feeds into that understanding.

Today, I attempted to charge my Cybertruck from a 120V 15A receptacle in my garage using Gen 2 mobile connector (Level 1 charging). The battery was at 56% SOC and the charge limit was set to 60%. At the start, the 'time remaining' display was 3 hrs and 5 min which looked encouraging. I plugged the mobile connector into a Kilowatt meter to measure the power flowing into the truck. It read 1435W. I turned off all possible parasitic loads. The ambient air temperature was 64F, and the battery temperature was 18.75 - 22.25 deg C. The HV service display showed everything was working.

Better to use solar panels to power things that would otherwise drain energy from the truck's battery (refrigerator, A/C, electric appliances, etc.)

I think I told everyone that before. Buy an larger ECO flow and use the crap out of that, and it works great with the solar. Save the juice of the truck for movement.

I also don't charge in service mode. Not saying you were, but might be different. I also use level 1 here and there. Don't have your experience less generator.

 

[GuyV]

Off-road adventure in an all electric vehicle can be risky. Having a portable fossil fuel generator or solar generator can ease the anxiety of running out of battery miles from the nearest charging station. Understanding what constitutes a viable range extending power source is important, and the question of charging efficiency feeds into that understanding.

Today, I attempted to charge my Cybertruck from a 120V 15A receptacle in my garage using Gen 2 mobile connector (Level 1 charging). The battery was at 56% SOC and the charge limit was set to 60%. At the start, the 'time remaining' display was 3 hrs and 5 min which looked encouraging. I plugged the mobile connector into a Kilowatt meter to measure the power flowing into the truck. It read 1435W. I turned off all possible parasitic loads. The ambient air temperature was 64F, and the battery temperature was 18.75 - 22.25 deg C. The HV service display showed everything was working.

After the estimated 3 hrs and 5 min, the 'time remaining' still read 1 hr 10 min and the battery state of charge was only 58%. The Kilowatt meter recorded that 4.42 kWh of grid energy had been fed to the truck. The battery temperature had risen to 21.25-25.75 deg C.

I continued charging until the 60% charging limit was finally reached after 5 hrs and 15 min with 5 kWh of accumulated battery energy. The Kilowatt meter measured 7.57 kWh from the grid, so the charging efficiency was approximately 66%.

Frankly, I didn't expect such poor efficiency from Level 1 charging using the mobile connector, and it made me question the economic practicality of Level 1 charging as a routine practice. I'm also having doubts about using solar panels to augment the truck's battery charge to achieve more driving range. Better to use solar panels to power things that would otherwise drain energy from the truck's battery (refrigerator, A/C, electric appliances, etc.)

At higher charging power the situation is not so dire. I think my dual fuel generator will be a good fallback power source when extra driving range is needed.

That looks like they've got something wrong going on there, something they need to work on.

 

[scottf200]

The 2+ hrs extra, 66% efficiency, and the battery temperature increased from 18.75-22.25°C to 21.25-25.75°C, indicating some energy was lost as heat.

 

[igs]

I continued charging until the 60% charging limit was finally reached after 5 hrs and 15 min with 5 kWh of accumulated battery energy.

The display shows it's charging at 1kw so that's right.

The Kilowatt meter measured 7.57 kWh from the grid, so the charging efficiency was approximately 66%.

The computer alone uses 400w so that's also right.

 

[Jedi2155]

Off-road adventure in an all electric vehicle can be risky. Having a portable fossil fuel generator or solar generator can ease the anxiety of running out of battery miles from the nearest charging station. Understanding what constitutes a viable range extending power source is important, and the question of charging efficiency feeds into that understanding.

Today, I attempted to charge my Cybertruck from a 120V 15A receptacle in my garage using Gen 2 mobile connector (Level 1 charging). The battery was at 56% SOC and the charge limit was set to 60%. At the start, the 'time remaining' display was 3 hrs and 5 min which looked encouraging. I plugged the mobile connector into a Kilowatt meter to measure the power flowing into the truck. It read 1435W. I turned off all possible parasitic loads. The ambient air temperature was 64F, and the battery temperature was 18.75 - 22.25 deg C. The HV service display showed everything was working.

After the estimated 3 hrs and 5 min, the 'time remaining' still read 1 hr 10 min and the battery state of charge was only 58%. The Kilowatt meter recorded that 4.42 kWh of grid energy had been fed to the truck. The battery temperature had risen to 21.25-25.75 deg C.

I continued charging until the 60% charging limit was finally reached after 5 hrs and 15 min with 5 kWh of accumulated battery energy. The Kilowatt meter measured 7.57 kWh from the grid, so the charging efficiency was approximately 66%.

Frankly, I didn't expect such poor efficiency from Level 1 charging using the mobile connector, and it made me question the economic practicality of Level 1 charging as a routine practice. I'm also having doubts about using solar panels to augment the truck's battery charge to achieve more driving range. Better to use solar panels to power things that would otherwise drain energy from the truck's battery (refrigerator, A/C, electric appliances, etc.)

At higher charging power the situation is not so dire. I think my dual fuel generator will be a good fallback power source when extra driving range is needed.

66% efficiency is better than I thought, but fairly typical for L1 charging, this is common in ALL EV's since the EV's I use to drive 10+ years ago (Volt, Leaf, RAV4 etc.). Level 2 is needed to bring you efficiency to the 90%+ range.

 

[Cybergirl]

The 2+ hrs extra, 66% efficiency, and the battery temperature increased from 18.75-22.25°C to 21.25-25.75°C, indicating some energy was lost as heat.

Yes, that's true. At the end of the charge the battery temperature rose to 27 deg C. Add to that the AC to DC conversion inefficiency. Lowering the charging rate to 8A (1000W), I measured an efficiency of only 36%.

The display shows it's charging at 1kw so that's right.



The computer alone uses 400w so that's also right.

I doubt that when the truck is at rest the computers draw 400W. If that were true, in 12 hours, the battery would lose 12 x 0.4W = 4.8kWh. That's 3.9% battery loss.

 

[GuyV]

Yes, that's true. At the end of the charge the battery temperature rose to 27 deg C. Add to that the AC to DC conversion inefficiency. Lowering the charging rate to 8A (1000W), I measured an efficiency of only 36%.

I doubt that when the truck is at rest the computers draw 400W. If that were true, in 12 hours, the battery would lose 12 x 0.4W = 4.8kWh. That's 3.9% battery loss.

I question whether it was "lost as heat" or that it was intentionally heating the battery, unnecessarily at that rate of charge at those temperatures. We have already seen they have acknowledged L2 heating/charging algorithm problems at subfreezing temperatures.

Losses from transmission, conversion and heat generation from charging alone should not be that high. They ought to easily be able to operate all the computer systems at low power as well. Perhaps your monitoring kept them at higher activity.

 

[Crissa]

66% efficiency is better than I thought, but fairly typical for L1 charging, this is common in ALL EV's since the EV's I use to drive 10+ years ago (Volt, Leaf, RAV4 etc.). Level 2 is needed to bring you efficiency to the 90%+ range.

That's not quite true, re older Volt, Leaf, RAV4.

They had the older, 80% efficient, cheap chargers so they're always stuck there. It's not the overhead that makes it inefficient, it's just older (cheaper) methods of rectifying AC to the appropriate voltage for charging.

It's just like you can choose a more or less efficient power supply for a PC or your USB powered devices. And when I mean just like, it's basically the same electronics! Power supplies have to adjust for the load they're powering: Chargers, on the other hand, adjust the voltage for the charge level so the load remains as consistent as possible. It's the same thing, just a different control.

So for instance, the chargers for the Gen 2 Zero I have is always that 80% efficient - even if you have the Level 2 6kW one.

-Crissa

 

[Bobo_LaDouche]

Thank you for the facts; 5 hours for 5 kWh looks like 3 miles range per hour of charging. Not nice when carrying gas and listening to a generator. Yes, it will have to be a 240v gen-set.

Not sure there is a solar solution yet either. Maybe cross my fingers that Tesla makes a new dc solar gizmo product line for direct charging... holding my breath.

 

[mongo]

I question whether it was "lost as heat" or that it was intentionally heating the battery, unnecessarily at that rate of charge at those temperatures. We have already seen they have acknowledged L2 heating/charging algorithm problems at subfreezing temperatures.

Lost as heat. If you watch the thermal->coolant page it shows no active pack heating. It's just heat rejected from the computers and PCS.

 

[GuyV]

Lost as heat. If you watch the thermal->coolant page it shows no active pack heating. It's just heat rejected from the computers and PCS.

Something is wrong somewhere, losing half a kWh per hour just slow charging is crazy. The converter can't be that inefficient. Maybe the excess power use while monitoring is also making the heat management work harder as well. We know it burns a lot when sentry is on.

 

[cybercricket]

Something is wrong somewhere, losing half a kWh per hour just slow charging is crazy. The converter can't be that inefficient. Maybe the excess power use while monitoring is also making the heat management work harder as well. We know it burns a lot when sentry is on.

Conversion efficiency is lower when the voltage differential is higher. You get 120VAC input and you need to produce over 800VDC. Then the truck probably spends a bunch of juice running the computer, contactors, etc.

 

[ABILISK]

it made me question the economic practicality of Level 1 charging as a routine practice

… yeah…

Plugging into a 12A/110V socket is either a last resort or if you don’t need to drive for several days. It’s not designed for routine practice.

The ONLY thing it could be used for routinely is if you have a short drive to work and can plug in there while your car sits for 8-10 hours.

 

[mongo]

Something is wrong somewhere, losing half a kWh per hour just slow charging is crazy. The converter can't be that inefficient. Maybe the excess power use while monitoring is also making the heat management work harder as well. We know it burns a lot when sentry is on.

The pack heating is all due to inefficiencies elsewhere, once the pack is warm enough to charge at a rate that matches the charge connection. A 32A 240V charge calls for a warmer pack than a 12A 120V charge.

Conversion efficency is poor at lower power due to overhead of being on. The 500W is consumption by all the active electronics in the vehicle. Controllers, screen, charger, the cooling loop takes the heat from PCS and computers and transfers it to the pack.

Testing at 28F, I get 1% SOC every 90 minutes with 6A 240V, so net charge efficency of 57%. Losses of 620W. Took 45 minutes and 2% SOC to warm pack at start of charge.

Not sure on power draw if doing climate preconditioning from 1.44kW.

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